Hard Water - Chemistry - Unit 3 - AQA

Hardness of Water

Water can be hard or soft, depending on where you live and the rocks water passes through before reaching your house.

Scum

• If you have soft water, when mixed with soap a nice lather forms. However with hard water a nasty scum forms instead (unless soapless detergents are being used).
• Hard water contains dissolved calcium ions and magnesium ions which react with soap to form scum. Scum is insoluble. 
• To get a decent lather more soap has to be used, as it costs money to buy soap, money is being wasted through creating a decent lather in hard water.

Scale

• When …