Plant oils and their uses

AQA GCSE Science & Additional Science

Chemistry 1 Topic 6

Hodder Education Revision Lessons

Plant oils and their usesPlant oils and

their uses

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Chemistry 1 Topic 6

Overview• Many plants produce useful oils that can be converted into

consumer products including processed foods. • Emulsions can be made and have a number of uses. • Vegetable oils can be hardened to make margarine. • Biodiesel fuel can be produced from vegetable oils.

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Chemistry 1 Topic 6

Plant oils and their uses 1Some fruits, seeds and nuts are rich in oils that can be extracted.

The plant material is crushed and the oil removed by pressing. Alternatively, the oil is dissolved in a solvent such as hexane and then the solvent is distilled off leaving the oil behind.

Water and other impurities are removed.

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What is meant by cold-pressed virgin olive oil?


Chemistry 1 Topic 6

Plant oils and their uses 2

Why isn’t oil extracted from the leaves of plants?

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Plant oil

What part of the plant

does the oil come from?

Olive oil Fruit

Rape oil Seeds

Peanut oil Nut (food store for seeds)

Avocado oil Fruit

Jojoba oil Seed

Palm oil Fruit


Chemistry 1 Topic 6

Plant oils and their uses 3Vegetable oils are important foods and fuels because they provide a lot of energy. They also provide us with nutrients.

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What nutrients do plant oils contain?


Chemistry 1 Topic 6

Plant oils and their uses 4

Vegetable oils have higher boiling points than water and so can be used to cook foods at higher temperatures than by boiling.

This produces quicker cooking and different flavours, but it increases the energy that the food produces when it is eaten.

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Why are you more likely to put on weight if you eat a lot of chips than if you eat boiled potatoes?


Chemistry 1 Topic 6

Emulsions 1

Oils do not dissolve in water. They can be used to produce emulsions — tiny droplets of oil suspended in water.

Emulsions are thicker than oil or water and have many uses that depend on their special properties.

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What uses do emulsions have?


Chemistry 1 Topic 6

Emulsions 2

Emulsions provide better texture, coating ability and appearance, for example in

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• salad dressings• ice creams• cosmetics• paints

Emulsifiers have hydrophilic and hydrophobic properties.


Chemistry 1 Topic 6

Emulsifiers

Emulsifiers are used to make emulsions stable. They have hydrophilic (water loving) and hydrophobic (water hating) properties.

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Explain how emulsifiers work.


Chemistry 1 Topic 6

Saturated and unsaturated oils 1

Unsaturated vegetable oils contain carbon–carbon double bonds. They are sometimes called polyunsaturated fats.

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Unsaturated fats can be detected by reacting with bromine water. Bromine water turns from orange-brown to colourless when it reacts with unsaturated fats.


Chemistry 1 Topic 6

Saturated and unsaturated oils 2

Unsaturated vegetable oils can be hardened to make them spreadable by reacting them with hydrogen in the presence of a nickel catalyst at about 60°C.

Hydrogen adds to the carbon–carbon double bonds. Hydrogenated oils have higher melting points so they are solids at room temperature, making them useful as spreads and in cakes and pastries.

What hydrogenated oils are there?

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Plant oils and their uses