Catalytic Hydrogenation and The Steam Method

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How can ethanol be produced with steam?
Ethene reacts with steam to form ethanol.
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What are the pros of this method over fermentation?
It is a cheap process because ethene is cheap and not much is wasted in the steam method. The reaction takes place in a large chemical plant and happens continuously and quickly.
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What is the downside to the steam method?
Ethene is obtained from cracking crude oil fractions and crude oil is non-renewable. This means that this process will become very expensive.
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How can the steam method be conducted in reverse?
Ethanol vapour can be passed over a hot aluminium oxide catalyst which produces ethene and steam.
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What happens when wine or beer bottles are left open?
The ethanol is oxidised to become ethanoic acid, which is the acid within vinegar.
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How is this reaction used for the better?
This reaction is used in the production of vinegar which is used to flavour and preserve foods.
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How do carboxylic acids react?
They react with metals, bases and carbonates like any other acids do. The salts formed from the reaction of ethanoic acid are called ethanoates.
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How are esters formed?
They are formed when an alcohol reacts with a carboxylic acid. Sulfuric acid is also used as a catalyst.
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What is the word equation for the formation of an ester?
alcohol + carboxylic acid --> ester + water
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How are esters used?
They are often used in flavourings and perfumes as they often have sweet and fruity smells. They are often used as polyester fibres and plastic bottles
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What happens when an ester reacts with an alkali?
When an ester reacts with an alkali, soap is formed.
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What are fats and oils?
They are types of esters. They can be boiled up with an alkali solution to make soap.
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What happens in this reaction?
The oil or fat breaks down into glycerol and long chain carboxylic acids which then go on to react with the alkali.
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What happens to soap in water?
Soap forms anions in water, which have a hydrophilic and a hydrophobic part.
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What is the hydrophobic part?
It doesn't like water but is attracted to grease. It is normally a long hydrocarbon chain.
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What is the hydrophilic part?
This means that is dissolves in water and this part of the molecule is normally small and ionic.
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How does soap remove grease?
Soap anions let water and oil mix. The anions surround the oil and forms droplets which lift the dirt away from the fabric.
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What is catalytic hydrogenation?
Unsaturated oils are less viscous than saturated oils. Unsaturated oils can be changed to solid, saturated oils by breaking the double bonds and adding hydrogen, with the help of a nickel catalyst = catalytic hydrogenation.
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What happens to the nickel?
The nickel is a solid and can be filtered out and used again.
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What happens to the unsaturated oil after it has undergone hydrogenation?
It cools to become a solid fat.
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How is this used industrially?
Unsaturated vegetable oils are hydrogenated to make margarine.
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Other cards in this set

Card 2

Front

What are the pros of this method over fermentation?

Back

It is a cheap process because ethene is cheap and not much is wasted in the steam method. The reaction takes place in a large chemical plant and happens continuously and quickly.

Card 3

Front

What is the downside to the steam method?

Back

Preview of the front of card 3

Card 4

Front

How can the steam method be conducted in reverse?

Back

Preview of the front of card 4

Card 5

Front

What happens when wine or beer bottles are left open?

Back

Preview of the front of card 5
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