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#1
This is the remake of the old science thread!

This thread is for anybody who has an interest in science or for anybody who has a question. This thread is here to help with any revision for exams or homework help. The help given will only serve to explain your problem, and help you arrive at the answer you seek.

I dont want to see:

Flaming:

I dont care how ignorant someone is, I dont care how lacking someones scientific knowledge is, I will not tolerate flaming in this thread. This thread is here to help broaden everyones scientific knowledge.

Do not flame anyones scientific beliefs. Each to their own. Do not bring religion into any discussion (see below).

Religion:

Science and religion will never agree so dont post any religious/spiritual/other belief system here- Use the religion thread.

Politics:

Any politics goes in the political thread. If you want to discuss ethics of science then steer clear of politics or religion. This is hard when it concerns moral dilemas, but

again religion or politics thread if it is of that nature.

I want to see:

Healthy discussion of science! If you want to write an article, please do not plagerise it, if you do use sources- include links. Use your own words and be detailed in explanations (to the best of your knowledge) and make it understandable so that everyone can access the infomation you are putting across.

I want to see questions, debates and I want people to have fun!

Science sites:

http://www.chemicalforums.com/index.php
http://www.freewebs.com/science_questions/foreword.htm
http://www.tenthdimension.com/flash.php
www.popsci.com
http://www.newscientist.com/home.ns
http://www.innerbody.com/htm/body.html

------------------------

Credentials:

BSc Chemistry, MSc Drug Discovery.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Jan 15, 2012,
#2
Articles

Evolution By Freedoms_Stain

http://profile.ultimate-guitar.com/freedoms_stain/blog/31929/

YOU MUST READ THIS BLOG

Evolution by natural selection- Guitardude19

Evolution through natural selection.

This is the be all and end all so no arguing that evolution is a load of rubbish because if you have half a brain, you will at least understand this long post on this subject. Do not bring religion into it and do not dismiss it. This theory is very real and very true, do not bring any other theories into it because this is the very core of the theory. If you want to bring religion into it then you know what you have to do, get off the thread because religious discussion is not allowed.

EVOLUTION IS NOT A RELIGION IT IS A SCIENTIFIC THEORY!

Evolution is a process by which new species are formed from pre existing ones over a period of time. In order for evolution to occur, all organisms must produce large numbers of offspring, which if they survived would lead to a geometric increase in the size of the population. Despite the fact that organisms have a tendency to increase in numbers due to over production, the population actually remains constant. This is due to the fact that members of the species are constantly competing to survive. This struggle for existence means only a few will survive to breed. Any form of competition be it food territory or availability of mates will only be open to those who are best adapted to the prevailing conditions to survive. Those that are not adapted to suite the environment, or cannot compete adequately with the rest of the population die off. This means that those that go on to breed pass on their genes to the next generation thus the new offspring are better able to survive. However, in any sexually produced offspring of any species, there is always individual variation amongst members of that species. This means that generally, no two offspring are alike. (This excludes twins who are genotypically the same but maybe phenotypically different due to environmental factors). Amongst the offspring of any species within any population, there are some that are able to withstand the prevailing conditions of the environment. This means that some are better able to survive the struggle for existence, and those that are more likely to survive are the ones that are more likely to breed, and therefore produce offspring that are similar to themselves.

Advantageous characteristics are therefore passed onto the next generation which allows the next generation to be better adapted to their environment. Over time, the favourable characteristics pass through the population therefore spread through the gene pool. Development of variation over generations leads to the evolution of a new species.As we have seen, evolution is based on natural selection and those that are better able to survive prevailing conditions, go on to breed. However, in order to breed, these organisms need to be able to survive selection pressures. Selection pressures determine the spread of an allele amongst the gene pool. Where variation forms a normal distribution curve, there will be organisms that have ?average alleles? that allow it to survive prevailing conditions, and there will be organisms that have the extremes of these alleles that make them less able to survive the prevailing conditions. For example, in a population of polar bears, there is a mean fur length, short fur and long fur. If the selection pressure is temperature, the mean hair length and long hair length is favourable in cold temperatures, there for short fur is selected against, therefore short hair polar bears die out, therefore, the short hair allele is no longer in the population (not all short fur bears die because body fat composition may make up for what the fur lacks). This means the mean shifts to allow favourable medium and long fur alleles to prevail in the population and therefore, over time, longer haired species of polar bear develop. Where extreme characters (long fur in this case) are selected for, the mean allele frequency shifts in the population. This is due to a change in the environmental conditions. The colder it gets, the more the long hair allele is favoured (as shorter hair bears die off they cannot pass genes to next generation) therefore more bears are produced with longer fur. This is directional selection where one of the extremes is favoured as conditions change.

Another form of selection is stabilising selection, where the environment selects against the extremes of the population therefore favours the mean. This reduces the allelic variation amongst the population therefore reduces evolutionary change.
There are rare cases where the mean allele in a population is selected against. This is disruptive selection and favours the extremes within the population, therefore two distinct phenotypes are favoured (phenotype determined by genotype) therefore encourages evolutionary change. Although selection pressures can lead to variation amongst a population and over time, new species can develop, another more common method of evolution that is often over looked is speciation. Speciation is where a new species is formed from groups via isolation mechanisms. Within a population there are demes. A deme is a group of individuals within a species. A deme can breed with individuals from its own deme or other demes, thus keeping the gene pool wide and varied. However, if a deme is prevented from breeding with another deme, the gene pool becomes smaller, therefore separated and therefore isolated. When demes become isolated from other demes, speciation occurs via two mechanisms, allopatric and sympatric speciation.

Allopatric speciation is where a deme becomes geographically isolated by any physical barrier. These can include mountain ranges, rivers, oceans and any other form of physical barriers that prevent two demes from interbreeding.
Sympatric speciation is more complex and involves factors other than geographical factors. This is where reproductive isolation occurs by a number of factors. There may be mechanical isolation where the genitals are not compatible, therefore it is physically impossible for the male anatomy to enter the female anatomy. Even if intercourse can occur, the male gametes maybe prevented from meeting the female gametes as the male gametes may not survive female reproductive tract. Another factor maybe that the gametes do not fuse because they are not compatible. If gametes do fuse, hybrid initability may occur where chromosomal abnormalities may occur preventing the survival of the embryo. Polyploidy may cause hybrid sterilisation. (Polyploidy will be explained later). Also, another factor is behavioural isolation, where courtship rituals prevent reproduction as the rituals differ. A factor with plants is seasonal differences, where some plants release pollen before female parts of plant are developed, but develop in another season.

Another big factor in evolution is variation due to genetic mutations. This can be recombination during prophase one of meiosis. This is where chromatids are exchanged that lead to changes in the genotype. During metaphase one of meiosis there is random distribution of chromosomes, and during prophase one, there is crossing over of homologous chromosomes. These are not necessarily forms of mutations, but that are inbuilt methods of variation where genes are swapped between chromosomes to deliberately change the genotype. A mutation is a change in the structure or the amount of DNA. Any mutation that occurs in somatic cells are not passed on to the next generation. Only mutations that occur in gametes are passed on as these are the cells used in reproduction. A point mutation occurs at a specific locus on a chromosome. These are a change in a specific nucleotide base pair. There can be duplication where a portion of DNA is repeated. There can be insertion, where an extra nucleotide sequence is added in. There can be deletion, where a portion of DNA is removed. Inversion can occur where a portion of the DNA sequence is removed, but joins back on to the chromosome in its reversed position. Substitution can occur where a nucleotide is replaced by another. All of these lead to evolutionary change because they alter the phenotype. Any change in the genotype alters the phenotype so much so a new species is formed as any two organisms now differ.Another type of mutation that leads to evolutionary speciation is a change in the structure of the chromosomes. During meiosis (pronounced my oh sis) chromosomes form chiamesta. This is where chromosomes break off into chromatids and rejoin. This can lead to new genotypes by similar mechanisms to point mutations. Deletion can occur.

