Question

0.400 g of impure CaSO4 (Molar mass = 136) solution when treated with excess of barium chloride solution, gave 0.617 g of anhydrous BaSO4 (Molar mass = 233). The percentage of CaSO4 present in the sample is

• (A) 80.0%
• (B) 90.0%
• (C) 95.0%
• (D) 75.0%

Answer 1

The Correct Option is B

Explanation:
${\mathrm{CaSO}}_{4(\mathrm{ag})}+{\mathrm{BaCl}}_{2(\mathrm{aq})}\to {\mathrm{BaSO}}_{4(\mathrm{s})}+{\mathrm{CaCl}}_{2(\mathrm{ag})}$$136\mathrm{g}{\mathrm{caSO}}_4$ produces $233\mathrm{g}$ BaSO ${}_4$Weight of ${\mathrm{BaSO}}_4=0.617\mathrm{g}$Mass of ${\mathrm{CaSO}}_4$ reacted $=\frac{0.617\times 136}{233}=0.3601\mathrm{g}$Percentage purity of ${\mathrm{CaSO}}_4$ $=\frac{0.3601\times 100}{0.400}=90.025$