Chemistry: High School: 9th and 10th Grade Quiz - Chemistry - Vegetable Oils and Their Uses (Questions)

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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.

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Many plants produce useful oils that have many uses. They can be converted into various things including processed foods like margarine, fuels like biodiesel, cosmetics and cleaning products. The oils themselves are frequently used in emulsions like salad dressings. But one of the main uses of vegetable oils is in cooking. They have much higher boiling points than water and so can be used to cook foods at higher temperatures than by boiling. Food can therefore be cooked faster than it would have been by cooking in water and different flavors are developed. The drawback to this is that it increases the energy that the food releases when it is eaten so eating too many foods that have been fried or deep fried can have negative consequences for your health.

One of the ways in which your knowledge of vegetable oils could be tested is that you are asked to evaluate given data about an oil that you have probably never heard of. In such cases, keep calm and think about what you do know, then look how it can be applied to the questions. For example, that type of question could test your knowledge of the economic, ethical and environmental issues surrounding the use of vegetable oils as fuels or why certain fats and oils are used in cakes and pastries!

Some, but not all, fruits, seeds and nuts are rich in oils that can be extracted. To obtain the pure plant oil, the fruit, seeds or nuts are crushed and the oil is removed by pressing. In some cases, it is obtained by distillation, for example corn oils and soyabean oils. The seeds are crushed and the oil is extracted by using a solvent to dissolve it from the mixture. The solvent/oil mixture is then distilled to obtain the oil. Water and other impurities are removed during processing.

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1. What are the two methods of extracting vegetable oils?
[ ] Distillation and pressing
[ ] Filtration and pressing
[ ] Distillation and filtration
[ ] Centrifuging and pressing
2. Which parts of a plant are usually used as the source of vegetable oils?
[ ] Leaves only
[ ] Flowers and stems
[ ] Fruits, seeds and nuts
[ ] Roots
3. 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
4. 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
5. 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
6. What chemical is needed to turn vegetable oil into margarine?
[ ] Hydrogen
[ ] Sulfur
[ ] Carbon
[ ] Oxygen
7. 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
8. 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
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
10. 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
Chemistry: High School: 9th and 10th Grade Quiz - Chemistry - Vegetable Oils and Their Uses (Answers)
1. What are the two methods of extracting vegetable oils?
[x] 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
2. Which parts of a plant are usually used as the source of vegetable oils?
[ ] Leaves only
[ ] Flowers and stems
[x] Fruits, seeds and nuts
[ ] Roots
Oils can be extracted from flowers but these yield much smaller amounts and often more aromatic oils
3. 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
[x] 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
4. 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
[x] 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
5. 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
[x] 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
6. What chemical is needed to turn vegetable oil into margarine?
[x] Hydrogen
[ ] Sulfur
[ ] Carbon
[ ] Oxygen
The process is called hydrogenation and is carried out at a high temperature (600oC) using a catalyst (nickel)
7. 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
[x] 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
8. What is an emulsion?
[ ] A type of paint
[x] 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
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
[x] 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. Unsaturated oils usually take what form at room temperature?
[ ] Unsaturated oils are solids at room temperature
[x] 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