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27 Cards in this Set
- Front
- Back
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What is a homologous series? |
A series of compounds which:a have the same g eneral formula )show a gradual variation in physical properties asexemplifiedby their boiling points )have similar chemical properties |
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Fermentation to produce ethanol |
Yeast (the enzyme) is added to glucose in anaerobic conditions at around 30-40 degrees c.This produces ethanol and CO2. |
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Why isn't fermented ethanol very concentrated? |
At 10-20% concentration, the reaction stops because the alcohol kills the yeast. |
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How can you make it more concentrated? |
You can use fractional distillation as ethanol has a lower boiling point than water, so it evaporates and can then be cooled. |
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Positives of making ethanol through fermentation |
Can be made anywhere Cheap Renewable resources Simple process-not much energy Mass production |
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Negatives of making ethanol through fermentation |
Not very concentrated Slow process Batch process Impure Uses up land |
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What happens if oxygen enters the process? |
The ethene will turn into ethanoic acid (vinegar). |
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Uses of vinegar |
Flavourings Preserative |
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How is ethanol produced with steam? |
Steam is reacted with ethene to make ethanol. |
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Advantages of producing ethanol with steam |
Continuous process Fast rate of reaction Pure ethanol |
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Disadvantages of producing ethanol with steam |
Non-renewable ethene Complicated process Danger from high pressures and temperatures Needs lots of energy |
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How can ethene be formed from ethanol? |
Ethanol is dehydrated to create ethene and water. A hot aluminium oxide catalyst is used. |
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How do you make an ester? |
Alcohol+carboxylic acid--->ester+water Using an acid catalyst |
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Uses of esters |
Colours and flavourings Polyesters Plastics |
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Polyesters |
They can be turned into plastic bottles or they can be recycled and turned into fleece for clothing. |
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What are two types of esters? |
Oils Fats |
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How are soaps made? |
Oils and fats (esters) are reacted with an alkali and they break down into glycerol and long chain carboxylic acids. The carboxylic acid reacts with the alkali to form a salt and water.The salt is soap. |
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What are soaps |
Sodium or potassium salts of long chain carboxylic acids. |
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What are the two parts of soap? |
Hydrophilic head- dissolves in water Hydrophobic tail- dissolves in grease/dirt |
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How is margarine made? |
Polyunsaturated vegetable oils are hydrogenated.Some of the margarine is saturated and some is unsaturated. |
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What happens in catalytic hydrogenation? |
The double bond in an unsaturated oil is broken and hydrogen is added to form a solid saturated oil. A nickel catalyst is used and at the end, it's filtered out and the liquid is cooled to become solid. |
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What is formed when carboxylic acid reacts with a metal? |
H2 + ethanoate salt |
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What is formed when carboxylic acid reacts with a base?
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H2O + ethanoate salt |
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What is formed when carboxylic acid reacts with a carbonate?
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H20 + CO2 + ethanoate salt |
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What is ethene used for? |
Plastics Polymers |
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Test for a carboxylic acid |
It turns damp blue litmus paper red |
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Properties of esters |
Good solvents (nail varnish remover) Soluble in organic compounds Can be liquids or solids Strong odours Solubility in water decreases as chains get longer |
