Which chemical equation represents CO2 absorption in the absorber?

• A. CO2 + H2O -> Carbonic Acid
• B. CO2 + O2 -> Carbon Monoxide
• C. CO2 + NaOH -> Sodium Carbonate
• D. H2O -> Hydrogen Gas

Answer: (A)

The key idea is that CO2 absorption into an aqueous absorber starts with CO2 dissolving in water to form carbonic acid. This initial dissolution, CO2 + H2O → H2CO3, represents CO2 entering the liquid phase and becoming carbonic acid, which can then dissociate further in the solution. This step is the fundamental depiction of how CO2 is captured by the absorber.

The other options describe processes that aren’t the basic absorption step: converting CO2 with oxygen to carbon monoxide, producing hydrogen gas from water, or CO2 reacting with a base like NaOH to form sodium carbonate. While CO2 can later react with bases in the absorber, the most direct representation of the absorption event itself is CO2 dissolving in water to form carbonic acid.