#1
Nvm, found all the answers.

Thanks pit
The best thing about life is knowing you put it together
Last edited by MetalMegaMan at Jun 3, 2008,
#3
Haha, I understand why you don't, it's boring as ****.

I actually had to learn it all from Wikipedia due to unreliable books and teachers. It seems to be working out for me though.
The best thing about life is knowing you put it together
#5
Quote by MetalMegaMan
I don't feel like looking up in my unreliable Chemistry book



I'm guessing the book is more realiable than the pit....
Still awaiting his invitation to the coalition of intelligent pit users....

How many kids with ADD does it take to change a lightbulb?



Lets go ride our bikes
#7
Quote by Pyrest
Do your own homework dumbass.


no!
The best thing about life is knowing you put it together
#8
Quote by paul_brownell
I'm guessing the book is more realiable than the pit....


Actually the book is like 6 years old. Chemistry changes all the time, it's not like history or biology. I need an updated book but the school fails too much to get new ones.
The best thing about life is knowing you put it together
#9
for 3
P(1)/T(1)= P(2)/T(2)
810.6/343=P(2)/293
P(2)=692.44 KPa

that's by ideal gas law
question 4 is the 1 mole one i think

EDIT: Question 1 you just use the moles of water because the ratio of water to the NaOH it produces is even. so its just Mass=moles*Molecular weight
=3*39.998=120g
^Note: Probably sarcastic
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Quote by crisisinheaven
Deep*Kick. You have destroyed every concept of life I've ever had.
Last edited by Deep*Kick at Jun 3, 2008,
#10
I just found my periodic table lol. i just need help with 2 now.
The best thing about life is knowing you put it together
#11
Quote by MetalMegaMan
I'm finishing up a review for chemistry finals and I need some help with a few questions. Most of these I know but not 100% sure about. I don't feel like looking up in my unreliable Chemistry book


1. Given the Reaction: 2Na + 2H(2)0 --> 2NaOH + H(2)

How many grams of sodium hydroxide, NaOH, are produced from 3.0 mol of water?

a. 40g
b. 80g
c. 240g
d. 120g

3 moles of water give rise to 3 moles of NaOH as the equation says. 3 mol * (23+16+1) gram/ mol = 120 gram


2. Given the Reaction: 2Na + 2H(2)0 --> 2NaOH + H(2)

Calculate the percent yield if 80g of water react with excess sodium to produce 4.14g of hydrogen.

a. 89%
b. 92%
c. 87%
d. 98%
4.14 gram of H2 is roughly 2 mol thefore you shouldve used up 4 mole of water => 4 * 18 = 74 gram 74/80 = 92%


3. The pressure of a sample of gas at a constant volume is 8.0 atm at 70 degrees C. What is the pressure at 20 degrees C?

a. 0.16
b. 6.8
c. 9.4
d. 58

cant be arsed, other dude give it a go

4. How many moles of ions are produced by the dissociation of 1 mol oh HNO(3)?

a. 0
b. 1 mol
c. 2 mol
d. 3 mol

HNO3 + H20 <=> H3O+ + NO3- so two moles assuming full dissociation

Alright that's it..


^^
#12
just for that im not doing 2
^Note: Probably sarcastic
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W.A musicians FTW
Quote by crisisinheaven
Deep*Kick. You have destroyed every concept of life I've ever had.
#13
you#re going to stuggle with your papers if you can't do this

1) in the reaction 2mols water -> 2mol NaOH
so 3mol water -> 3 mol NaOH
mass of 1 mol NaOH = 23 + 16 + 1 = 40g
so mass 3mol = 40*3 = 120g

2) 1 mol water = 18g
so 80g is 80/18 = 4.44... mols
in the reaction 2mols water -> 1mol H(2)
so 4.444 mols -> 2.22 mols H(2)
1 mol H(2) weighs 2g
2.22 mols weighs 4.44g
since 4.14g are made
%= (mass made/mass expected)*100 = (4.14/4.44)*100

3) formula you NEED TO KNOW is PV=nRT
pressure*volume=number mols*8.31*temp
V, R, n don't change
so P=kT (where k needs to be worked out)
P=8 , T=340
so k=(8/340)
so when T=290
P=(8/340)*290

4) HNO(3) is a strong acid, (nitric acid) so fully dissociates into ions in water
When HNO(3) dissociates it forms 2 ions
HNO(3) -> NO(3)- and H+
so 1 mol HNO3 forms 2 mols of ions

hope that helps
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Last edited by doive at Jun 3, 2008,
#14
the book is only 6 years old, only really high end chemistry changes rapidly, this lot has been kicking around for about 100 years...
anything you get taught in school science is at least 30 years old, history changes far more quickly than that as it moves with political tides
The only 6 words that can make you a better guitarist:

Learn theory
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#16
Haha wait till you have to do organic chemistry, and chemical equilibria.

D-U-F-R-A-I-S


Quote by darkstar2466
WRONG.

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