F322 - Alcohols, Halogenoalkanes and Analysis

Question 0

Why do alcohols have a low volatility?

Answer 0

Hydrogen bonds are formed between the alcohol molecules which are a stronger force of attraction.

Question 1

Why are alcohols water soluble?

Answer 1

Form hydrogen bonds with the water molecules which allow the alcohol molecules to be pulled apart and mix with the water molecules.

Question 2

What is fermentation?

Answer 2

The process of glucose being converted to ethanol and carbon dioxide using yeast as a catalyst.

Question 3

What are the advantages of using fermentation as a method of ethanol production?

Answer 3

Can be done at a lower temperature (yeast is killed off above 47 degrees), and glucose is a renewable resource (can be grown).

Question 4

How is ethanol produced using addition reactions?

Answer 4

Reaction of ethene with steam in the presence of an acid catalyst (usually phosphoric acid).

Question 5

What are the advantages of using addition reactions to make ethanol?

Answer 5

Can be done at high temperature so reaction rate can be quicker, 100% atom economy.

Question 6

What is the most common use of ethanol?

Answer 6

Alcoholic drinks or in methylated spirits/solvent (this cannot be drunk!)

Question 7

What is the most common use of methanol?

Answer 7

Petrol additive to improve combustion or as a feedstock in the production of organic chemicals.

Question 8

What is a primary alcohol?

Answer 8

Where the carbon that the OH group is attached to is attached to one other C.

Question 9

What is a secondary alcohol?

Answer 9

Where the C that the OH group is attached to is attached to two other C’s.

Question 10

What is a tertiary alcohol?

Answer 10

Where the C that the OH group is attached to is attached to 3 other C’s.

Question 11

When primary alcohols are oxidised using acidified potassium dichromate under reflux what type of product is formed? What colour change would be seen?

Answer 11

Carboxylic acid and orange to green

Question 12

When primary alcohols are oxidised using acidified potassium dichromate under distillation what type of product is formed? What colour change would be seen?

Answer 12

Aldehydes and orange to green

Question 13

When secondary alcohols are oxidised using acidified potassium dichromate under reflux what type of product is formed? What colour change would be seen?

Answer 13

Ketones and orange to green

Question 14

When tertiary alcohols are oxidised using acidified potassium dichromate under reflux what type of product is formed? What colour change would be seen?

Answer 14

No reaction, would remain orange

Question 15

What are the reagents required for esterification?

Answer 15

Alcohol, carboxylic acid and an acid catalyst (sulphuric acid usually)

Question 16

What are the reagents needed for the dehydration of an alcohol?

Answer 16

Alcohol and hot pumice/aluminium oxide or concentrated sulphuric acid

Question 17

What type of reaction takes place for the hydrolysis of a halogenoalkane?

Answer 17

(Nucleophilic) substitution

Question 18

What is a nucleophile?

Answer 18

An electron pair donor

Question 19

What is PTFE used for and why?

Answer 19

Non-stick saucepans and waterproof clothing. It is chemically inert, has a high melting point and is smooth and slippery.

Question 20

What are CFC’s used for and why?

Answer 20

Propellants, refrigerants, blowing agents or cleaning solvents because they are inert, non-toxic, and non-flammable.

Question 21

What problems have the use of CFC’s contributed to?

Answer 21

Thinning the ozone layer in the stratosphere.

Question 22

What breaks down CFC’s in the atmosphere?

Answer 22

Ultraviolet radiation

Question 23

What happens when covalent bonds absorb energy?

Answer 23

The bonds vibrate/bend/stretch

Question 24

How do IR spectrometers work?

Answer 24

Analyse the radiation absorbed by different covalent bonds.

Question 25

How do breathalysers work?

Answer 25

IR spectroscopy is used to measure the ethanol content of a driver’s breath.

Question 26

What are the reagents for the hydrolysis of a halogenoalkane?

Answer 26

Halogenoalkane and hot aqueous alkali

Question 27

How do the rates of hydrolysis vary for primary halogenoalkanes down group 7?

Answer 27

Rate of hydrolysis increases down group 7. (Due to weaker C-halide bonds)

Question 28

Which functional group absorption indicates an alcohol?

Answer 28

O-H bond

Question 29

Which functional group absorption indicates a ketone or aldehyde?

Answer 29

C=O bond

Question 30

Which functional group absorption indicates a carboxylic acid?

Answer 30

C=O bond and O-H bond

Question 31

How does a mass spectrometer find the relative atomic mass of an element?

Answer 31

It measures the mass of each different isotope and measures the relative abundance of each isotope. A vaporised sample of the element is injected and the atoms are turned into positive ions by electron bombardment.

Question 32

How is a mass spectrometer used to identify unknown compounds?

Answer 32

Inject a vapourised sample and turn them into slightly charged positive ions with the same molecular mass as the molecules. This gives the molecular ion peak. Electron bombardment can also be used to break apart the molecules to make fragments.