Calcium Hydroxide and Carbon Dioxide (Limewater Test)

Ca(OH)2 + CO2 → CaCO3 + H2O

Overview

Calcium hydroxide solution (limewater) turns milky white when carbon dioxide is bubbled through it, due to the formation of insoluble calcium carbonate particles. This is the classic test for carbon dioxide gas. With excess CO2, the milkiness disappears as soluble calcium bicarbonate forms.

Participants

Role Substance Coefficient State
Reactant Calcium Hydroxide Ca(OH)₂ 1 (aq)
Reactant Carbon Dioxide CO₂ 1 (g)
Product Calcium Carbonate CaCO₃ 1 (s)
Product Water H₂O 1 (l)

Everyday Example

The limewater test is taught in every introductory chemistry course as the standard qualitative test for carbon dioxide gas.

Industrial Importance

This reaction is used in flue gas desulfurization, carbon capture, and in the production of precipitated calcium carbonate for paper and paint industries.

Properties

Type
Double Replacement
Reversible
No
Energy
Exothermic
ΔH
-113.0 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 Sulfuric Acid Copper(II) Sulfate and Sodium Hydroxide Iron(III) Chloride and Sodium Hydroxide Lead Nitrate and Potassium Iodide (Golden Rain) Magnesium Hydroxide and Hydrochloric Acid (Antacid)

Frequently Asked Questions

What is the equation for Calcium Hydroxide and Carbon Dioxide (Limewater Test)?
The balanced equation is: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O.
What type of reaction is Calcium Hydroxide and Carbon Dioxide (Limewater Test)?
Calcium Hydroxide and Carbon Dioxide (Limewater Test) is a double replacement reaction.
Is Calcium Hydroxide and Carbon Dioxide (Limewater Test) exothermic or endothermic?
Calcium Hydroxide and Carbon Dioxide (Limewater Test) is exothermic (releases energy). The enthalpy change (ΔH) is -113.0 kJ/mol.