Question

The calcium supplements taken by many women are composed primarily of powdered calcium carbonate, CaCO_3, which is also the primary compoent of marble.

(a) Briefly expain why CaCO₃ would be a good source for a woman suffering from chronic heartburn. Use a net ionic equation.

(b) Marble statues erode when exposed to acidic precipitation. Give a brief chemical explanation for this erosion.

(c) Briefly explain why many people prefer antacids in which Mg(OH)₂ is the active ingredient over those that use use CaCO_3.

Answer 1

(a) Heartburn is an irritation of the esophagus that is caused by stomach acid (HCl). This can create a burning discomfort in the upper abdomen or below the breast bone.

CaCO3 which is a basic substance can neutralize the acid responsible for the heartburn

CaCO3 + 2HCl = CaCl2 + CO2 + H2O Molecular equation

CaCO3 + 2H⁺ + 2 Cl^- = Ca⁺⁺   + 2 Cl^-  + CO2 + H2O Ionic eqation

Cancelling the 2Cl - ions common to both sides the net ionic equation is

CaCO3 + 2H⁺ = Ca⁺⁺   + CO2 + H2O Net ionic equation

b) A similar reaction is responsible for the erosion of marble statues.as CaCO3 is the primary component of marble.

CaCO3 + 2H⁺ = Ca⁺⁺   + CO2 + H2O Net ionic equation

c)

MAGNESIUM HYDROXIDE has a much lesser incidence of serious side effects because

1. it has a high efficiency in neutralization reaction and
2. a low systemic absorption( This lowers the chance of metabolic alkalosis.)

That’s why many people prefer antacids in which Mg(OH)₂ is the active ingredient over those that use CaCO_3.