Question

barium chloride crystals contain 14.8% water of crystallisation.find the number of molecules of water of crystallisation per molecule.

Answer 1

Calculate Mol. Wt of BaCl₂ = 208 g (unhydrated)

Gms of water of hydration is 14.8 % of total hydrated weight

i.e. 14.8/100 = 100X / (208+X) where X = mass of water

= 0.148 = X/(208+X)

= 0.148 x (208+X) = X

Solving for X we get

X = 36.2 g

i.e. 36.2 g of water

Mol wt of water = 18 therefore there are 2 moles of water

Hydrated Barium chloride = BaCl₂.2H₂O