In the experimental setup for the estimation of carbon and hydrogen, what would be the effect on the — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Concentrated $KOH$ is a strong alkali and highly hygroscopic; it absorbs both $CO_2$ and $H_2O$ vapor. If placed first, it will absorb all the water and carbon dioxide, leading to a falsely high mass increase for the $KOH$ tube (which is used to calculate $\%C$). Consequently, the $CaCl_2$ tube placed afterward will receive little to no water, resulting in an anomalously low calculated $\%H$.