[Soulshine]

We just did a lab on water hydration, and there's this one question that I'm finding too difficult to answer. I don't even know how to start it.
Here's the question: A student found the percent of H2O in ZnSO4 ( dot in the middle) 7H2O. Determine the experimental error. 

[Astrokel]

A student found the percent of H2O in ZnSO4 ( dot in the middle) 7H2O.

I don't quite get this part, you mean a student found the percentage of H₂O in ZnSO₄.H₂O? and so what is this percent?

[macman104]

So someone determined the percent H2O and you need to determine the experimental error (since you can calculate the theoretical value).

What type of percent did they determine?  I assume they determined the weight percent?

[JGK]

You can calculate the "actual" % of water in the molecule based on atomic weight

you have a % of water calculated experimentally.


You can calculate the ratio of experimental value to actual and express as a percentage (call this value "Q".


the percentage error = Q - 100.  If you're experimental value is low the number will be -ve , if high the value is +ve