Percent composition Knowledge-Based Download PDF

Questions

1. 1.

   What mass of calcium is contained in a 250.0 g sample of pure calcium carbonate, $\text{CaCO}_3$? (Molar masses: $\text{Ca} = 40.08\text{ g/mol}$, $\text{C} = 12.01\text{ g/mol}$, $\text{O} = 16.00\text{ g/mol}$)

   • A) 30.0 g
   • B) 40.0 g
   • C) 120.0 g
   • D) 100.1 g
2. 2.

   Which of the following compounds contains the highest percent by mass of sulfur? (Molar masses: $\text{H} = 1.01\text{ g/mol}$, $\text{C} = 12.01\text{ g/mol}$, $\text{O} = 16.00\text{ g/mol}$, $\text{S} = 32.07\text{ g/mol}$, $\text{Fe} = 55.85\text{ g/mol}$)

   • A) $\text{H}_2\text{S}$
   • B) $\text{CS}_2$
   • C) $\text{SO}_2$
   • D) $\text{FeS}$
3. 3.

   What is the percent by mass of water in copper(II) sulfate pentahydrate, $\text{CuSO}_4 \cdot 5\text{H}_2\text{O}$? (Molar masses: $\text{Cu} = 63.55\text{ g/mol}$, $\text{S} = 32.07\text{ g/mol}$, $\text{O} = 16.00\text{ g/mol}$, $\text{H} = 1.01\text{ g/mol}$)

   • A) 7.22%
   • B) 25.45%
   • C) 56.45%
   • D) 36.08%
4. 4.

   A 3.50 g sample of iron reacts completely with excess oxygen to produce 5.00 g of an iron oxide. What is the percent by mass of oxygen in the product?

   • A) 70.0%
   • B) 42.9%
   • C) 17.6%
   • D) 30.0%
5. 5.

   What is the percent by mass of nitrogen in ammonium nitrate, $\text{NH}_4\text{NO}_3$? (Molar masses: $\text{N} = 14.01\text{ g/mol}$, $\text{H} = 1.01\text{ g/mol}$, $\text{O} = 16.00\text{ g/mol}$)

   • A) 17.5%
   • B) 28.0%
   • C) 60.0%
   • D) 35.0%