Chemistry - Mole Concept Question with Solution | TestHub

Explain the Question : Determine the mass of Carbon ( C ) and Hydrogen ( H ) in a 25 g hydrocarbon sample, given that its combustion yields 88 g of ${\mathrm{CO}}_2$ and 9 g of ${\mathrm{H}}_2\mathrm{O}$.

Concept : This question is based on Stoichiometry (Mass of C in ${\mathrm{CO}}_2$ and Mass of H in ${\mathrm{H}}_2\mathrm{O}$ ).

Solution :

1. Mass of Carbon (C): Molar Mass (${\mathrm{CO}}_2$) = 44 g/mol.

Mass of C = 88 g ${\mathrm{CO}}_2$$\times$$\frac{12}{44}$ = 24 g.

Mass of Hydrogen (H): Molar Mass (${\mathrm{H}}_2\mathrm{O}$) = 18 g/mol.

Mass of H = 9 g ${\mathrm{H}}_2\mathrm{O}$$\times$$\frac{2}{18}$ = 1 g.

(24 g + 1 g = 25 g, matching the initial sample mass)