The daily output of stomach acid (gastric juices) is 1000 mL to 2000 mL. Prior t

ID: 908132 • Letter: T

Question

The daily output of stomach acid (gastric juices) is 1000 mL to 2000 mL. Prior to a meal, stomach acid (HCl) typically has a pH of 1.42.

a. Calculate the milliliters of stomach acid neutralized by two tablets of Maalox.

Express your answer to two significant figures and include the appropriate units.

b. Calculate the number of milliliters of stomach acid neutralized by one tablespoon of milk of magnesia (one tablespoon = three teaspoons).

Express your answer to two significant figures and include the appropriate units.

[H+] = 10^-pH = 10^-1.42 = 0.038 M

3HCl(aq) + Al(OH)3(s) --> AlCl3(aq) + 3H2O(l)

two tablets of Maalox means = 2 x 0.02 g = 0.04 g

moles of maalox tablet = 0.04 / 78 = 5.13 x 10^-4

3 moles of HCl = 1 mole of Al(OH)3

x mol of HCl = 5.13 x 10^-4

x = 1.538 x 10^-3

moles = 1.538 x 10^-3

molairty x volume = 1.538 x 10^-3

0.038 x volume = 1.538 x 10^-3

volume = 0.04048L = 40.49 ml

40.49 ml stomach acid is neutralised

(b)

Mg(OH)2 = 400 mg per teaspoon

one tablespoon = three teaspoons = 3 x 400 mg = 1200 mg =1.2g

moles = mass / molar mass = 1.2 / 58.31 = 0.0206

moles of HCl = 2 x 0.0206 = 0.0412

0.038 x volume = 0.0412

volume = 1.083 L = 1083 ml

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