because CO2 is a gas and in its presence we can\'t measure the quantity of stomach acid (which is a liquid) that can be neutralized. In its presence we will get wrong value because it can react with bases easily. So we remove it to get the accurate value. Solution because CO2 is a gas and in its presence we can\'t measure the quantity of stomach acid (which is a liquid) that can be neutralized. In its presence we will get wrong value because it can react with bases easily. So we remove it to get the accurate value..