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H. H. H-C-C-O. H. H. H. Making Ethanol. Making Ethanol. Ethanol is the chemical name for alcohol. A molecule of ethanol looks like this. It can be used as a fuel. There are two ways of making ethanol. 1. From Crude oil. Add water (steam). Crude oil. Fractional Distillation.
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H H H-C-C-O H H H Making Ethanol Making Ethanol Ethanol is the chemical name for alcohol. A molecule of ethanol looks like this. It can be used as a fuel. There are two ways of making ethanol. 1. From Crude oil Add water (steam) Crude oil Fractional Distillation Cracking Ethene Ethanol and a catalyst Add water (steam) Ethene + Water Ethanol and a catalyst
Making Ethanol 1. From Sugar If sugar is dissolved in warm water and yeast added a reaction called fermentation takes place. The yeast converts the sugar into ethanol. This is what is called a batch process (make a bit, empty out, restart with new ingredients) Fermentation: Sugar Ethanol + Carbon Dioxide C6H12O6 2 C2H5OH + 2CO2
Why is ethanol so useful? • Ethanol can be used as a replacement for petrol and other fuels, as a solvent (used in oil based paint), to make perfume. • Why should we use ethanol instead of petrol?
Summary questions Ethanol can be made by two processes, ethene reacting with.........., under pressure and in the presence of a ........., or the fermentation of ............. using enzymes in ................ • 1. Write a word equation to show the production of ethanol from: • Ethene • Glucose • 2. Why is the continuous process better than a batch process for making a product in industry? • 3. How can people claim that the fermentation of plant materials does not contribute to the increase in carbon dioxide in the air? (H)
Make a list • List as many oily foods as you can think of. Where does the oil come from? • e.g. • crisps – sunflower seeds • chocolate spread – nuts • olive oil – olives C1b Oils and the atmosphere
Why do we use oils to cook? • What happens when we cook food in oil? • How does the food change? • Why do we cook with vegetable oil and not water? • Vegetable oil has a higher boiling point so will cook food quicker and change the taste. C1b Oils and the atmosphere
Which food will be healthier? • How and why did you make your decision? Boiled food Grilled food Fried food C1b Oils and the atmosphere
Can you think how they might extract oils? C1b Oils and the atmosphere
Steam Distillation • Some plants quickly release oil when they are crushed, e.g. nuts and seeds. Other oils are more difficult to extract and steam distillation needs to be used. C1b Oils and the atmosphere
Definition of key words • Fats are an important part of the human diet. In the media we often hear terms like ‘saturated, unsaturated, polyunsaturated fats’. These terms have a scientific meaning. • Saturated • Unsaturated • Polyunsaturated What can we use to detect saturated or unsaturated fats? C1b Oils and the atmosphere
Definition of key words • Fats are an important part of the human diet. In the media we often hear terms like ‘saturated, unsaturated, polyunsaturated fats’. These terms have a scientific meaning. • Saturated • Unsaturated • Polyunsaturated • Saturated – no double bonds, • Unsaturated – contains double bonds, • Polyunsaturated – contains many double bonds What can we use to detect saturated or unsaturated fats? Bromine Water C1b Oils and the atmosphere
Match the following key words with their definitions Key word Definition Many double bonds No double bond Contains a double bond • Saturated • Unsaturated • Polyunsaturated
Hardening / Hydrogenation of vegetable oils • During hydrogenation, vegetable oils are hardened by reacting them with hydrogen gasat about 60°C. A nickel catalyst is used to speed up the reaction. • The double bonds are converted to single bonds by the hydrogenation. In this way unsaturated fats can be made into saturated fats. • Saturated vegetable oils are solid at room temperature, and have a higher melting point than unsaturated oils. This makes them suitable for making: • margarine, spreads and pastes or for commercial use in the making of cakes and pastry.
Saturated oils tend to be solid at room temperature, and are sometimes called vegetable fats instead of oils. Unsaturated oils have double bonds between some of their carbon atoms. Unsaturated oils tend to be liquid at room temperature, and are useful for frying food. They can be divided into two categories: Monounsaturated fats have one double bond in each fatty acid Polyunsaturated fats have many double bonds. Why are vegetable oils important foods? What are the health risks of too much oil?
Vegetable oils in fuels Vegetable oils are also used as fuels for vehicles. Some of this biodiesel is made from waste cooking oil and rapeseed oil. Such fuels are carbon neutral, which means that they release only as much carbon dioxide when they burn as was used to make the original oil by photosynthesis. This helps to reduce the threat of global warming. However, some people are concerned about whether it is ethical to use food crops in this way. Why might they have concerns?
Immiscible liquids • An immiscible liquid is a liquid where the two solutions have not mixed properly. Eg oil and water • The oil and water form layers • Is there a way of getting the two liquids to mix?
Emulsifiers • An emulsifier is a substance that causes immiscible liquids to mix • Detergents are emulsifiers. They help when washing up as they allow the fat and water to mix. • Other examples of emulsifiers are: Cayenne pepper, eggs yolk, mustard
Emulsifiers An emulsifier bonds with both liquids. Helping them to mix.
To finish off… • Oil slicks cause massive amounts of damage to the environment. • How could a detergent help to clean up an oil slick?
Key words • One of the following key words does not have a definition. Find the odd one out and then write your own definition for it
Improves the appearance of the foods • Helps food to stay fresh longer • Helps to stop food reacting with Oxygen • Helps to improve the texture of food • Helps to control the PH of foods • Sweet, Sour, Bitter, Savoury, Salt • ACIDITY • ANTIOXIDANTS • COLOURS • EMULSIFIERS/ THICKENERS • E-NUMBERS • FLAVOURINGS • PRESERVATIVES
What are additives? • We use them to make food last longer. • E.g. you can go to the supermarket and by tomato soup that lasts for 12 months. If you had a tomato it wouldn’t last 12 months so additives are put in to preserve the food for longer • We used to use things like vinegar and salt but science has moved on and we have things that can make our food last longer, look better and taste better….ADDITIVES
Some additives are Natural • People are becoming very concerned about food additives, but do not realise that many of them are naturally occurring chemicals such as pectin (E440), which is found in fruit.
Homework • Evaluate the use of vegetable oils and ethanol as fuels. • Decide on any environmental, economic and social issues related to using these fuels sources. • Conclude should we use them as alternative fuels? Why?
