Calculate the mass percentage of aspirin $(C_{9}H_{8}O_{4})$ in acetonitrile $(CH_{3}CN)$ when $6.5 \ g$ of $C_{9}H_{8}O_{4}$ is dissolved in $450 \ g$ of $CH_{3}CN$.

(N/A) The mass of the solute (aspirin,$C_{9}H_{8}O_{4}$) is $6.5 \ g$.
The mass of the solvent (acetonitrile,$CH_{3}CN$) is $450 \ g$.
The total mass of the solution is the sum of the mass of the solute and the solvent: $6.5 \ g + 450 \ g = 456.5 \ g$.
The mass percentage of $C_{9}H_{8}O_{4}$ is calculated as: $\frac{\text{mass of solute}}{\text{total mass of solution}} \times 100$.
Mass percentage $= \frac{6.5 \ g}{456.5 \ g} \times 100 \% \approx 1.424 \%$.