Formula of compounds

[mollykins]

Yes this is for homework BUT i'm not asking you to do the questions for me, i'm asking how you do them, so once i've got the method i'll work them out myself.

If you're given the wieght of three elements, that make up a compound, how do you work out the formula? I've done it for the one's that only have two elements in them but I got on this one.

Plus if you're given the the percentage (not integers) of three elements that make up a compound, how do you work out the formula? I have a feeling that it involves relative atomic mass . . .

[mike11111]

Now your'e gonna confuse the girl!

[jomifl]

Hi Molly, the figures that you posted up work out OK, when you have divided the weight (or percentage) of element by the atomic weight you end up with the ratios of the numbers of atoms in each compound. These need to be whole numbers. You have to divide each of the ratios by the smallest ratio, this should give you whole numbers. For example in question 1 the smallest is the value for Sulphur, divide all 3 values by the value for sulphur(including the value for sulphur) and you will get the formula for a well known acid. Good luck with the rest.

[anneasquith]

the answer is x.

[bobjugs12]

Errrrrrr......hmmmmmm.........nope, still haven't got the foggiest

[blackeyed]

vow!
she's sure gonna get confused now!!!
one reason i think more than twice before posting on AB!

[mike11111]

"I have a feeling that it involves relative atomic mass . . .". Who says education has been dumbed down?"

[blackeyed]

@ gen 2 molecules can become ions there just has to be an imbalance between the protons and neutrons for example: zwitter ion

[blackeyed]

sorry electrons not neutrons

[gen2]

blackeyed, I'm sure zwitterions will not feature in AS level chemistry, but (unless it has been seriously dumbed down since the 1960s), partial ionisation should be covered as it is essential to understanding pH and buffering.

[blackeyed]

just re-read the sorry i took it in some other way.
It would be as you say if the substance is a compound.

[mollykins]

H2SO4 if I remember it correctly. I handed it in today and the teacher did say we needed to find out empirical formulae for those questions, thanks guys.

But I managed to answer everything thanks for all your help.

We did about ionisation in gcse triple science.

[johnheritage]

Well Gen2, that's were you, and a very large percentage of the adult population, are incorrect. As Zwitterions are covered.

I'm sick to death of hearing from older people about how dumbed down science and maths is now. It must be a strange form of dumbing down that creates the microprocessors you're typing that message on.