This is where a portion of the chromosome is lost, however, this involves a loss of genes and is often fatal. Inversion can occur where the chromatid breaks off and rejoins in its reversed position. The gene sequence is reversed, but the genotype stays the same. This could however, alter the phenotype. This indicates that the sequence of the genes is important, as a change in the gene sequence can alter phenotype. Also, translocation can occur. This is where a chromatid becomes deleted and rejoins on a different position on the chromosome, or joins a new chromosome. The final type of chromosome mutation that can occur is duplication, where a whole sequence of the chromatid is repeated, therefore resulting in a repetition of the gene sequence. This can lead to new species forming as the genotype is changed in some way that alters the phenotype. This can lead to reproductive isolation therefore, new species can form.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Jun 6, 2008,
#3
Whole sets of chromosomes can be changed or exchanged. Polyploidy is where an organism has an additional set of chromosomes. This can arise where gametes become diploid and are self fertilised. It can also occur where whole sets of chromosomes double after fertilisation. This can lead to sterile hybrids such as a donkey and horse cross. Hybrids are formed when two organisms of differing chromosomes are mated. This leads to allopolyploidy where the hybrid can have a diploid divide to a haploid chromosome number evenly. Non disjunction can occur where chromosomes fail to separate during anaphase in meiosis. This can be fatal because the gametes have one extra or one less chromosome therefore not all genetic information provided to make new organisms, or if there is too much information, the organism is disabled in someway. However, all of this may lead to new species forming as there is an altered genotype. If the genotype is changed, the phenotype is changed. This leads to an increase in the variation of the population, therefore any changes over time lead to an increase of allelic frequency in the gene pool. This combined with selection pressures favouring one set of alleles over another, coupled with forms of isolation mechanism can lead to speciation.


The Periodic Table- Guitardude19

Here we go with the periodic table:

The first number is the relative atomic mass.
The second number is the atomic number.

Period One

H (1,1) Hydrogen - Group 1
He (4,2) Helium - Group 0

Period Two

Li (7,3) Lithium - Group 1
Be (9,4) Beryllium - Group 2
B (11,5) Boron - Group 3
C (12,6) Carbon - Group 4
N (14,7) Nitrogen - Group 5
O (16,8) Oxygen - Group 6
F (19,9) Flou(censor)rine - Group 7
Ne (20,10) Neon - Group 0

Period Three

Na (23,11) Sodium - Group 1
Mg (24,12) Magnesium - Group 2
Al (27,13) Aluminium - Group 3
Si (28,14) Silicon - Group 4
P (31,15) Phosphorus - Group 5
S (32,16) Sulphur - Group 6
Cl (35.5,17) Chlorine - Group 7
Ar (40,18) Argon - Group 0

Period Four

K (39,19) Potassium - Group 1
Ca (40,20) Calcium - Group 2
Sc (45,21) Scandium - Transition
Ti (48,22) Titanium - Transistion
V (51,23) Vanadium - Transistion
Cr (52,24) Chromium - Transistion
Mn (55,25) Manganese - Transistion
Fe *Pause* (56,26) Iron - Transistion
Co *Pause* (59,27) Cobolt - Transistion
Ni (59,28) Nickle - Transistion
Cu (63,29) Copper - Transistion
Zn (65,30) Zinc - Transistion
Ga (70,31) Gallium - Group 3
Ge (73,32) Germanium - Group 4
As (75,33) Ar(censor)senic - Group 5
Se (79,34) Selenium - Group 6
Br (80,35) Bromine - Group 7
Kr (84,36) Krypton - Group 0

Period Five

Rb (86,37) Rubidium - Group 1
Sr (88,38) Strontium - Group 2
Y (89,39) Yttrium - Transistion
Zr (91,40) Zincronium - Transistion
Nb (93,41) Niobium - Transistion
Mo (96,42) Molybdenium - Transistion
Tc (99,43) Technetium - Transistion
Ru (101,44) Ruthenium - Transistion
Rh (103,45) Rhodium - Transistion
Pd (106,46) Palladium - Transistion
Ag (108,47) Silver - Transistion
Cd (112,48) Cadmium - Transistion
In (115,49) Indium - Group 3
Sn (119,50) Tin - Group 4
Sb (122,51) Antimony - Group 5
Te (128,52) Tellerium - Group 6
I (127,53) Iodine - Group 7
Xe (131,54) Xenon - Group 0

Period Six

Cs (133,55) Caesium - Group 1
Ba (137,56) Barium - group 2
La (139,57) Lanthinium - Lanthanide
Ce (140,58) Cerium - Lanthanide
Pr (141,59) Praseodymium - Lanthanide
Nd (144,60) Neodymium - Lanthanide
Pm (147,61) Promethium - Lanthanide
Sm (150,62) Samarium - Lanthanide
Eu (152,63) Europium - Lanthanide
Gd (157,64) Gadolinium - Lanthanide
Tb (159,65) Terium - Lanthanide
Dy *Pause* (163,66) Dysprosium - Lanthanide
Ho (165,67) Holmium - Lanthanide
Er (167,68) Erbium - Lanthanide
Tm (169,69) Thulium - Lanthanide
Yb (173,70) Ytterbium - Lanthanide
Lu (175,71) Lutetium - Lanthanide
Hf (179,72) Hafnium - Transistion
Ta (181,73) Tantalum - Transistion
W (184,74) Tungsten - Transistion
Re (186,75) Rhenium - Transistion
Os (190,76) Osmium - Transistion
Ir (192,77) Iridium - Transistion
Pt (195,78) Platinum - Transistion
Au (197,79) Gold - Transistion
Hg (201,80) Mercury - Transistion
Tl (204,81) Thalium - Group 3
Pb (207,82) Lead - Group 4
Bi (209,83) Bismuth - Group 5
Po (210,84) Polonium - Group 6
At (210,85) Astatine - Group 7
Rn (222,86) Radon - Group 0

Period Seven

Fr (223,87) Francium - Group 1
Ra *pause* (226,88) Radium - Group 2
Ac (227,89) Actinium - Actinide
Th (232,90) Thorium - Actinide
Pa (231,91) Protactinium - Actinide
U (238,92) Uranium - Actinide
Np (237,93) Neptunium - Actinde
Pu (244,94) Plutonium - Actinide
Am (243,95) Americium - Actinide
Cm (247,96) Curium - Actinde
Bk (247,97) Berkelium - Actinide
Cf (251,98) Californium - Actinide
Es (252,99) Einsteinium -Actinide
Fm (257,100) Fermium - Actinide
Md (258,101) Mendelevium - Actinide
No (259,102) N(Censor)obelium - Actinide
Lr (260,103) Lawerencium - Actinide
Rf (261,104) Rutherfordium - Transistion
Db (262,105) Dubrium - Transistion
Sg (263,106) Seaborgium - Transistion
Bh (262,107) Bohrium - Transistion
Hs (265,108) Hassium - Transistion
Mt (266,109) Meitnerium - Transistion
Ds (262,110) Darmstadtium - Transistion
Uuu (272,111) Ununumium - Transistion (Rg Roentgenium)
Uub (277,112) Ununbium - Transistion
Uut (-,113) Ununtrium - Group 3 (Undiscovered)
Uuq (289,114) Ununquadium - Group 4
Uup (-,115) Ununpentium - Group 5 (undiscovered)
Uuh (-,116 Ununhexium - Group 6 (undiscovered)
Uus *pause* (-,117) Ununseptium - Group 7 (undiscovered)
Uuo (-,118) Ununoctium - Group 0 (undiscovered)

Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Feb 26, 2009,
#4
Organic Chemistry Basics- Guitardude19

In this article I will post what organic chemistry is, how we name the molecules, how they react, and why they react . Have fun reading it. Its going to be very long and hopefully enjoyable.

