Alcohols and carboxylic acids (Section 6)

Question 1

What is the general formula for alcohols?

Answer 1

CnH(2n+1)OH

Question 2

What is the functional group for alcohols?

Answer 2

-OH

Question 3

What do alcohols form when oxidised?

Answer 3

Carboxylic acids

Question 4

Name an oxidising agent that can be used to oxidise an alcohol to form a carboxylic acid

Answer 4

Potassium dichromate(VI) (In dilute sulfuric acid)

Question 5

State the colour change when an alcohol is oxidised

Answer 5

The potassium dichromate (VI) solution will go from orange to green

Question 6

What is formed after ethanol is oxidised?

Answer 6

Ethanoic acid

Question 7

What are the products of complete combustion?

Answer 7

Carbon dioxide and water

Question 8

What are the two ways to produce ethanol?

Answer 8

Fermentation and direct hydration (Ethene and steam)

Question 9

How is ethanol created from direct hydration (Ethene and steam)

Answer 9

.Ethene is produced from the cracking of crude oil
.Ethene (C2H4) will react with steam (H2O)to make ethanol (C2H5OH)
.The reaction needs to happen at 300 degrees C and a pressure of 60-70 atmosphere
.Phosphoric acid is used as a catalyst

Question 10

What is the catalyst used in Direct hydration?

Answer 10

Phosphoric acid

Question 11

What temperature should direct hydration take place at

Answer 11

300 degrees celcius

Question 12

what pressure should direct hydration take place at?

Answer 12

60-70 atmosphere

Question 13

What are the advantages of direct hydration?

Answer 13

.Cheap at the moment
.No waste products
.100% yeald
.Fast

Question 14

What are the disadvantages of direct hydration?

Answer 14

.Crude oil is non renewable which means it will start to run out soon
.Ethene will eventually become expensive

Question 15

How is ethanol created using fermentation?

Answer 15

.Sugar (glucose) is converted into ethanol using yeast
.Yeast cells contain an enzyme which is a biological catalyst
.The mixture needs to be at 30 degrees C
.If it’s too hot the enzymes denature and if it’s too cold the reaction will be too slow
.It is important to ensure the mixture is kept in anaerobic conditions otherwise the the oxygen will convert the ethanol into ethanoic acid

Question 16

What are the advantages of fermentation?

Answer 16

.Yeast is easy to grow
.The raw materials are renewable resources
.Cheap and low energy cost

Question 17

What are the disadvantages of fermentation?

Answer 17

.The ethanol isn’t very concentrated
.Needs to be distilled and purified
.Slow

Question 18

Why does fermentation take place at 30 degrees C?

Answer 18

.30 degrees C is the optimum temperature for the enzymes in yeast cells
.If it’s too hot, they denature
.If it’s too cold, the process would be to slow

Question 19

What are the products of fermentation?

Answer 19

Ethanol and carbon dioxide

Question 20

Why is ethanol purified and distilled after fermentation?

Answer 20

As it isn’t concentrated enough after fermentation

Question 21

What is the functional group of carboxylic acids?

Answer 21

-COOH

Question 22

What is the molecular formula of methanoic acid?

Answer 22

HCOOH

Question 23

Do carboxylic contain double bonds?

Answer 23

Yes, on the carbon to the oxygen

Question 24

What are the products of Ethanoic acid + sodium carbonate?

Answer 24

Sodium ethanoate + water + carbon dioxide

Question 25

What are the products of Ethanoic acid + magnesium?

Answer 25

Magnesium ethanoate + hydrogen

Question 26

How are esters formed?

Answer 26

When an alcohol is reacted with a carboxylic acid with the presence of an acid catalyst

Question 27

How can ethanoic acid be made?

Answer 27

By oxidising ethanol

Question 28

What are the products of ethanol + oxygen?

Answer 28

Ethanoic acid + water

Question 29

How would you make vinegar?

Answer 29

.By oxidising ethanol to make ethanoic acid
.Then you can dissolve the ethanoic acid in water to make vinegar

Question 30

What is vinegar used for?

Answer 30

Flavoring and preserving foods