Why is a solution of potassium hydroxide used to absorb carbon dioxide evolved during the estimation of carbon present in an organic compound?
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+CO2→K2CO3+H2O
Thus, the mass of the U-tube containing KOH increases. This increase in the mass of U tube gives the mass of CO2 produced. From its mass,the percentage of carbon in the organic compound can be estimated.