Question

The daily output of stomach acid (gastric juice) is 1000 to 2000 mL. Prior to a meal, stomach acid (HCl) typically has a pH of 1.38.

A.) What is the [H3O+] of stomach acid?

B.) One chewable tablet of the antacid Maalox contains 600. mg of CaCO3. Enter the neutralization equation.

C.) Given that one chewable tablet of the antacid Maalox contains 600. mg of CaCO3, calculate the milliliters of stomach acid neutralized by two tablets of Maalox.

D.) The antacid milk of magnesia contains 400. mg of Mg(OH)2 per teaspoon. Enter the neutralization equation.

E.) Given that the antacid milk of magnesia contains 400. mg of Mg(OH)2 per teaspoon, calculate the number of milliliters of stomach acid that are neutralized by 1 tablespoon of milk of magnesia. (1 tablespoon = 3 teaspoons.)

Answer 1

Sol :-

(a). Given , pH = 1.38

[H₃O⁺] = 10^-pH

[H₃O⁺] = 10^-1.38

[H₃O⁺] = 0.0417 M

(b). Balanced Chemical equation is :

CaCO₃ (s) + 2 HCl (aq) ---------------> CaCl₂ (aq) + CO₂ (g) + H₂O (l)

Moles of CaCO₃ per tablet = Mass/Gram molar mass = 0.600 g / 100 g/mol = 0.006 mol per tablet

Moles of H₃O⁺ neutralize by 2 tablets = 2 x 2 x 0.006 = 0.024 mol

0.024 mol/0.0417 mol/L = 0.576 L = 576 mL of stomach acid

(c). 2 HCl (aq) + Mg(OH)₂ (s) ------------------> MgCl₂ (aq) + 2 H₂O (l)

1 tablespoon = 3 tea spoon

1 teaspoon contains 400 mg of Mg(OH)₂ = 0.4 g

Moles of CaCO₃ per teaspoon = 0.4 g / 58.3 g/mol = 6.86 x 10^-3  

Moles of H₃O⁺ neutralize by 1 tablespoon = 2 x 3 x 6.86 x 10^-3 = 0.0411 mol

0.0411 mol/0.0417 mol/L = 0.986 L = 986 mL of stomach acid