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Vegetable oils are often used in salad dressings.

Chemistry - Vegetable Oils and Their Uses

This Chemistry quiz is called 'Chemistry - Vegetable Oils and Their Uses' and it has been written by teachers to help you if you are studying the subject at high school. Playing educational quizzes is a user-friendly way to learn if you are in the 9th or 10th grade - aged 14 to 16.

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In high school, Science students will look at crude oil and other fuels but they will also look at plant oils. This quiz is all about vegetable oils and their different uses, such as food, fuel and other products.

1 .

Unsaturated oils usually take what form at room temperature?

Unsaturated oils are solids at room temperature

Unsaturated oils are liquids at room temperature

Unsaturated oils are gasses at room temperature

Unsaturated oils are emulsions at room temperature

Saturated oils tend to be more solid than equivalent unsaturated oils, which are usually liquids at room temperature

2 .

Why is eating a diet mainly of food cooked in vegetable oils unhealthy?

The oils contain impurities

You can only cook foods that are already high in calories in oils

The high temperatures used for cooking destroy any nutrients in the food

The extra calories can make you overweight

Vegetable oils are high in calories so it is easy to put on weight if you don't exercise a lot more

3 .

What chemical is needed to turn vegetable oil into margarine?

Hydrogen

Sulfur

Carbon

Oxygen

The process is called hydrogenation and is carried out at a high temperature (600^oC) using a catalyst (nickel)

4 .

Which parts of a plant are usually used as the source of vegetable oils?

Leaves only

Flowers and stems

Fruits, seeds and nuts

Roots

Oils can be extracted from flowers but these yield much smaller amounts and often more aromatic oils

5 .

Why does food cook faster in vegetable oils than in boiling water?

The water gets into the food, slowing down the cooking

Oil is a chemical and chemicals cook things faster than just water can

They have higher boiling points than water

Vegetable oils act as catalysts

Kinetic theory meets cooking! Cooking is simply a way of making chemical changes in food to alter taste and texture. Chemical reactions go faster at higher temperatures

6 .

What is an emulsion?

A type of paint

A mixture of oil and water

Something that is used for moisturizing the skin

Something that is only used in cooking

When an oil and water are mixed together, tiny droplets of one liquid spread through the other. In time, an emulsion will separate - the water and oil do not mix permanently and end up as layers

7 .

What are the two methods of extracting vegetable oils?

Distillation and pressing

Filtration and pressing

Distillation and filtration

Centrifuging and pressing

Pressing is usually used to extract the more 'traditional' oils like olive oil

8 .

Why do foods cooked in vegetable oils usually contain more energy than foods cooked by other methods?

They have been subjected to higher temperatures and food holds on to the extra energy

Some of the oil remains on and in the food

They pick up energy from the other foods they are cooked with more easily in the oil

They don't cool off as quickly

During cooking using vegetable oils, some of the oil replaces water in the cells of the food as well as remaining on the surface. Water has zero food energy value but cooking oils have high energy contents

9 .

An emulsifier must be added to make an emulsion (such as paint, skin cream or mayonnaise) stable. Which of the following are the characteristics of a good emulsifier?

Does not form chemical bonds with oils, fats or water

Forms chemical bonds with oils and fats only

Forms chemical bonds with water only

Forms chemical bonds with oils and fats and water

The molecules that make good emulsifiers have one end that bonds with water (hydrophilic) and the other end bonds with oils and fats (hydrophobic). Lecithin is a natural emulsifier commonly used in foods

10 .

Oils and fats can be termed saturated or unsaturated. Unsaturated means what?

All of the water has been removed dusring processing

They won't mix with water

There are no carbon to carbon double bonds in the molecule

There is at least one carbon to carbon double bond in the molecule

As with the alkenes, unsaturated oils and fats will decolourise bromine water

Author: Kev Woodward