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Science

Detergents

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Detergents such as washing powder are mixtures of substances including active detergent, water softener and enzymes. A 'solvent' is the liquid in which a substance dissolves. Water is an important solvent - other examples are acetone, turpentine and ethanol.

Washing powder/liquid

Modern washing powders and liquids are mixtures of substances. Each ingredient has a particular purpose.

Ingredients of washing powder and their purpose

IngredientPurpose
Active detergentCleaning
Water softenerSoftening hard water
BleachesRemoving coloured stains
Optical brightenersGiving a 'whiter than white' appearance
EnzymesRemoving food stains

Most dirt is best removed by detergent and very hot water. However, there are some advantages of washing at low temperatures:

  • enzymes are denatured at high temperatures
  • some types of clothes are damaged by high temperatures
  • lower temperatures require less energy so the wash is cheaper

The correct washing conditions can be found on the wash label on the item.

Washing-up liquids

Like washing powders, washing-up liquids contain an active detergent and a water softener. They also contain water so that the liquid is thin enough to be dispensed from the bottle, colour and fragrance to make it attractive and a rinsing agent to help water to drain off the crockery.

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