Question

a 10.00 gram sample of the hydrated salt cacl2. x.h2o was thermally decomposed by anhydrous calcium chloride and water vapours find the no. of water molecules in the salt

Answer 1

moles of Cacl2 $= \frac{ 7.93}{110.98} = 0.0715 mole.$

The loss of water amounts to 10 g - 7.93 g = 2.07 grams of water.

H2O moles $=\frac{2.07 }{ 18 } = 0.115 mole.$

The ratio of water to cacl2 (which is what ‘x’ means in K2CO3xH2O) is equal to:

Ratio $=\frac {0.115}{0.0715}=1.6 = 2$

So, x is 2 and the formula is $CaCl_2. 2H_2O$