The Stomach: Acid-Base Chemistry

What is in the stomach? Good old hydrochloric acid. I have previously mentioned HCl can do some damage to your skin. But why then does it sit harmlessly in your stomach? This is because your stomach is lined with an acid resistant mucus. I say resistant because the mucus does need to be replenished and if it isn't, you start getting ulcers. 

But that mucus ends at your stomach. Your esophagus and your small intestine-the two pieces of your digestive system on either side of your stomach-do not have the mucus. This is why on those mornings after a night of drinking, and therefore a morning wrapped around the toilet, your throat may burn. That is because the acid burns the tissues as it makes a mass exit from your stomach. This is also why people with eating disorders that involve purging often has eroded teeth, gums, and other lesions in their mouth and throat. The continuous passage of acid over those tissues burns them, eventually leading to serious damage. Side note: while HCl can burn your tissues it would be a poor choice if you wanted to dissolve a dead body. 

So what can you do if the acid in your stomach gets to be too much of a problem? Neutralise it of course! What neutralises acids? Bases! Acid + Base = water + salt. This is always. And this is a very important reaction. To neutralise stomach acid, you don't want too strong of a base so sodium bicarbonate, NaHCO3, will work just fine.  HCl + NaHCO3 = NaCl (the salt) + H2CO3 (carbonic acid) which dissociates (quickly) into H2O (water) and CO2 (carbon dioxide). The CO2 is a gas and this is why taking an antacid may make you gassy. So if you want to buy an antacid, you can. But you can also just use the sodium bicarbonate you have in your cupboard. It is probably in box marked Arm and Hammer Baking Soda.