Why is solution of potassium hydroxide used to absorb carbon dioxide evolved during the estimation of carbon present in an organic compound?

Explanation

Carbon dioxide is acidic in nature and potassium hydroxide is a strong base. Hence, carbon dioxide reacts with potassium hydroxide to form potassium carbonate and water as
`2KOH+CO_(2)toK_(2)CO_(3)+H_(2)O`
Thus, the mass of the U-tube containing KOH increases. This increase in the mass of U- tube gives the mass of `CO_(2)` produced. From its mass, the percentage of carbon in the organic compound can be estimated.