Magnesium Hydroxide and Hydrochloric Acid (Antacid)

Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O

Overview

Magnesium hydroxide (milk of magnesia) neutralizes hydrochloric acid to form magnesium chloride and water. This is exactly the reaction that occurs in the stomach when antacid tablets are taken. Magnesium hydroxide is a mild base that neutralizes acid without causing rebound acidity.

Participants

Role	Substance	Coefficient	State
Reactant	Magnesium Hydroxide Mg(OH)₂	1	(s)
Reactant	Hydrochloric Acid HCl	2	(aq)
Product	Water H₂O	2	(l)

Everyday Example

Milk of magnesia antacid works by this reaction, neutralizing excess stomach acid (HCl) to relieve heartburn and indigestion.

Industrial Importance

Magnesium hydroxide is used in antacid formulations, as a fire retardant in plastics, and in wastewater treatment for heavy metal removal.

Properties

Type: Double Replacement
Reversible: No
Energy: Exothermic
ΔH: -108.0 kJ/mol

Related Reactions

Aluminum Hydroxide and Hydrochloric Acid Ammonia and Hydrochloric Acid (White Smoke) Barium Chloride and Sodium Sulfate Precipitation Calcium Carbonate and Hydrochloric Acid Calcium Chloride and Sodium Carbonate Calcium Hydroxide and Carbon Dioxide (Limewater Test) Calcium Hydroxide and Sulfuric Acid Copper(II) Sulfate and Sodium Hydroxide Iron(III) Chloride and Sodium Hydroxide Lead Nitrate and Potassium Iodide (Golden Rain)

Frequently Asked Questions

What is the equation for Magnesium Hydroxide and Hydrochloric Acid (Antacid)?

The balanced equation is: Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O.

What type of reaction is Magnesium Hydroxide and Hydrochloric Acid (Antacid)?

Magnesium Hydroxide and Hydrochloric Acid (Antacid) is a double replacement reaction.

Is Magnesium Hydroxide and Hydrochloric Acid (Antacid) exothermic or endothermic?

Magnesium Hydroxide and Hydrochloric Acid (Antacid) is exothermic (releases energy). The enthalpy change (ΔH) is -108.0 kJ/mol.