AQA Chemistry (2013) Unit 3
- Created by: Lex
- Created on: 15-05-13 13:05
3.2.1 Hard Water
· Soft water forms a thick lather easily
· Hard water is harder to form a lather
· Dissolved compounds react with soap to form scum
o Sodium stearate (soap) + Ca2+ = calcium stearate (scum) + Na+ ions
· Dissolved calcium and magnesium ions
· Limestone causes hardness
o CO2 dissolved in water – acidic
o CaCO3 (s) + H2O (l) + CO2 (aq) = Ca2+ (aq) + 2HCO3- (aq)
o Ca2+ causes hardness
· Hard water leads to limescale
o Happens in kettles
o Scale is a poor conductor of energy
o Costs more to heat the kettle
· Advantages
o Calcium helps development of bones and teeth
o Hard water helps reduce heart disease
3.2.2 Removing Hardness
· Remove calcium and magnesium ions
· Temporary hardness
o …
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