People often take milk of magnesia to reduce the discomfort associated with acid stomach or heartburn. The recommended dose is 1 teaspoon, which contains 4.00×102 mg of Mg(OH)2. What volume of an HCl solution with a pH of 1.3 can be neutralized by one dose of milk of magnesia? If the stomach contains 2.00×102 mL of pH 1.3 solution, is all the acid neutralized? If not, what fraction is neutralized?

- Volume of HCl = 270mL

- Yes, all the acid will be neutralized

Explanation:

HCl + Mg(OH)2 ⇌Mg(Cl)2 + 2(H2)O

First of all, we must assume that strong acids dissociate.

Thus, we can obtain the concentration of hydrochloric acid in the stomach,

10^(-ph) = [H+]

From the question, PH = 1.3

So, [H+] = 10^(-1.3) = 0.05M

In the question, we are given information to support the neutralization of excess hydrochloric acid via milk of magnesia, which contains Mg(OH)2

Thus, one molar equivalent of hydrochloric acid will be neutralized by the moles of hydroxide ions that make it to the stomach acid solution and dissociate from Mg(OH)2.

Molar mass of Mg(OH)2 = 58.3

So,

400mg Mg(OH)2 x (1g/(10^(-3)mg) x (1 mol/58.3g) x ( (2mol HCl) /(1 mol Mg(OH)2) x (1 L/0.05 mol HCL) x ((10^(3)ml)/1L = 270ml HCl

Therefore, one teaspoon of Mg(OH)2 will be sufficient to completely neutralize 200ml of the acid.