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# Chemistry Practicals

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1. It certainly is a bit late to ask this, but how do you treat hydrated molecules where the water is not in the molecule, but 'attached' to it (represented by X.H20)?

For example, a question that comes up much is on discovering how many molecules of water there are in a hydrated compound. An example is seen in Q1 of this paper: 9701 Summer 2011 32.

Thanks beforehand!
It certainly is a bit late to ask this, but how do you treat hydrated molecules where the water is not in the molecule, but 'attached' to it (represented by X.H20)?

For example, a question that comes up much is on discovering how many molecules of water there are in a hydrated compound. An example is seen in Q1 of this paper: 9701 Summer 2011 32.

Thanks beforehand!
Weigh the mass of the hydrated salt, evaporate all the water until the anhydrous salt remains, weigh by difference to find the mass of water.

Then find n of H20 used via mass/molecular mass

Then multiply the value of n by 6.02x10^23 (avogadro's constant) to find number of molecules).
It certainly is a bit late to ask this, but how do you treat hydrated molecules where the water is not in the molecule, but 'attached' to it (represented by X.H20)?

For example, a question that comes up much is on discovering how many molecules of water there are in a hydrated compound. An example is seen in Q1 of this paper: 9701 Summer 2011 32.

Thanks beforehand!
Hey there did u give v32 practical paper today?
4. (Original post by RasputinReborn)
Weigh the mass of the hydrated salt, evaporate all the water until the anhydrous salt remains, weigh by difference to find the mass of water.

Then find n of H20 used via mass/molecular mass

Then multiply the value of n by 6.02x10^23 (avogadro's constant) to find number of molecules).
Thanks, mate!

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