Washing soda in Class 10 science is sodium carbonate decahydrate , with the chemical formula Na2CO3⋅10H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}Na2​CO3​⋅10H2​O.

Quick definition (Class 10 level)

  • Washing soda is hydrated sodium carbonate that contains 10 molecules of water of crystallisation, so it is called sodium carbonate decahydrate.
  • It is a white, crystalline solid and is commonly used as a cleaning agent and water softener in homes.

Key points you should remember

  • Chemical name: Sodium carbonate decahydrate.
  • Formula: Na2CO3⋅10H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}Na2​CO3​⋅10H2​O.
  • Nature: Basic salt, its solution turns red litmus paper blue.
  • Appearance: White/transparent crystalline solid, soluble in water.
  • Why called washing soda: It removes dirt and grease from clothes and softens hard water, so it is widely used in washing and detergents.

One-line exam-ready answer

Washing soda is sodium carbonate decahydrate, Na2CO3⋅10H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}Na2​CO3​⋅10H2​O, a white crystalline basic salt used as a cleaning agent and water softener.

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