Chem : Acids, bases and salts

anpanman SG

Doctors prescribe indigestion pills to reduce discomfort caused by excess stomach acidity. These tablets claim to cure excess stomach aciditry and contain the following active ingredients

CaCO3 and Al(OH)3

1. A short time after taking the pills, the patient "burps". Suggest a possible explanation.

I think the pills has "overworked" the neutralisation limit, causing the body system to become alkaline. Is it correct?

Hmm, I want to know what happens if you have too much stomach acid too. Do you have difficulties in digestion. If yes, how? thanks everyone

dkcx SG

CaCO3 is present in the tablet and you should have learnt that carbonates react with acids to give you CO2 which should be what causes the burping.

Too much stomach acid with no food leads to gastric and ulcers in the stomach when the acid starts to 'burn' the lining of your stomach. The presences of the acid is to create an acidic environment for the enzymes in your stomach to work as well as kill bacteria etc found in your food so it should have nothing to do with causing difficulties in digestion.

d3sT1nY SG

Funny, did they like put the Al(OH)3 there for no apparent reason? Or to sweep students off the road?

Anyway, this kind of question requires you to apply your chemistry knowledge into daily life activities. Like what the question says, to cure excess stomach acidity (you may not need to know that stomach fluids are actually acidic in this case).

So to cure high acidity, you must lower it. How to lower? By the normal acid-metal, acid-base, acid-carbonate reactions. In this case, it'll be the acid-carbonate reaction.

Simply saying, by removing the H+ (protons) from the stomach fluid (it may be a bit misleading), the pH of the fluid will increase, thus making it less acidic.

This question requires you to know which chapter is it talking about. Then from there, think of the answer in a logical way.

dkcx SG

Funny, did they like put the Al(OH)3 there for no apparent reason? Or to sweep students off the road?

Al(OH)3 is an amphoteric oxide so it will react with HCl in the stomach as well and help in the neutralisation effect. A tablet purely made of CaCO3 might be too basic or unsuitable for the body which could be a reason for the addition of Al(OH)3 to increase the effect without causing too much 'damage' to the stomach.

Do note that the acid also helps to induce hunger and if the stomach becomes alkaline, you will totally loss your appetite.