Organic chemistry has far and wide reaching benefits to the world. Organic chemistry refers to hydrocarbons. Hydrocarbons are molecules that contain carbon and
hydrogen. These can be found in oil. Carbon atoms have the ability to bond to themselves infinitely because they have four electrons in their outer shell. This means that a hydrocarbon chain can have one carbon atom, or a million carbon atoms (and more). This unique ability for carbon to bond to itself infinitely means that there are over 10 million known hydrocarbon molecules.

Having so many molecules poses a problem. How do you name them? Well, the first thing you need to know is its chain length. Here is a list of the prefixes for a carbon

chain:

A single carbon atom is termed Meth-
Two carbon atoms are termed Eth-
Three carbon atoms are termed Prop-
Four carbon atoms are termed But-
Five carbon atoms are termed Pent-
Six carbon atoms are termed Hex-
Seven carbon atoms are termed Hept-
Eight carbon atoms are termed Oct-
Nine carbon atoms are termed Non-
Ten carbon atoms are termed Dec-

The suffix of a hydrocarbon is the functional group. A functional group is the region at which the reaction occurs. A hydrocarbon that has varying chain lengths but has the
same functional group belongs to a homologous series. A homologous series is just a way of classifying similar molecules because they all react the same way (but at
different rates because the long the chain the less likely it is to react due to stearic hindrance. Stearic hindrance is where a reaction does not proceed because the
molecules cannot come together because atoms on the molecule block them from coming into contact).

Here is a list of all the prefixes:

A hydrocarbon chain with no double bonds between the carbons is termed -ane. C-C.

A hydrocarbon chain with any amount of double bonds between any carbon atoms is termed -ene. C=C.
Incidentally it must be noted that if more than one double bond exists in a chain, the double bond cannot come directly after another double bond because there will be

electron repulsions that make the chain unstable. The bonds are unstable because the pi bond extends upwards and two extended bonds create large repulsions. C=C=C-C

cannot happen but C=C-C=C can happen.

A hydrocarbon with an oxygen double bonded to one carbon atom that is bonded to two other carbon atoms either side are termed -one. C-C(O)-C. These molecules are
known as ketones. These cannot occur at the end of the chain because there will be an extra bond left. A hydrocarbon chain with an oxygen at the end of the chain and a hydrogen on the end of the chain is termed - al. These are known as aldehydes. C(O)H These occur at the end of the chain because the oxygen is double bonded to the carbon atom.

A hydrocarbon chain with a hydroxy group is termed -ol. C-OH These are known as alcohols .

A hydrocarbon chain with a hydroxy group on the end of a chain with a double bonded oxygen at the end of a chain are termed -oic acid. COOH These can only be found at the end of a carbon chain because the oxygen is double bonded to the carbon. These molecules are known as carboxylic acids.

A hydrocarbon chain with a cyano group on them are termed nitriles CºN. These are found on the end of chains because the carbon nitrogen bond is triple bonded.

A hydrocarbon chain with an amino group C-NH2 are termed amines.

A hydrocarbon chain with an amino group and a double bonded oxygen, both at the end of a chain are called amides CONH2.
A hydrocarbon chain with any halogen atom bonded to it is termed -ide for example chloride bromide iodide and flouride. C-Cl C-Br C-I

A hydrocarbon chain with a double bonded oxygen at the end of a chain with a chloride ion bonded to them are termed acid chlorides COCl.

An alcohol and a carboxylic acid can react to form an ester (acid chlorides also react in the same way to form an ester. Amides react to form esters that are known as secondary amides. These will be dealt with later. Esters are COC(O)C.

Now we have the prefixes, we can name our molecules. If we have a three carbon chain with no double bonds and an OH group on the end of the chain we call this molecule Propanol. (Ethanol is the alcohol in all alcoholic drinks). However, that alcohol group can go anywhere on the chain. We name them by adding a number to the carbon it is bonded to. So if the OH group is bonded to the second carbon on our three carbon chain we call it proan-2-ol. The same is true with double bonds. If we have a double bond in a five carbon chain and it is between carbon two and three, we can either name it pent-2-ene or pent-3-ene. The usual way to do this is to take the lowest number, so we call this molecule pent-2-ene.

If we have more than one functional group on our molecule, we name it first by the functional group with the highest molecular mass and then list the other groups alphabetically with their numbers respective to the carbon atoms they are bonded to. If we have a six carbon chain with a carboxylic acid group at the end of the chain and a OH group on carbons 3 and 4, we call this 3,4 di hydroxy hexanoic acid. The di is added to show that there are two hydroxy groups.
If you have three of the same group, it is called tri, four is tetra. These are independent of the groups so they do not count as the alphabetical naming system, only the functional groups are named alphabetically. So you can have 1,2,3,4 tetra chloro 5,9 di hydroxy 6,7,8 tri iodo decane. (That is one funky molecule).

Now we come on to side chains. Side chains are named as numbered suffixes as follows:

A single carbon branched chain is called methyl
A two carbon branched chain is called ethyl
A three carbon chain is called proply
Basically you add -yl to the prefix to make it a suffix.
(-yl is also used to name esters which will be explained later on).

So if we have a seven carbon chain with a methyl group on the fourth carbon we call it 4 methyl hepatane.

Hydrocarbons undergo many types of reactions. Before I go on to those, I will explain why they react but in order for you to understand this I will explain electro negativity.

Electro negativity is a property that all atoms have that relates to its ?electron pulling power.? This refers to all chemical reactions because it helps to explain why things react. Basically, a metal has a low electro negativity because it wants to lose its electron to gain a full outer shell. A non metal wants to gain an electron to get a full outer shell. What determines this is the force of attraction of the nucleus to the electron on another atom. Small high charged anions have a high electro negativity because they are able to exert a greater force on a metals electron than a larger anion. This is because a small atom has less shells of electrons and can therefore exert a greater force. A large anion has more shells of electrons than a smaller one so it will therefore experience more shielding and therefore exert less of force on an electron on a metal. Also, in covalent compounds electro negative atoms distort the electron cloud around the less electro negative atom. This leads to polarisation of the bond which makes the highly electronegative atom partially negative and the less electo negative atom partially positive. However, we assign these atoms with a number. Flourine is very electro negative and is given a EN value of 4. Oxygen is 3.5 and nitrogen is 3 and chlorine is 3 carbon is 2.5 and hydrogen is 2.1. The higher the EN value the stronger its pull for electrons. This relates to organic chemistry because the EN values explain how distorted a molecule is by the atoms that are bonded to them. Alkanes are composed of carbon and hydrogen (saturated hydrocarbons) only and will not react with anything because there is very little polarisation.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Mar 20, 2007,
#5
The other major factor in reactions is charge distribution on a molecule which can be largely due to EN values of the respective atoms. However, alkenes (unsaturated

hydrocarbons) can react with many ions because the double carbon bond is partially negative. Partial charges attract ions of the opposite charge so now we need to classify

our reactions. The reactions are classified by the type of species that are going to react with our molecule. There are three types, a nucleophile, an electrophile and a free

radical.

