Question

given the five commercial products mentioned in the write up, Tums, Buffered aspirin, milk of Magnesia, Rolaids and Alka Seltzer, which would you expect to be more effective on mass basis to neutralize stomach acid? Back your reasoning with pertinent calculations.

Answer 1

Antacids are compound that neutralize the stomach acid

Take each tablet in turn - say you start with Tums.

Determine its composition. Then start to work out how much HCl the tablet can neutralise.

You then do this for each tablet in turn.

I will do this using the data of my own tablet:

Molar mass CaCO₃ (tums) = 100g/mol
Molar mass MgCO₃ = 84 g/mol

680mg CaCO₃ =0.680/100 = 6.8*10^-3 mol CaCO₃
80mg MgCO₃ = 0.080/84 = 9.52*10^-4mol MgCO₃

From your balanced equation you will see that 1 mol CaCO₃ reacts with 2mol HCl
6.8*10^-3 mol CaCO₃ reacts with 2*6.8*10^-3 = 1.36*10^-2 mol HCl
Likewise, for MgCO₃
9.52*10^-4 mol MgCO₃ reacts with 2*9.52*10^-4 = 1.904*10^-3 mol HCl

1 tablet will react with (neutralise):
1.36*10^-2 + 1.904*10^-3 = 1.55*10^-2 mol HCl

Molar mass HCl = 36.5g/mol
1.55*10^-2mol = 36.5* 1.55*10^-2 = 0.566g HCl.

1 of my antacid tablets will neytralise 0.556g HCl

Now you go ahead and do exactly the same for your antacid tablets.

If Tums regular. I found: Active Ingredients: Calcium Carbonate USP (500 mg) (Antacid).

This is a simple exercise:
500mg CaCO₃ = 0.500/100= 5.0*10^-3mol CaCO₃
This will netralise = 1.0*10^-2 mol HCl
Molar mass HCl = 36.5g/mol:
1*10^-2mol = 0.365 g HCl

Same do with milk of Magnesia( Mg(OH)₂),and Alka Seltzer (KHCO₃ and NaHCO₃)