# In antacids like Eno that fizz up when mixed in water, why is the citric acid important?

I know that you can get rid of the acidity if you just take some baking soda added in water. I learned that these antacids that fizz up also have some citric acid and they react when added in water and produce $$\ce{CO2}$$ along with some other compound. I like to know the use of citric acid in an antacid. Is it just for the feel of the fizz that subliminally reminds us of fixing the acidity in stomach?

• To make bubbles... – Mithoron Nov 16 '17 at 21:12

It's the citric acid that reacts with the sodium bicarbonate. When the tablet hits the water, the citric acid and bicarbonate react, forming $\ce{CO2}$ and sodium citrate. This causes the tablet to break up, thereby much speeding up its dissolution.