A nucleophile is a species with lone pairs of electrons that attack positive centres on a hydrocarbon chain.

An electrophile is a species with a electron deficiency and attacks centres of negative charge.

A free radical is a species with a single unbounded electron that attack centres of positive charge.

The type of reactions that molecules undergo are substitution, addition, condensation (can be called dehydration), hydrolysis and combustion.

A nucleophillic substitution reaction is where a nucleophile replaces a group on a hydrocarbon chain.
A nucleophillic addition reaction is where a nucleophile is added to a hydrocarbon chain.
An electrophillic addition reaction is where an electrophile is added to a hydrocarbon chain.
A condensation reaction is where water is removed from a molecule. (Esterfication reactions are special case and I will explain them later in the article).
A hydrolysis reaction is where water is added to a molecule.
Combustion is where oxygen reacts with a molecule to create oxygen based compounds (water and carbon dioxide).
Free radical substitution is where a free radical substitutes itself onto a molecule.

Now lets look at specific reactions that under each of the above.

Nucleophilic susbstitution reaction:

Ethanol + Hydrogen Bromide à Bromoethane + Water.

In this reaction, the hydroxy group polarises the carbon to which it bonds. The hydrogen bromide has charges induced on it because the partial positive charge on the

carbon pulls the electron cloud on the bromine. This causes the bromine to be pulled into the carbon. The electrons on the bromine repel the electrons on the hydroxy group

causing the bond to break. The hydrogen on the hydrogen bromide is repelled off the molecule and bonds to the hydroxide ion and forms water.

Nucleophilic addition reaction:

Propanal + hydrogen cyanideà 2-hydroxy butanitrile

The oxygen on the carbon causes the carbon to become partial positive and the cyanide ion bonds to the carbon and breaks one of the bonds on the oxygen, giving a

negative charge to it. The hydrogen from the hydrogen cyanide is attracted to the negatively charged oxygen creating a hydroxy group.

Electrophilic addition reaction:

Propene + Bromine à 1,2 di bromo propane.

These occur on alkenes where the double bond is partially positive. The partial negative charge on the bond can induce partial positive charges on any species.

Condensation reaction:

Basically anything where water is formed when two molecules come together. A special type of condensation reaction is estification. I will cover this later because

estification reactions don?t always produce water.

1 amino butanoic acid + 1 amino butanoic acid à Butanoyl butanamide + water.

Butanoyl butanamide is a secondary amide because the amino group bonds two carbon chains together.

The above is actually an estification reaction because it can continue to react with itself for ever and ever if there were enough of the molecules, which is a form of

polymerisation.

Another estification reaction can occur between alcohols and carboxylic acids.

Ethanol + ethanoic acid à Ethyl ethanoate + water

This reaction is reversible. The reverse of this is the hydrolysis reaction.

Another estification reaction occurs between acid chlorides and alcohols. This yields hydrochloric acid instead of water.

Ethanoyl chloride + ethanol à ethyl ethanoate + hydrochloric acid.

This reaction is not reversible because the hydrochloric acid is a gas and leaves the container (read my article on equilibria on the first few pages to get to know reversible

reactions).

Naming esters isn?t so easy. An oxygen bonds two carbon chains together and one of the chains also has a double bonded oxygen that originates from the acid. So the

part of the chain that was originally the alcohol is termed -yl and the part of the chain that was the acid is termed -oate. So two carbons on each chain gives ethyl ethanoate.

Free radical substitution reaction:

This is a very bad way of making polymers because they make low density plastics. This means that the free radical attacks anywhere on the carbon chain to add another

chain to it making it pack badly in a crystal hence low density plastics are weak.

However the reaction goes thus.

Butane + Chlorine + ultraviolet light à 1 chloro butane up 1 tri chloro 2, 3 di chloro 4 tri chloro butane + hydrochloric acid.

Usually when this reaction proceeds, the free radical creates other free radical hydrocarbon chains that attack any partial charge because the free electron has a full charge

instead of its partial charge.

Combustion reactions:

Any hydrocarbon undergoes combustion to create carbon dioxide and water. Any amines or amides or anything with a halogen will create pure nitrogen or pure halogen

atoms.

Now to some general reactions where we use other compounds to make useful compounds.

If we want to make an alcohol we can take a hydrocarbon with halogen atom on it and react it with sodium hydroxide and warm it.

So if we have 1 bromo pentane and react it with sodium hydroxide, we make a primary alcohol called pentanol. A primary alcohol is when the hydroxy group is bonded to a

carbon that is bonded to one other carbon.

Now if the halogen atom is on the second carbon, we have 2 bromo pentane, when we react that with sodium hyrdroxide, we get pentan-2-ol and we get a secondary

alcohol. A secondary alcohol is when the hydroxy group id bonded to a carbon that is bonded to two other carbons.

If we had an branched chain of our five carbon chain where the hydroxy group was bonded to a carbon which is bonded to three other carbons, we would have a tertiary

alcohol.

So 2 methyl butan-2-ol is made from the reaction of sodium hydroxide and 2 bromo 2 methyl butane.

Now if we oxidise our alcohols, we can get ketones and aldehydes depending on what apparatus we use to oxidise it with. The compound used to oxidise alcohols is

acidified potassium dichromate.

A primary alcohol in distillation apparatus creates an aldehydes.
A primary alcohol in reflux apparatus creates a carboxylic acid. If we react the carboxylic phosphorus pentachloride we would create an acid chloride and hydrochloric acid

which would be identified as steamy white acidic fumes.
A secondary alcohol in either reflux or distillation apparatus will create a ketone. A ketone is an oxygen that is bonded to a carbon that is bonded to two other carbons so

cannot be oxidised further because all four bonds are used.
A tertiary alcohol cannot be oxidised because all four bonds around the carbon are used.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Apr 19, 2007,
#6
There as an orange to green colour change when alcohols are oxidised. This is because the chromate ion is reduced and therefore its electron transition creates a green colour. We can reduce carboxylic acids and aldehydes back to alcohols by use of lithium aluminium hydride in dry ether.

If we react ketones and aldehydes with cyanide ions we can create alcohols again. A reaction with an aldehydes creates a primary alcohol and a reaction with a ketone creates a secondary alcohol.

Now that we have seen basic alcohol reactions, lets look at basic nitrogen containing reactions.

If we react bromo ethane with hydrogen cyanide, we get propanitrile and hydrogen bromide. We can react the propanitrile with lithium aluminium hydride to create an amine. We can react our amine with hydrochloric acid to make it more soluble in water (the NH2 group becomes an ion of NH3 plus). Another thing we can do with nitriles is that if we react then with hydrochloric acid and a bit of water, we can turn them into carboxylic acids.

If we have an acid chloride, and react it with ammonia, we from an amide. These amides can undergo estification and polymerisation reactions to make secondary amides. With the use of tetra phosphorous deca oxide we can dehydrate them into nitriles.

