A 36.41-g sample of calcium carbonate (CaC O 3)

contains 14.58 g of calcium and 4.36 g of carbon.

What is the mass of oxygen contained in the sam-

ple? What is the percent by mass of each element in

this compound?

M (O) = m (CaCO₃) - m (Ca) - m (C).

m (O) = 36.41 g - 14.58 g - 4.36 g.

m (O) = 17.47 g.

ω (Ca) = m (Ca) : m (CaCO₃) · 100%.

ω (Ca) = 14.58 g : 36.41 g · 100%.

ω (Ca) = 40 %; mass percent of calcium.

ω (C) = m (C) : m (CaCO₃) · 100%.

ω (C) = 4.36 g : 36.41 g · 100%

ω (C) = 12%; mass percent of carbon.

ω (O) = 100% - ω (Ca) - ω (C).

ω (O) = 100% - 40% - 12%.

ω (O) = 48%; mass percent of oxygen.