From baking soda to washing soda
Two small steps turn a kitchen powder into a cleaning crystal.
One more step
You know that heating baking soda leaves sodium carbonate. Washing soda is a crystal form of it.
How could we turn sodium carbonate powder into washing soda crystals?
What this lesson covers
The idea
Washing soda (Na2CO3.10H2O) is a basic salt obtained by recrystallisation of sodium carbonate, which is itself obtained by heating baking soda.
One more step
You know that heating baking soda leaves sodium carbonate. Washing soda is a crystal form of it.
How could we turn sodium carbonate powder into washing soda crystals?
- Dissolve it in water and let crystals form again
- Heat it even more
- Add an acid to it
Make washing soda
Press the buttons in order. Watch what appears.
Heat, then recrystallise
Washing soda is Na₂CO₃·10H₂O, a basic salt. It is obtained by recrystallisation of sodium carbonate, which is itself obtained by heating baking soda.
Uses: glass, soap and paper industries; making sodium compounds such as borax; a cleaning agent at home; removing permanent hardness of water.
- Substance | Formula | How we get it
- Baking soda | NaHCO₃ | made from sodium chloride
- Sodium carbonate | Na₂CO₃ | heat baking soda
- Washing soda | Na₂CO₃·10H₂O | recrystallise sodium carbonate
Notes
Washing soda (Na₂CO₃·10H₂O) is a basic salt obtained by recrystallisation of sodium carbonate, which is itself obtained by heating baking soda.
Check yourself
How is washing soda obtained from sodium carbonate?
Which is the formula of washing soda?
Which order is right?
Which is a use of washing soda?
- By burning it in air. Burning does not make it. The crystals come from recrystallisation.
- By recrystallisation — correct. Yes! Sodium carbonate recrystallised with water gives Na₂CO₃·10H₂O.
- By adding dilute HCl. HCl reacts with sodium carbonate and gives CO₂, NaCl and water.
- NaHCO₃. That is baking soda.
- Na₂CO₃. That is sodium carbonate, without the 10 H₂O.
- Na₂CO₃·10H₂O — correct. Yes! Sodium carbonate with 10 water molecules.
- Baking soda → sodium carbonate → washing soda — correct. Yes! Heat first, then recrystallise.
- Sodium carbonate → baking soda → washing soda. Heating goes from baking soda to sodium carbonate, not the other way round.
- Washing soda → baking soda → sodium carbonate. The chain starts with baking soda.
- Making cakes rise. That is baking powder (baking soda with a weak acid).
- Removing permanent hardness of water — correct. Yes! It is also used in glass, soap and paper industries.
- Putting out a fire as a gas. Baking soda is used in soda-acid fire extinguishers, not washing soda.