## Chemistry: Principles and Practice (3rd Edition)

Mass percentage of an element = (mass of that element in the compound × 100)/(molar mass of the compound) Molar mass of magnesium carbonate ($MgCO_{3}$) = $(1\times24.305g)+(1\times12.011g)+(3\times15.999g)$ = 84.313g Mass % of Mg = $\frac{(1\times24.305g)\times100}{84.313g}$ = 28.827% Mass % of C = $\frac{(1\times12.011g)\times100}{84.313g}$ = 14.246% Mass % of O = $\frac{(3\times15.999g)\times100}{84.313g}$ = 56.927%