Question

in calcium carbonate (caco₃), what is the percent composition of oxygen? 47.95% 40.04% 48.00% 45.00%

Explanation:

Step1: Calculate molar mass of \(CaCO_3\)

Molar mass of \(Ca = 40.08\space g/mol\), \(C=12.01\space g/mol\), \(O = 16.00\space g/mol\).
Molar mass of \(CaCO_3=40.08 + 12.01+3\times16.00\)
\(=40.08 + 12.01 + 48.00=100.09\space g/mol\)

Step2: Calculate mass of oxygen in \(CaCO_3\)

There are 3 O atoms. Mass of oxygen \(=3\times16.00 = 48.00\space g/mol\)

Step3: Calculate percent composition of oxygen

Percent composition of oxygen \(=\frac{\text{Mass of oxygen}}{\text{Molar mass of }CaCO_3}\times100\%\)
\(=\frac{48.00}{100.09}\times 100\%\approx47.95\%\)

Answer:

\(47.95\%\)