Final answer:
The mass of water driven off when 1.252 g of strontium chloride hexahydrate is decomposed by heating is 0.5090 g.
Step-by-step explanation:
To find the mass of water driven off when strontium chloride hexahydrate is decomposed by heating, we first need to determine the molar mass of strontium chloride hexahydrate. Strontium chloride hexahydrate has a molar mass of 266.62 g/mol. The formula for strontium chloride hexahydrate is SrCl2 · 6H2O, which means the compound contains 6 water molecules (H2O) for every strontium chloride (SrCl2) unit.
Since 1.252 g of the compound is decomposed, we can find the mass of water driven off by subtracting the mass of SrCl2 from the total mass. The molar mass of SrCl2 is 158.53 g/mol, so the mass of SrCl2 in 1.252 g of the compound is (1.252 g) * (158.53 g/mol) / (266.62 g/mol) = 0.7430 g.
Therefore, the mass of water driven off when 1.252 g of strontium chloride hexahydrate is decomposed by heating is the difference between the total mass and the mass of SrCl2: 1.252 g - 0.7430 g = 0.5090 g.