# Purify gas produced after reactions with sulfuric acid

Say, I preheat 50ml of 98% $\ce{H2SO4}$ and proceed with adding 25ml of 85% $\ce{HCOOH}$. The result of which is:

$$\ce{H2SO4 + HCOOH -> CO + H2O}$$

Sulfuric acid will dehydrate formic acid producing $\ce{CO}$, however, gas could still be contaminated with vapor. What is the correct way of removing these impurities?

Edit: To get rid of the acids present in the vapor, bubble the mixture through a concentrated base solution. Acids would react with the base, while $\ce{CO}$ being a neutral oxide, simply doesn't react and can be collected.