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# Chemistry C5 - Percentage Composition and Empirical Formula help watch

1. I've got a few questions and want to confirm if the answers are correct.

Question - Only question 13
Working out

All the images are attached in POST #4

Sorry guys, if my working out is unclear. I've written up my answers onto a word document and made a slight change in part (c) where I found a mistake in my working out and I've realised that I've changed the answer to something else which is hopefully correct.
I've only got my answers in this new picture - not the questions.
2. (Original post by Chittesh14)
I've got a few questions and want to confirm if the answers are correct.

Attachment 471843 = Question = Only question 13
Attachment 471841 = Working out

Sorry guys, if my working out is unclear. I've written up my answers onto a word document and made a slight change in part (c) where I found a mistake in my working out and I've realised that I've changed the answer to something else which is hopefully correct.
I've only got my answers in this new picture - not the questions.

Attachment 471851
I'd like to help, but none of your links seem to work.
3. (Original post by pineneedles)
I'd like to help, but none of your links seem to work.
They work for me and possibly I've uploaded them from the iPad. I'll re-upload them on the computer now if the error doesn't occur -_-.
4. (Original post by pineneedles)
I'd like to help, but none of your links seem to work.
Here you go
Attached Images

5. (Original post by Chittesh14)
Here you go
so you had no. of moles in the order of 3.225, 16.2 and 3.22.
to find the empirical formula you divide it by 3.22 which is the smallest out of 3.
so you get: 3.225/3.22=1.00... or 1
16.2/3.22=5.03... or 5
3.22/3.22=1
basically you get decimal numbers and you round those no. because empirical formula is the simplest ratio and written in whole numbers and not in decimal.
don't think too much and you wrote 3.222 that's wrong because the original ans is 3.2214 and 4 is smaller than 5 so it will be 3.221 not 3.222.
6. (Original post by bakastudent)
so you had no. of moles in the order of 3.225, 16.2 and 3.22.
to find the empirical formula you divide it by 3.22 which is the smallest out of 3.
so you get: 3.225/3.22=1.00... or 1
16.2/3.22=5.03... or 5
3.22/3.22=1
basically you get decimal numbers and you round those no. because empirical formula is the simplest ratio and written in whole numbers and not in decimal.
don't think too much and you wrote 3.222 that's wrong because the original ans is 3.2214 and 4 is smaller than 5 so it will be 3.221 not 3.222.
Sorry, done this at late night lol.
Anyway, thanks, I was wondering the same thing that since it would give a decimal and not a whole number, I should use a different number - 3.25. But, I've learnt something new :P that you just round it down to a whole number.

Posted from TSR Mobile
7. (Original post by bakastudent)
so you had no. of moles in the order of 3.225, 16.2 and 3.22.
to find the empirical formula you divide it by 3.22 which is the smallest out of 3.
so you get: 3.225/3.22=1.00... or 1
16.2/3.22=5.03... or 5
3.22/3.22=1
basically you get decimal numbers and you round those no. because empirical formula is the simplest ratio and written in whole numbers and not in decimal.
don't think too much and you wrote 3.222 that's wrong because the original ans is 3.2214 and 4 is smaller than 5 so it will be 3.221 not 3.222.
I've got a lot more questions to ask later on today, will you be able to help if I post them in like 2 hours :O?

Posted from TSR Mobile
8. (Original post by Chittesh14)
I've got a lot more questions to ask later on today, will you be able to help if I post them in like 2 hours :O?

Posted from TSR Mobile
if i can, sure.

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