Hey guys, I am really struggling with some science stuff. I would appreciate it of someone could help me out.

I am not asking for the answers as such, but help on how to do the problems. I have to had this assignment in tomorrow.

1. Rust is a product of a reaction between iron and oxygen. Iron however can form either a 2+ or 3+ ion.
Outline briefly an experiment you could carry out to determine whether rust is iron(II) oxide or iron (III) oxide.

2.A gas balloon contains 5.5 mol of helium. Calculate;
a. the mass of helium
b. the number of helium atoms in the balloom\\

I might need to post a couple more up too.

Thanks a million!
For number two, I believe you multiply 5.5 times the molecular mass.
Iron (ii) or Iron (iii)...I remember VAGUELY something about huge measuring cylinder and vaseline.

2. If He has a mass of 2 I think the mass is 10.5g
and I just threw all my chemistry notes out and have forgotten the next one.
ahh chemistry... i never have to do it again but i shall still attempt to help.

number of moles= (mass*1000)/volume timesd by concentration
2b I think is 5.5 times Avagadro's constant

also, I believe that metal4ever is correct
Last edited by circus musician at Jul 1, 2008,
Thanks guys. Any more specific explanations?

Also;

The common name for mothballs in napthalene. It contains 93.7% carbon and 6.3% hydrogen and has a molar mass of 128g mol^-1. Find the empirical formula and molecular formulae.

I can find the empirical one but not the other
I don't listen in Chemistry. My teacher is too hard to understand. I Got 49% on my half yearly. So close to a pass.

For the question I think you need Avogadro's number. 6.0221415 × 10^23

edit: Too late.
Damn chemistry, I hated it at GCSE and hate it now. Now, if you gave me Physics, thats whole other bottle of water
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To find the molecular formula from the empirical formula, add up the atomic masses in your empirical formula and divide the actual molar mass by that number. Then multiply everything in the empirical formula by the answer to that sum.
Quote by smb
To find the molecular formula from the empirical formula, add up the atomic masses in your empirical formula and divide the actual molar mass by that number. Then multiply everything in the empirical formula by the answer to that sum.

The answer to question one is to titrate a solution of the Fe ions with an oxidising agent (such as potassium manganate solution). If the solution turns colourless then Fe2+ ions are present, if nothing happens then Fe3+ ions are present.
Oh George... Oh George.

That Texas education must've fucked you up when you very small.

Too true, Roger. Too True.