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gcse science C4 - E
specific for ocr gateway additonal science B.
| Question | Answer |
|---|---|
| how is a detergent made? | neutralising an organic acid with an alkali |
| remember the equation for neutralisation? | acid + alkali - salt + waterq |
| what part of the neutralisation equation is the detergent? | salt |
| what does perfume do in washing powder? | makes clothes smell nice |
| what does the detergent do in washing powder? | lifts dirt of clothes |
| what do the enzymes do in washing powder? | remove food stains, but only work at low temperatures |
| what do water softeners do in washing powder? | softens hard water |
| what does the optical brightener do is washing powder? | sticks to clothes and makes them really white |
| what does bleach do in washing powder? | removes coloured stains |
| advantages of washing clothes at low temperatures? | -good for the environment -less energy needed -less greenhouse gases -reduced chance of colours running |
| what does hydrophilic mean? | doesn't like water. this end sticks to the grease |
| what does hydrophobic mean? | likes water. this end joins to the water and pulls the grease off the fabric/dish |
| why is dry-cleaning used? | some clothes are damaged if washed in water |
| what is used instead of water in dry-cleaning? | organic solvent |
| why does dry-cleaning remove grease stains better than water? | grease stains don't dissolve in water but they do in the dry-cleaning solvent |
| what makes dry-cleaning better at removing grease stains than water? | dry-cleaning solvent and grease have weak intermolecular forces, meaning they join easily. |
| what makes water not as good at removing grease stains than dry-cleaning? | water have stronger intermolecular forces, called hydrogen bonds. this means that they can't stick to the grease as they are stuck to each other too strongly. |