Amides can undergo Hoffman degradation reactions, where they are degraded into amines. To do this, you need some bromine and sodium hydroxide. You make a methyl amine and sodium carbonate with some sodium bromide and water.

Next we will cover basic reactions of aldehydes and ketones. They both react with hydrogen cyanide to make alcohols. If we had an aldehyde, it would make a primary alcohol. If it was a ketone that the cyanide reacted with, it would make a secondary alcohol. To test whether we have an aldehyde or a ketone, we would use 2,4 di nitro phenyl hydrazine in phosphoric acid and ethanol.. It would give a yellow precipitate if either an aldehyde or ketone was present. To further distinguish between them, we could react the solution with alkaline aminical silver nitrate solution. If the aldehyde is present, then a silver mirror is formed in the solution. If not, you have a ketone. Another method to test for an aldehyde is Fehlings solution. This oxidises the aldehyde and reduces the copper solution to copper oxide. So you get a blue to brick red colour change. The last test is the iodoform test. You add iodine and sodium hydroxide to your solution. It gives a yellow precipitate and an antiseptic smell. The problem with this test is that it also works on methyl alcohols. So if you have an alcohol on the end of a chain, it will test positive for that too. So not a good way to distinguish them.

The very last part of organic chemistry that I will delve into is Grignard formation. We have seen that when a more electro negative atom reacts with a carbon, it distorts the electron cloud around the species and causes the carbon atom to become partially positive. We can make a carbon atom more negative if we react them with metals. However, only a certain type of metal and a certain type of hydrocarbon will work. If we have a halo alkane, and we react it with magnesium in dry ether, we get an unstable intermediate known as a Grignard reagent. This is reagent is magnesium bromide bonded to the carbon chain (only if the halo alkane was a bromo alkane). The great thing about this is that it can react with aldehydes to form primary alcohols and ketones to form secondary alcohols. Not only that, we can make chains very long with these since we can cause a deca alkane with a Grignard on it to react with another molecule of the same length to make a twenty carbon long chain. Also, with the right reagents, we can make very very long ester polymers that can withstand high temperatures, have a lot of strength and are ductile. Just to add, to make a Grignard, the ether had to be dry because water creates an alkene and magnesium iodo hydroxide.

Now we have reached the end of the article. If you have any questions, feel free to ask. I hope you have enjoyed reading it.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Mar 20, 2007,
#7
Entropy-By Hemant

Entropy suggests that everything (ie a closed system thats NOT in equilibrium) will tend toward a more disordered state. It will be the most disordered at equilibrium

It comes from the second law of thermodynamics if my memory serves me correctly, and basically means that spontaneous changes will happen within a system so that whatever is inside will tend towards entropy.

However, two different entropies need to be considered. If for eg you have an exothermic reaction, where energy is given out by the reaction, then two different entropy changes take place: that of the system (ie reaction) and that of the surroundings.

In order to calculate the entropy of the surroundings the formula used is Entropy = -dH/ T

This is the negative standard enthalpy change of the reaction (Jmol-1 - so remember to convert it from KJmol-1 to Jmol-1 by multiplying by 1000) divided by the temperature at which the reaction is happening.

As you may be able to see, the entropy change of a system is positive ( the neg-neg) when you have an exothermic reaction. More energy is being given out, which means the surroundings are becoming more disordered.

Therefore to calculate the entropy change of the system you need to know the entropy of the individual chemicals - which can be found in a data book.

Using this and the surrounding entropy change, you can calculate the overall change in entropy using Total Entropy Change = Change of Entropy of system + Change of surroundings

This overall value will tell you how the entropy has changed. If you have a positive entropy change then it is feasible that the reaction will proceed spontaneously - KEEP in mind that this does not suggest anything for the rate... just how spontaneous a reaction itis.

Entropy tends to increase when you have change of states from solids > liquids > gases - gas being most disordered.

This increase also happens when for eg 2 mols of reactant form 4 mols of product. More mols have been produced hence more disorder.

Complexity of molecules also contribute to this entropy change... If your product is more complex, there is more disorder.

Hope that helped, and that you understood it.

If I've made any mistakes please correct them, as it has been about a year since I did entropy properly.

Light in Relation to Time Travel-By Hemant

Light travels, denoting a period of time, therefore travelling faster than that will allow you to catch up with light from the past.

------------------------------>L-------------->L-1
===============>L==> L-1

L is where light is at present and L-1 is where light from the past is (1 being an arbitrary unit)
The = is a faster than light speed and -- is simply light speed

Hence you shall obviously reach light waves from the past quicker than if you were travelling at light speed as you are travelling faster than them.

However, you still wouldn't be able to do anything - You can't interact with light - they're just waves from the past.

Let me try and explain it a bit better.

We couldn't travel at the speed of light or faster because we have mass.

According to an equation from Einsteins theory of special relaticvity:

p = (mv)
_______

root(1-(v/c))^2

Essentially, as v ( the speed you travel at ) reaches 3 x 10^8 (C), the root(1-(v/c))^2 becomes closer and closer to zero - because the root of 1-1 = 0

Therefore you divide the momentum (p = mv) by something tending to zero, making the momentum approaching infinity.

now p = mv
E = 1/2mv^2

Combine these to get E = 1/2 pv

Therefore as momentum reaches inifitiy - the energy required to reach this momentum would be unavailable, and so an accelleration to reach such a momentum could not be reached.

Now take into consideration E = mc^2:
if the energy required to reach such a momentum is inifinity, and the speed of light is a constant - we can only change the mass of the object. The mass increases to the point where mc^2 is infinity.

Therefore, practically, to travel at the speed of light or more is impossible, and hence time travel is impossible. Theoretically it may well be possible.

This is according to Einsteins theory of relativity.

If I have anything wrong, please correct, as I've just woken up, and don't possess a degree is theoretical physics to be able to do justice to such a topic.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
Last edited by Guitardude19 at Mar 20, 2007,
#8
The Nature and Types of Bonding- A Basic Overview.

Every chemical, every molecule, compound, and element, whatever you want to call them, have some form of chemical bonding between their constituent atoms. Also, every molecule or compound has some form of bonding that occurs between the molecules themselves. Bonding that occurs within a molecule, that is the bond between each constituent nuclei, is know as an intra-chemical bond, and a bond that occurs between two molecules (be it of the same compound or other compounds/molecules) is known as an intermolecular bond.

Intra-molecular Bonds

Here is a list of intra-molecular bonds:

Ionic
Covalent

Inter molecular bonds

Here is a list of inter molecular bonds:

Hydrogen bond
Dipole moment
Induced dipole moment
Dative covalent

The Nature of The Atom

Before bonding can be considered, the nature of the atom must be considered. Bonding occurs in many different ways. In the case of an ionic bond, there is a complete transfer of electrons and in a covalent bond, there is a sharing of electrons. However, one must consider how the electrons are arranged in space.

