Removing Hardness From Hard Water

Use washing soda. (sodium carbonate)

• This precipitates out the hardness as insoluble carbonates.

Ca^2+(aq) + CO3^2-(aq) = CaCO3(s)2

Use an ion exchange column.

• These columns contain sodium ions that are exchanged for calcuim and magnesium ions when they pass through them.
  • Once all of the sodium ions are exchanges, the resin is washed with salt solution to give it more sodium ions.