# Homework Help: Help with experiment recording

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1. Oct 6, 2014

### Ziliba

Hello!
I need a little help! At school we did an experiment. We took cooper sulphate (CuSO4.5H2O) and heated it.Then we tried to see whether there are five moles of water to each mole of cooper sulphate.
I am asked to "start with a brief statement of how the experiment allowed you to determine the value of n and the assumptions made".
Maybe, someone can explain me what do they need from me? I don't understand.

2. Oct 6, 2014

### Staff: Mentor

Was it a full procedure, or were there operations that you have not listed?

3. Oct 7, 2014

### Ziliba

Nope.
We took hydrated cooper sulphate,measured it, heated it, measured again, calculated the mass of water, turned everything in moles, saw the ratio.

4. Oct 7, 2014

### Ziliba

Nope.
We took hydrated cooper sulphate,measured it, heated it, measured again, calculated the mass of water, turned everything in moles, saw the ratio.

5. Oct 7, 2014

### Staff: Mentor

By my book "measurement" qualifies as an operation that is part of the procedure, you have not listed it in your original post - just just said "we heated it".

So, what kind of a measurement it was? Length? Time?

6. Oct 7, 2014

### Ziliba

Sorry! I'm not used to writing about such things(
We measured the mass of hydrated sulphate, then we measured the mass of dehydrated cooper sulphate.
m(H2O)=m(hydrated CuSO4) - m(dehydrated CuSO4)
then we converted m(H2O) and m(dehydrated CuSO4) into moles.
then we found the ratio n(CuSO4):n(H2O)

7. Oct 7, 2014

### Staff: Mentor

So you assumed mass lost was that of the water lost, and based on this assumption you found molar ratio of water to copper sulfate?

8. Oct 7, 2014

......Yes

9. Oct 7, 2014

### Staff: Mentor

And you still don't know what to write? ;)

10. Oct 7, 2014

### Ziliba

The experiment above allowed me to determine the ratio between the cooper sulphate and the water by measuring the mass of cooper sulphate before and after heating (We assumed that the mass lost was that of the water lost).

11. Oct 7, 2014

### Ziliba

I just... Chemistry here is so different than in my country oo)

12. Oct 7, 2014

### Staff: Mentor

Would be enough for me.

13. Oct 7, 2014

### Staff: Mentor

Chemistry is the same, teaching can be different.

14. Oct 7, 2014

### Ziliba

No! Half of the things which are considered to be very important here are not even mentioned in my country!

Anyway, thank you very much!! I'm happy now:)