Reactions of Sodium carbonate (Na₂CO₃)

Sodium carbonate (Na₂CO₃) is a very important chemical in many industries and domestic purposes in the world. Due to weak basic characteristics and other specific chemical properties, Sodium carbonate shows variety of reactions. In this tutorial, we will see how Sodium carbonate reacts with other chemicals.

Content

• Solubility of Sodium carbonate (Washing soda / Na₂CO₃) in water
• Sodium carbonate in qualitative analysis
  • Precipitation reactions of Sodium carbonate
  • Sodium carbonate and acid reaction
  • Sodium carbonate and carboxylic acid reaction
  • Sodium carbonate and milk of lime reaction
  • Decomposition of Sodium carbonate
• How sodium carbonate is used to remove hardness of water?
  • Remove temporary hardness of hard water by Sodium carbonate
  • How to separate nitrogen gas from oxygen gas?<

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Solubility of Sodium carbonate (Washing soda / Na₂CO₃) in water

Sodium carbonate is introduced in many names such as washing soda or soda ash. It's is a water soluble and gives a colourless aqueous solution. Dissolved sodium carbonate completely dissolve to Sodium cation and carbonate ions in water as mentioned below.

Na₂CO_3(aq) → Na⁺_(aq) + CO₃^2-_(aq)

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Sodium carbonate in qualitative analysis

Sodium carbonate is used to identify cations in qualitative analysis. It precipitates insoluble carbonates of calcium, barium and strontium and many more cations.

Precipitation reactions of Sodium carbonate

Carbonate ion gives insoluble metal carbonates with most of the metal cations. From metal carbonates, Sodium carbonate, Potassium carbonate, Rubidium carbonate, Cesium are soluble in water and other all carbonate compounds are insoluble in water.

Sodium carbonate and acid reaction

When dilute acid (HCl, H₂SO₄) is added to a solid sodium carbonate (Na₂CO₃) , carbon dioxide gas is generated.

Sodium carbonate and carboxylic acid reaction

Sodium carbonate and carboxylic acids (RCOOH) react to give Carbon dioxide (CO₂) and sodium salt of carboxylic acid (RCOO^-Na⁺) and water. Also sodium bicarbonate reacts with carboxylic acid to give CO₂.

Note : Alcohols and phenol do not react with sodium carbonate and sodium bicarbonate to release carbon dioxide gas. This experiments is used to identify carboxylic acid from alcohols and phenols.

Sodium carbonate and milk of lime reaction

With hot milk of lime (Ca(OH)₂), sodium carbonate react to form sodium hydroxide and calcium carbonate. Calcium carbonate exist as a precipitate.

Decomposition of Na₂CO₃

All carbonates of alkali metals ( Group 1A) are stable to heat. Therefore decomposition of Na₂CO₃ is difficult.

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How sodium carbonate is used to remove hardness of water?

There are two types of hardness of water as temporary hardness and permanent hardness. Na₂CO₃ can be used to remove both temporary hardness and permanent hardness.

Remove temporary hardness of hard water

Bicarbonate ion (HCO₃^-) of Ca²⁺ and Mg²⁺ ions cause to temporary hardness of water. Adding Sodium carbonate to hard water will form Calcium carbonate (CaCO₃) and Magnesium carbonate (MgCO₃) precipitates by replacing HCO₃^- anions.

Remove permanent hardness of hard water

Sulfate ions (SO₄^2-) and Chloride ions (Cl^-) of Ca²⁺ and Mg²⁺ cause to permanent hardness of water. Adding Sodium carbonate will form Calcium carbonate (CaCO₃) and Magnesium carbonate (MgCO₃) precipitates by removing Ca²⁺ and Mg²⁺ from water.

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Questions

Ask your chemistry questions and find the answers

Is sodium carbonate acidic or basic?

sodium carbonate is a basic compound. sodium carbonate dissociates completely in the water to Na⁺ ion CO₃^2- ion. Na⁺ ion is stable in the water. But CO₃^2- is not stable in the water and is hydrolyzed in the water.

carbonate ion hydrolysis

By the hydrolysis of carbonate ion, OH^- ions are released.

Due to release of OH^-, sodium carbonate solution is weak basic.

What is soda ash?

Sodium carbonate is a white crystalline solid which exists as a decahydrate (Na₂CO₃.10H₂O). This is called washing soda. When decahydrate gets heat, it looses the water of crystallization to form monohydrate ( Na₂CO₃.H₂O). Above 373K, the monohydrate becomes completely anhydrous and changes to a white powder called soda ash.

What will happen when calcium chloride aqueous solution is added to sodium carbonate solution?

With addition of calcium chloride (CaCl₂), there are Na⁺, CO₃^2-, Ca²⁺ and Cl^- ions in the water. We know CaCO₃ is a precipitate. Therefore in higher concentrations of Ca²⁺ and CO₃^2- ions in aqueous solution, a white precipitate (CaCO₃) is formed.