How many tablets of antacid are needed to neutralize all of the gastric acid?

Question

A normal person produces about 2.8 L of gastric juices during the course of a day. If these fluids contain 3.4 g HCl per liter, how many tablets of antacid, containing 400 mg of Al(OH)3 each, would be needed to neutralize all of the gastric acid produced in one day?

Give your answer in whole tablets.

Example: If your calculation shows that 5.128 tablets are needed then put 6, since the pharmacy won't sell you 0.128 tablets!

Answer 1

2.8 litres  @ 3.4 grams HCl per litre = 9.52 grams of HCl

the reaction ratio is:

3HCl & 1 Al(OH)3 --> AlCl3  & 3 H2O

reacts:

3moles HCl @ 36.46 g/mol = 109.39 grams of HCl reacts with...

1 mole of Al(OH)3 @ 78.00 g/mol

therefor, calculate how many grams of HCl are needed:

9.52 grams HCL @ 78.00 g Al(OH)3 / 109.39g HCl = 6.79 grams of tablets are needed

find the # of tablets needed:

6.79 grams Al(OH)3 @ 0.400 grams Al(OH)3/tablet= 16.97 tablets

your answer is: 17 tablets

that is a lot of tablets, but antacid tablets are not intended to neutralize all of the acid, only that which is considered "excess stomach acid",... and that is why we feel relief with fewer tablets