FlynnXD
When concentrated nitric acid is produced, a part of it decomposes as: 4HNO3--> 4NO2 + 2H2O + O2 This NO2 dissolves in the solution and produces a yellow colour.
To remove this, CO2 is bubbled in, which shifts the liquid-vapour equilibria of NO2, and removes it from solution, which gets oxidized and forms HNO3 again, thus the yellow colour is removed.
Answers & Comments
4HNO3--> 4NO2 + 2H2O + O2
This NO2 dissolves in the solution and produces a yellow colour.
To remove this, CO2 is bubbled in, which shifts the liquid-vapour equilibria of NO2, and removes it from solution, which gets oxidized and forms HNO3 again, thus the yellow colour is removed.