Sodium carbonate and bicarbonate reactions | Na₂CO₃ | NaHCO₃

Sodium carbonate and sodium bicarbonate are very important chemical materials and used in many industries in the world.

Washing soda, soda ash, baking soda

• Sodium carbonate (Washing soda, soda ash) - Na₂CO₃
• Sodium bicarbonate (baking soda) - NaHCO₃

Sodium carbonate in qualitative analysis

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

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 CO₂ and 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.

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 hard

Sodium bicarbonate or baking soda, NaHCO₃

Sodium bicarbonate( baking soda, sodium hydrogen carbonate) is obtained as an intermediate product in solvay process for the manufacturing of sodium carbonate.

Preparing sodium bicarbonate in the laboratory

Passing carbon dioxide to a cold concentrated solution of sodium carbonate will give sodium bicarbonate(NaHCO₃).

Properties of sodium bicarbonate

1. Sparingly soluble in water
2. A white crystalline solid
3. When heating(373K), it decomposes into sodium carbonate, carbon dioxide and water.
4. Aqueous solution of sodium bicarbonate is alkaline in nature.

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

HCO₃^- of Ca²⁺ and Mg²⁺ cause to temporary hardness. Adding Na₂CO₃ will form CaCO₃ and MgCO₃ precipitates by removing HCO₃^-.

Remove permanent hardness of hard water

SO₄^2- and Cl^- of Ca²⁺ and Mg²⁺ cause to permanent hardness. Adding Na₂CO₃ will form CaCO₃ and MgCO₃ precipitates by removing Ca²⁺ and Mg²⁺ from water.

Reactions of sodium carbonate preparing

Urea and NaOH reaction

Ammonia and sodium carbonate are given as products by the reaction of urea and NaOH.

Questions and answers of Na₂CO₃ and solvay process

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.

Molecular mass of sodium carbonate

M_Na2CO3 = 23*2 + 12 + 16*3

M_Na2CO3 = 106 g mol^-1

What is the solubility of sodium carbonate ?

Solubility - 30.7 g/100 g water at 25⁰C