Chemistry homework

Question

Iron(II) sulfate forms several hydrates with the general formula FeSO_4•xH_2O where x is an integer If the hydrate is heated, the water can be driven off leaving pure FeSO_4 behind .

Suppose a sample of a certain hydrate is heated until all the water is removed, and it's found that the mass of the sample decreases by 11.%. Which hydrate is ? That is , what is x?

Answer 1

we know that the mass of the hydrate is 11% of the mass of the whole thing.

molar mass H2O= 18.015

molar mass feso4= 151.908

mass entire compound= 151.908 + 18.015x

mass of hydrate= 18.015x

18.015x/151.908+18.015x=.11

solve for x and you get that x = about 1