Ways to soften

• When temporary hard water is boiled the hardness is removed -> thermal decomposition reaction occurs ( hydrogen carbonate breaks apart when heated)
• Calcium hydrogen carbonate -> Calcium Carbonate + water + Carbon dioxide
• boiled temporary hard water produces insoluble white solid : limescale
• boiling Permenant hard water does not remove hardness as sulfates and nitrates do not break apart at high temps
• permament hard water's hardness can be removed by -> adding sodium carbonate (washing soda ) + ion exchange resins
• adding sodium carbonate to permanent hard water = precipitation reaction -> creates precipitate ( white solid )
• adding sodium carbonate to perm hard water =

  sodium carbonate + calcium sulfate -> calcium carbonate + sodium sulfate
• ion exchange resin removes hardness from temporary + permenant hard water
• In the ion exchange resin Ca ²⁺ / Mg ² are exchanged for Na ⁺ ions that do not cause water hardness
• The ion exchange resin will eventually stop working when it runs out of Na ⁺ -> has to be washed out in Sodium Chloride to put Na ⁺ back in
• boiling advantage = cheap equipment

  disadvantage = only used for small volumes , doesn't remove permanent hardness and limescale ( calcium carbonate ) is formed.
• Adding sodium carbonate advantage = removes both temporary + permanent hard water hardness

  disadvantage = Limescale ( Carbon carbonate ) is formed which can block washing machine pipes
• Ion exchange resin ad = removes both temporary and permanent water hardness and is a continuous process.

  concentrated sodium -> cheap + widely available

  dis = Exchange columns are expensive, the resin needs to be regenerated regularly and the soft water contains sodium ions which could lead to heart problems
• Soap can remove both types of water hardness
• distilled water does not contain any ions -> soft water