Question

$Calculatethenumberofmoleculesofwaterofcrystallisationincoppersulphatecrystals,if10gofhydrouscoppersulphatecrystalsgive6.4gofanhydrousCuS{O}_{4}onheating.$ [Cu=64, S=32, O=16]

Answer 1

Dear Student,

Value of mass of water obtained from heating of 10 g of hydrated copper sulphate is not given so by assuming it to be 3.6 g the value of water of crystallisation can be calculated as follows

Mass of CuSO4 = 160g
Mass of water = 18 g

$$\begin{gathered} \frac{\text{Mass of water}}{\mathrm{Mass}\mathrm{of}\mathrm{anhydrous}\mathrm{copper}\mathrm{sulphate}}\text{=}\frac{18\mathrm{X}}{160}\text{=}\frac{3.6}{6.4} \\ \text{X =}\frac{{\displaystyle 3.6\times 160}}{{\displaystyle 6.4\times 18}}\text{= 5} \\ \mathrm{So}\mathrm{number}\mathrm{of}\mathrm{water}\mathrm{of}\mathrm{crystallisation}\mathrm{is}5 \\ \mathrm{Regards} \end{gathered}$$