The first model of the atom was the plum pudding model which stated that the atom consisted of a positive sphere with negative charges embedded within the positive sphere. In 1929, Rutherford performed the gold leaf experiment. This experiment deduced that the atom had a central positive nucleus and a cloud of negative charge with electrons orbiting it. This deduction was made due to the fact that some alpha particles that were bombarding the gold atoms were back scattered at 180 degrees. However the problem with this model is that it assumed the electrons orbited the nucleus in a spherical orbit. Under classical physics, a circulating charge will give off radiation and collapse back into the nucleus. If that happens the atom is annihilated. So, Bohr came up with a model that stated that the electrons were quantised, i.e., they had discrete energies within an allocated orbital and that the number of electrons in that orbital were fixed. This model was close and could explain another phenomenon that puzzled scientist, the phenomenon of the hydrogen spectra having specific frequencies of absorption and not being a continuum as would have been expected with the Rutherford model. The Bohr Model still assumed that elements had 2 electrons in the inner most shell, and 8 in the other shells and could not explain the existence of sub shells and the electron configurations of the transition, lanthanides and actinides. This is where the model of the atom changed. Schrödinger came up with a very complicated formula that is the accepted model of the atom, but only the hydrogen atom. The Schrödinger equation takes the wave function of the electron wave (it assumes the electron has wave and particle like properties, something I wont delve into here) in its angular and radial probabilities. This is due to the Heisenberg uncertainty principle which states that it is impossible to know the exact location of an electron at any given moment in time. The Schrödinger equation can be solved to give the n l ml and ms quantum numbers. The n quantum number is the principle quantum number and has any positive integer value between one and infinity. The n number defines the principle orbital energy level. The l number is the quantum number that defines the type of atomic sub-shells, s p d or f shells and has any integer value between 0 and (n-1). The l number describes the symmetry of each orbital and therefore the region of space the electron is most likely to occupy, as well as the angular momentum of the electron. The ml value is the magnetic quantum number and relates to the directionality of the orbital and therefore consequently shows the number of the sub-shells present and has any integer value of +l, 0 and -l. The ms value is the spin of the electron. It shows that any electron pairs cannot occupy the same spin state in the same orbital. Therefore the ms values are either +1/2 or -1/2.
The solution Schrödinger equation therefore gives the following:

For principle quantum number n=1 the allowed values of l are 0 and the allowed values of ml are 0. Therefore the first shell is spherically symmetric about the nucleus and is called the s sub-shell.



For principle quantum number n = 2 the allowed values of l are 0 and 1 and the allowed values of ml are -1 0 +1. This is shows that for n=2 there is a p orbital and they are directed in the px py and pz directions, therefore three of them. Also the p orbitals are dumbbell shaped.



For principle quantum number n=3 the allowed values of l are 0 1 and 2 and the allowed values of ml are -2 -1 0 +1 +2. This shows that there are d orbitals and there are 5 of them.



For principle quantum number n=4 the allowed values of l are 0 1 2 and 3 and the allowed values of ml are -3 -2 -1 0 +1 +2 +3. This shows the f shell and there are 7 of them.



The following can be summed up as:

For l = 0 the resulting orbital is an s orbital, l=1 is a p orbital l=2 is a d orbital and l=3 is an f orbital.

Each orbital can hold 2 electrons in them, so for an s orbital there is only 2 electrons and according to the Pauli exclusion principle, no two electrons can occupy the same spin state so the electrons are of opposite spin. A p orbital can hold 2 electrons per orbital and therefore can hold 6 electrons in total. A d orbital can hold 10 electrons and an f orbital can hold 14.
This therefore can explain the observed sub-shells for every orbital. So for n=1 you have only an s orbital with a total of 2 electrons, for n=2 you have an s and p orbital with a total of 8 electrons, for n=3 you have an s p and d orbital with a total of 18 electrons and for n=4 you have s p d and f orbital with 32 electrons which is in line with the observations done through ionisation energy.

It must be noted that all the orbitals are degenerate, that is all the electrons are at the same energy, therefore quantised. This fits in with the Bohr model and the Rutherford model as it assumes the nucleus is the centre of the atom.

The next paragraph is important in understand how bonding works. An s orbital has the same phase throughout, that is there is no change in the wave function of that orbital. There is a change of phase in the p d and f orbitals but this is not the concern of this article, however it is important to know this for how bonding works.

The Covalent Bond

The covalent bond is a sharing of electrons. It occurs between two nuclei where the probability of finding an electron is between the two nuclei. How a covalent bond works is dependant on molecular orbital theory. Molecular orbital theory states that for a covalent bond to occur an overlap of orbitals must occur. For this to work, the atomic orbitals are required that are symmetrical and have similar energies. If the orbitals are in phase, then a bonding orbital is formed. If the phases of the orbitals are different, then the molecular orbital formed is out of phase and has a nodal plane between them. Shown below are molecular orbital diagrams of s and p orbitals.





As you can see from the diagrams, where there is no nodal plane between the nuclei there is a bond, which is localised and where electrons are most likely to be found. Where there is a nodal plane, there is no electron density around between the electrons and is unfavourable for electron occupation as it is higher in energy. A covalent bond can therefore be thought of as a region in space where there is a high probability of finding an electron. Molecular orbital theory is a step up from valence bond hybridisation theory which states that any orbital with similar energy can overlap and form a hybrid between an s and p or s p and d. In carbon atoms the sp hybrid is seen due to the nature of carbon bonding where it is a tetrahedral shape that can go to trigonal planar under certain conditions. However molecular orbital theory shows this phenomena as not a change in orbital dimension, as the overlap occurs between the relevant orbitals and they can reform the p orbitals instead of hybridising to give the trigonal shape. The valence bond theory of hybridisation is not really used as it has many flaws in it that molecular orbital theory predicts.

Polarisation of The Covalent Bond

As seen above molecular orbital theory predicts the special arrangements of electrons around a covalent bond. This model is built around two nuclei that are of equal charge density and of equal electronegativity. Electronegativity is the ability of an atom to pull electrons close to its self. If two atoms are bonded via the covalent route, and one is more electronegative than the other, the bond becomes polarised. The more electronegative atom will have a partial negative charge and the less electronegative atom has a slight positive charge. This is important in explaining inter molecular bonds later. Also this means that the molecular orbital diagrams will have a shift in electron density around the more electronegative atom.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#9
The Ionic Bond

An ionic bond is formed when there is a complete transfer of electrons between a non metal and a metal. The metal loses its electron to form a cationic species and the non metal gains that electron to form an anionic species. The cationic species therefore as a full positive charge and the anionic species has a full negative charge. These opposite charges attract and form an electrostatic bond known as the ionic bond.

The above statement is a general overview of how an ionic bond works. However, that only works in a purely ionic system where there is no polarisation due to differences in charge density. Ionic bonds can be polarised to give a compound that is more covalent in nature. The charge density of a species is determined by the ionic radius of the atom and the charge on the atom. Under the definition above, LiBr would be assumed to be a purely ionic compound but it is far from it. Li+ has a small atomic radius and a charge density of +1 and therefore for its size has a very high charge density. Br- has a large atomic radius and a charge of 1- but due to its size, the charge density is significantly lower than that of the Li+ which has the same charge but a smaller radius. This means that in a bonding situation, the LiBr compound is more covalent in nature due to the fact that the small Li+ cation is able to distort the electron cloud around the Br- resulting in a polar bond. The same is true of non metals with a high charge density. If F- bonded to Pb the electron cloud around the metal would be distorted resulting in a more covalent compound.

The Dative Covalent Bond

The dative covalent bond occurs between two compounds where on is deficient in electrons and one has a lone pair. The dative covalent bond will form when the electron rich species donates its lone pair of electrons to the species deficient in electrons. Such molecules are NH3 and BH3 where the NH3 has a lone pair and donates it to the BH3.

