A sample of an organic compound weighing is completely combusted in a stream of oxygen over hot . Th — Qualitative and Quantitative Analysis Chemistry Question
Question
A sample of an organic compound weighing $0.40 \text{ g}$ is completely combusted in a stream of oxygen over hot $CuO$. The evolved gases are passed through a concentrated $KOH$ solution, resulting in a mass increase of exactly $0.88 \text{ g}$. Calculate the percentage of Carbon present in the given organic compound.
💡 Solution & Explanation
The mass increase of the $KOH$ tube corresponds to the mass of $CO_2$ absorbed. Mass of $CO_2 = 0.88 \text{ g}$. The formula for $\%C$ is: $\%C = \frac{12}{44} \times \frac{\text{Mass of } CO_2}{\text{Mass of compound}} \times 100$. Substituting the values: $\%C = \frac{12}{44} \times \frac{0.88}{0.40} \times 100$. Simplifying: $\frac{12}{44} \times 2.2 \times 100 = 12 \times \frac{2.2}{44} \times 100 = 12 \times 0.05 \times 100 = 60\%$.