A sample of a hydrate of barium chloride weighing 61 g has heated until all the hydration is removed. The dried sample weighed 52 g. The formula of hydrated salt is (atomic mass and Ba = 137 and Cl = 35.5)

1. BaCl2.H2O
2. BaCl2.2H2O
3. BaCl2.3H2O
4. BaCl2.4H2O

Dear Student,

Please find below the solution to the asked query:

On heating the water of crystallisation loses from the sample leaving behind the anhydrous salt, hence

Mass of water left = 61 - 52 = 9 g
Moles of water = 9 g / 18 g mol-1​ = 0.5 moles

Similarly, the moles of anhydrous BaCl2 will be = 52g / 208 g mol-1​ = 0.25 moles

Now, by dividing moles of water by moles of ​BaCl2 we will have the value of water of crystallization = 0.5 / 0.25 = 2

Hence, the formula is = ​​BaCl2.2H2O i.e. option (2).



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