Induced Dipole Moment

The induced dipole moment is also known as a van der waals bond. In all compounds, the electrons are mobile. They orbit around the central nucleus but can momentarily form a dipole where one atom has a slight positive charge on one side and a slight negative charge on the other. This is very fleeting but it can induce the effect on neighbouring atoms, and then across the whole molecule and indeed between all the molecules in the compound. This occurs in monatomic gases such as the noble gases and explains why they have such low melting and boiling points. The more electrons a species has the strong the effect as the overall slight charges increase.

The Dipole Moment

The dipole moment occurs in molecules where the one atom is more electronegative than another and therefore the more electronegative atom has a stronger pull for electrons and results in an overall slight positive and negative charge on the molecule. (see above where electronegativity was explained). The dipole moment can induce dipoles on other molecules as well however, in a compound such as propanone, the carbon has a slight positive charge and the oxygen a slight negative charge and the oxygen will bond with a dipole moment to a carbon on another propanone molecule.

The Hydrogen Bond

The hydrogen bond is a special case dipole moment as the bond involves a hydrogen being bonded to an element of high electronegativity, such as oxygen, nitrogen and fluorine. Water is hydrogen bonded where the oxygen atom has a lone pair of electrons and a partial negative charge and can bond to a hydrogen on another water molecule which has a partial positive charge.

I hope that this article was informative and if you have any further questions please post them. Like I said this is a basic overview of bonding, if you have specific questions or PM me and I will try to get back to you as soon as possible.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#10
The thread is now complete, feel free to post now.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#11
To somewhat get the ball rolling... Anyone else excited for that discovery channel special "Planet Earth"? I'm not sure what it's exactly about besides earth itself.
BRIGHT LIGHTS PUT ME IN A TRANCE.
but it aint house music that makes me want to dance.
#12
does a science double award GCSE count as two gcses
Yeah, now you're gonna die wearing that stupid little hat. How does it feel?

Help me to live.


I make custom guitar wiring harnesses and I'm pretty damn good at it!
#13
Quote by flyingmarlin
does a science double award GCSE count as two gcses


Um, its been a long time since I done GCSE but I assume it counts as two because I done triple science and it counted as three seperate GCSE's. Check with your school on that one.

Quote by Joe-Fish
To somewhat get the ball rolling... Anyone else excited for that discovery channel special "Planet Earth"? I'm not sure what it's exactly about besides earth itself.


If I had the Discovery Channel I would watch it.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#14
Quote by Guitardude19
If I had the Discovery Channel I would watch it.


I thought that you of all people would have it

Even though it's gone bad lately =/

Nice articles you posted, guitardude!
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#15
In order for me to recieve emails for replies I need to post...

Also to confirm my position of maths zealot; a little joke (or truth?):

The biologist wants to be a chemist.
The chemist wants to be a physicist.
The physicist wants to be God.
God wants to be a mathematician.




Finally for all the physics-y (or geeky) people: what are peoples views on Laurent Nottale and scale relativity? Personally I think it's a promising area of research, as is any quantum gravity principle that builds directly from general relativity (as opposed to spawning from quantum theory) but it is a shame that not many universities have the guts to fund anybody to look into it. String theory research funding should have been severly reduced 5 years ago, we are almost certainly not going to gain any useful information from it until we better understand the concept of QG.

I only mention this because I was day dreaming about 1/2 a year ago and had an idea that space itself could be fractal in nature, the consequences of this should be self evident (the scale at which you look at anything wouldn't matter, physics would be universal) and would almost certainly be the perfect GUT. And as NS did an article on this a week or two back, it's the perfect time to talk about it.


For sale: Early 1985 Ibanez AH10 (Allan Holdsworth signature model) PM for details
#16
To Kensai:

Nah, never had sky and I am univeristy now and we arent allowed to have sky lol.

To Powerfreak:

Long time no see dude. Interesting topic you brought up there, unfortunately I havent read NS in a while. Im gonna have to look into that.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#17
Quote by Guitardude19
Long time no see dude. Interesting topic you brought up there, unfortunately I havent read NS in a while. Im gonna have to look into that.

The NS article wasn't that great tbh. The best resource is straight from the horses mouth:

http://luth2.obspm.fr/~luthier/nottale/ukrechel.htm


Unless of course you want to read the updated cutting edge stuff which is EXTREMELY complicated and impossible to understand without cyborg level intelligence.


For sale: Early 1985 Ibanez AH10 (Allan Holdsworth signature model) PM for details
#18
planet earth is a wildlife documentary by the bbc and narrated by david attenborough if its the same planet earth that was shown in uk and ireland

its got amazing images of some places which are hardly ever shown on documentaries.
#19
Quote by Joe-Fish
To somewhat get the ball rolling... Anyone else excited for that discovery channel special "Planet Earth"? I'm not sure what it's exactly about besides earth itself.

Whens it on?
Beauty Supreme

Yeah you were right about me
#20
Quote by Guitarist132
Whens it on?


March 25th I think.

Discovery channel has gone to hell though. Half the shows are like biker build off and stuff.
BRIGHT LIGHTS PUT ME IN A TRANCE.
but it aint house music that makes me want to dance.
#22
OK, here's a vaguely sciency question that I've been thinking about for ages:

We've all been told god knows how many times that leaving your mobile phone charger plugged in wastes loads of energy - but how? Where does the electricity actually go, if the phone isnt there?
#23
Quote by mynamewontfit
OK, here's a vaguely sciency question that I've been thinking about for ages:

We've all been told god knows how many times that leaving your mobile phone charger plugged in wastes loads of energy - but how? Where does the electricity actually go, if the phone isnt there?


The charger takes in electricity from the wall and steps down the voltage. This takes energy. The energy leaves as a small amount of heat. Hell I just felt mine now and its warmer than expected. This is due to energy leaking in the form of heat as the voltage is stepped down. Even if the phone is not there, there is a voltage running through the initial part of the charger which is how the electrical energy is converted to heat. [Citation needed]
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#24
I tell you what else is interesting, now that we're talking about mobile phones:

I read in New Scientist that scientists are working on a small induction loop type of thing that can be fitted in tandem with your phone battery, so that when you make a call the microwaves actually charge your phone up. Obviously you'd still have to charge your phone, but it could be a lot less often.

I'll try to dig out the article so I can be more specific
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#25
Heh, I remeber that article. It was posted in the old thread now that you mention it.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#26
Quote by flyingmarlin
does a science double award GCSE count as two gcses


I think so, yeah.

Nice work, Guitardude19!


Quote by power freak
In order for me to recieve emails for replies I need to post...

Also to confirm my position of maths zealot; a little joke (or truth?):

The biologist wants to be a chemist.
The chemist wants to be a physicist.
The physicist wants to be God.
God wants to be a mathematician.




Finally for all the physics-y (or geeky) people: what are peoples views on Laurent Nottale and scale relativity? Personally I think it's a promising area of research, as is any quantum gravity principle that builds directly from general relativity (as opposed to spawning from quantum theory) but it is a shame that not many universities have the guts to fund anybody to look into it. String theory research funding should have been severly reduced 5 years ago, we are almost certainly not going to gain any useful information from it until we better understand the concept of QG.

