Chemistry in your cupboard

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Finish: Introduction; How does a dishwasher work? (1 of 2); How does a dishwasher work? (2 of 2); Softening the water; What does a dishwasher cleaning agent contain?; Surfactants or detergents
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(2 of 2); Alkalis; Bleaches (1 of 2); Bleaches (2 of 2); Biosubstances; Builders; Rinse aid; Recent developments; Different formulations
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Bleaches (2 of 2)

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Activators are added to help the bleaches work. These are essentially, and act similarly to, catalysts. They speed up the reaction so that it can take place effectively at lower temperatures than without the activator. However, activators are consumed stoichiometrically whilst catalysts are not.

The use of activators makes the bleaches more compatible with the enzymes in the dishwasher formulation.

Figure 16 show bleach activity and enzyme activity at different stages of the wash cycle.

Figure 16: Enzyme activity (blue) and bleach activity (red) at different stages of the wash cycle

Activity

Question 5

Explain the phrase ‘This makes the bleaches more compatible with the enzymes.’

Answer 5

Enzymes have their optimum temperature at around 50 °C. Above this temperature the proteins from which they are made denature. The bleaching reaction, on the other hand, will continue to work faster as the temperature increases and so, ideally, a higher temperature than 50 °C would be better.