The Action of Metal Carbonates with Acids and Bases

Explore how metal carbonates interact with acids and bases through characteristic chemical reactions – with real-world examples and balanced equations.

Introduction

Metal carbonates are an important class of compounds found both in nature (like limestone and chalk) and in daily life (like baking soda). Their reaction with acids is commonly used in laboratories and has significant industrial and environmental applications.

Typical Reaction of Metal Carbonates with Acids

When a metal carbonate reacts with an acid, it produces a salt, water, and carbon dioxide gas.

General Equation:
Metal Carbonate + Acid → Salt + Water + Carbon Dioxide (CO2)
  • Effervescence (Fizzing): The formation of CO2 gas causes visible bubbling.
  • Neutralization: The acid is neutralized as it forms a corresponding salt with the metal.

Illustrative Examples

1. Reaction of Calcium Carbonate and Hydrochloric Acid
CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + H2O (l) + CO2 (g)
  • Calcium carbonate is found in chalk, marble, eggshells, and limestone.
  • On contact with hydrochloric acid, fizzing occurs due to CO2 release.
2. Reaction of Sodium Carbonate and Sulphuric Acid
Na2CO3 (aq) + H2SO4 (aq) → Na2SO4 (aq) + H2O (l) + CO2 (g)

Key Points to Remember

  • Metal carbonates react only with acids, not with bases. This is because both carbonates and bases are of basic character, so no visible reaction occurs between them.
  • The reaction is used to test for the presence of carbonates. Bubbling gas is collected and if it turns limewater milky, it confirms CO2.

Everyday Applications

  • Limestone neutralization: In environmental science, crushed limestone (CaCO3) is used to neutralize acidic soils and lakes.
  • Limestone in building: Dilute acids can damage marble and limestone structures by reacting with calcium carbonate.
  • Baking soda (NaHCO3) in kitchen science: Used in some cleaning and cooking reactions where acids cause fizzing.

Summary Table

Reactants Products Observation
CaCO3 + 2HCl CaCl2 + H2O + CO2 Fizzing, Limewater turns milky
Na2CO3 + H2SO4 Na2SO4 + H2O + CO2 Effervescence

Learning Quiz

  • Why doesn’t sodium carbonate react with sodium hydroxide?
  • Which gas is released when a carbonate reacts with an acid?
  • What would you observe if you add vinegar (acetic acid) to baking soda?