I only mention this because I was day dreaming about 1/2 a year ago and had an idea that space itself could be fractal in nature, the consequences of this should be self evident (the scale at which you look at anything wouldn't matter, physics would be universal) and would almost certainly be the perfect GUT. And as NS did an article on this a week or two back, it's the perfect time to talk about it.






no idea about the second bit, I haven't read NS for ages, and my physics is a bit dodgy.
I'm an idiot and I accidentally clicked the "Remove all subscriptions" button. If it seems like I'm ignoring you, I'm not, I'm just no longer subscribed to the thread. If you quote me or do the @user thing at me, hopefully it'll notify me through my notifications and I'll get back to you.
Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
#27
Quote by Yakult
I tell you what else is interesting, now that we're talking about mobile phones:

I read in New Scientist that scientists are working on a small induction loop type of thing that can be fitted in tandem with your phone battery, so that when you make a call the microwaves actually charge your phone up. Obviously you'd still have to charge your phone, but it could be a lot less often.

I'll try to dig out the article so I can be more specific

That sounds cool, I've often thought it would be a good idea to do that sort of stuff with recycling energy.
Quote by Liberation
Every time I see your avatar I want to slit your neck with a butterknife. Goddamn Pingu.
#28
Quote by Yakult
...I read in New Scientist that scientists are working on a small induction loop type of thing that can be fitted in tandem with your phone battery, so that when you make a call the microwaves actually charge your phone up....


"perpetual motion" ideas always look good on the surface.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#29
Well, it wouldn't be perpetual motion. It's not claiming 100% efficiency, but it retrieves a small amount back. Kinda like heat exchangers in some engines.
#30
Quote by SomeoneYouKnew
"perpetual motion" ideas always look good on the surface.


No-one's claiming it's perpetual energy, just that it would obviously increase battery life
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#31
Quote by Yakult
No-one's claiming it's perpetual energy, just that it would obviously increase battery life



OMG, liek, shut the hell up you druNK!
On vacation from modding = don't pm me with your pish
#32
I don't know whether I'll get much of an answer at this time (being as late as it is), though hope springs eternal. The question is this: If a solvent (in this instance ethanol) is used to bring together two chemicals which normally wouldn't mix (water and an halogenoalkane), what name is given to such a solvent?

I'm just writing why I would use ethanol in the nucleophilic substitution of an halogenoalkane (1-iodobutane, 1-bromobutane and 1-chlorobutane). I know why, and I'd get the marks for explaining why, but my chemistry teacher used a term a few weeks ago which describes the role ethanol is playing here. It's not something silly like a bisolvent is it?
#34
Quote by meh!
OMG, liek, shut the hell up you druNK!


DAaMmnn it! All this whsky isss gone to my head! Of COURSE this is pepetual energy! Huzzah! No more power plants and CO2 emissions!
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#35
Quote by Robbie n strat
I don't know whether I'll get much of an answer at this time (being as late as it is), though hope springs eternal. The question is this: If a solvent (in this instance ethanol) is used to bring together two chemicals which normally wouldn't mix (water and an halogenoalkane), what name is given to such a solvent?

I'm just writing why I would use ethanol in the nucleophilic substitution of an halogenoalkane (1-iodobutane, 1-bromobutane and 1-chlorobutane). I know why, and I'd get the marks for explaining why, but my chemistry teacher used a term a few weeks ago which describes the role ethanol is playing here. It's not something silly like a bisolvent is it?


Ethanol is playing the role of a solvent. It is solvating the water and halogenalkane. I am not aware of it being given a special name and I asked my lecturers and they didnt know of a special name for such a solvent and they are not aware of the term "bisolvent."

Ethanol is a type of oxygenated solvent also known as a polar protic solvent. That is because the electronegative oxygen atom gives a slight polarity to the bond therefore enabling it to surround other polar molecules and dissoving them. [Also the non polar CH3CH2 part can dissolve the non polar region of the halogenalkane].

I hope that is of some use to you. Admittedly I was quite stuck by your question all day.
Sat in a lab, curing diseases. They actually LET me play with chemicals!
#36
i dont believe you guys. you all are full of it. kiss my black ssa
F' IT
(whats the worst that could happen)
#37
Quote by Guitardude19
Ethanol is playing the role of a solvent. It is solvating the water and halogenalkane. I am not aware of it being given a special name and I asked my lecturers and they didnt know of a special name for such a solvent and they are not aware of the term "bisolvent."

Ethanol is a type of oxygenated solvent also known as a polar protic solvent. That is because the electronegative oxygen atom gives a slight polarity to the bond therefore enabling it to surround other polar molecules and dissoving them. [Also the non polar CH3CH2 part can dissolve the non polar region of the halogenalkane].

I hope that is of some use to you. Admittedly I was quite stuck by your question all day.


I'm starting to doubt whether he (mychemistry teacher) actually did use a specific term now, but I'll ask him anyway. Thanks for explaining how things are dissolved by ethanol. I didn't need to put the process by which things are dissolved, simply why I needed them dissolved in the first place. It's interesting regardless.

Quote by MANNN
i dont believe you guys. you all are full of it. kiss my black ssa


I hope something mildly unpleasant happens to you, like a brussels sprout gets dropped on your head.
#38
Quote by Robbie n strat
I don't know whether I'll get much of an answer at this time (being as late as it is), though hope springs eternal. The question is this: If a solvent (in this instance ethanol) is used to bring together two chemicals which normally wouldn't mix (water and an halogenoalkane), what name is given to such a solvent?

I'm just writing why I would use ethanol in the nucleophilic substitution of an halogenoalkane (1-iodobutane, 1-bromobutane and 1-chlorobutane). I know why, and I'd get the marks for explaining why, but my chemistry teacher used a term a few weeks ago which describes the role ethanol is playing here. It's not something silly like a bisolvent is it?


ah, I remember something like that. I have to run for dinner now, but I'll look into it later. Something like phase transfer solvent, if I remember correctly. I remember it from nanotechnology lectures.

I'll get back to you (if I don't, PM me).
I'm an idiot and I accidentally clicked the "Remove all subscriptions" button. If it seems like I'm ignoring you, I'm not, I'm just no longer subscribed to the thread. If you quote me or do the @user thing at me, hopefully it'll notify me through my notifications and I'll get back to you.
Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
#39
(I can't edit posts with quotes in them or my computer will crash, sorry for the double post)

Right, I found my notes, they weren't in the nanotechnology notes, but in a different module by the same lecturer.

Anyway, turns out the stuff I had notes on was using a carrier molecule/catalyst (or contact ion pair) to transport stuff across liquid phases, not a solvent- though phase transfer is the correct term.

I couldn't find anything specific on Wiki about phase transfer solvents, but phase transfer is certainly a correct term. Maybe you can put the two together.

http://en.wikipedia.org/wiki/Phase_transfer_catalyst

http://en.wikipedia.org/wiki/Special:Search?search=phase+transfer+solvent
I'm an idiot and I accidentally clicked the "Remove all subscriptions" button. If it seems like I'm ignoring you, I'm not, I'm just no longer subscribed to the thread. If you quote me or do the @user thing at me, hopefully it'll notify me through my notifications and I'll get back to you.
Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
#40
Quote by Dave_Mc
(I can't edit posts with quotes in them or my computer will crash, sorry for the double post)

Right, I found my notes, they weren't in the nanotechnology notes, but in a different module by the same lecturer.

Anyway, turns out the stuff I had notes on was using a carrier molecule/catalyst (or contact ion pair) to transport stuff across liquid phases, not a solvent- though phase transfer is the correct term.

I couldn't find anything specific on Wiki about phase transfer solvents, but phase transfer is certainly a correct term. Maybe you can put the two together.

http://en.wikipedia.org/wiki/Phase_transfer_catalyst

http://en.wikipedia.org/wiki/Special:Search?search=phase+transfer+solvent


That sounds familiar.