Finding x in Fe(NH4)2(SO4)2·xH2O from BaSO4 precipitate

[CSG18]

Insert Quote
Hi, I would be very grateful if anyone could show me how to answer the following question:

The value of x in Fe(NH4)2(SO4)2. xH2 O can be found by determining the amount in moles of sulfate in the compound.
A 0.982g sample was dissolved in water and excess BaCl2 (aq) was added.
The precipitate of BaSO4 was separated and dried and found to weigh 1.17g.

(a) Calculate the amount, in moles, of sulfate in the 0.982g sample of Fe(NH4)2(SO4)2. xH2O

(according the the answers it's 0.00501 which I do not understand)

(b) Calculate the amount, in moles, of iron in the 0.982g sample of Fe(NH4)2(SO4)2. xH2O

(apparently the answer is 0.00250 which is half of the previous answer - why?!)

Thanks in advance.

 

[Borek]

You have asked the same question at CF and you were already given hints there, nobody is going to solve the question for you.

 

[CSG18]

You have asked the same question at CF and you were already given hints there, nobody is going to solve the question for you.

The hints were wrong though. Its ok though, I understand it now.

 

[Borek]

The hints were wrong though.

They were perfect.