WM.1

Question 1

Why are alcohols liquids at room temperature?

Answer 1

There are strong intermolecular forces between molecules due to hydrogen bonding.

Question 2

What make alcohols polar molecules?

Answer 2

The O-H bonds.

Question 3

Why do alcohol molecules and water molecules mix well?

Answer 3

They both have strong hydrogen bonding.

Question 4

What is the trend of alcohols and their solubility in water as the chains get longer?

Answer 4

The longer the alcohol molecule, the less soluble it is in water. The properties of higher alcohols gets more like those of corresponding alkane.

Question 5

Why does solubility of alcohols in water decrease as the chain gets longer?

Answer 5

As the hydrocarbon chain get longer and the molecule gets larger, the effect of the OH group on the properties of the molecule becomes less important.

Question 6

What are the three types of alcohol?

Answer 6

Primary alcohols, secondary alcohols, tertiary alcohols.

Question 7

When is an alcohol a primary alcohol?

Answer 7

When the carbon that the OH group is attached to has two hydrogens bonded to it. Or is bonded to one carbon atom.

Question 8

When is an alcohol a secondary alcohol?

Answer 8

When the carbon that the OH group is attached to has one hydrogen bonded to it. Or is bonded to two carbon atoms.

Question 9

When is an alcohol a tertiary alcohol?

Answer 9

When the carbon that the OH group is attached to has no hydrogen bonded to it. Or is bonded to three carbon atoms.

Question 10

What does a alcohol have to have to be able be oxidised?

Answer 10

At least one hydrogen attached to the carbon that the OH group is on. This means only primary and secondary alcohols can be oxidised.

Question 11

What is a oxidising agent we use to oxidise alcohols?

Answer 11

Acidified potassium dichromate. K2Cr2O7.

Question 12

What colour is the dichromate(VI) ion?

Answer 12

Orange.

Question 13

What colour is the chromate(III) ion?

Answer 13

Green.

Question 14

What does the OH group turn into when oxidised?

Answer 14

C=O, a carbonyl group.

Question 15

What type of compound will a primary alcohol be initially oxidised to?

Answer 15

An aldehyde. It has a carbonyl group at the end of a hydrocarbon chain.

Question 16

What type of compound can an aldehyde be further oxidised to?

Answer 16

Carboxylic acid, it has a COOH functional group at the end of a hydrocarbon chain.

Question 17

What type of compound will a secondary alcohol be oxidised to?

Answer 17

A ketone, where the carbonyl group in is between two other carbons in a hydrocarbon chain.

Question 18

Can a ketone be further oxidised?

Answer 18

No, because it doesn’t have a hydrogen attached to the carbon of the carbonyl group and strong C-C bond will need to be broken.

Question 19

What is heat under reflux?

Answer 19

It is a safe method for heating reactions involving volatile and flammable liquids. The liquid is boiled with a vertically mounted condenser so the vapour condenses and returns back into the reaction mixture.

Question 20

How can an alcohol be “directly” oxidised to a carboxylic acid?

Answer 20

Oxidising it with an acidified oxidising agent and heat under reflux.

Question 21

How are aldehydes named?

Answer 21

Suffix - al. E.g. ethanal.

Question 22

How are ketones named?

Answer 22

Suffix - one. E.g propanone.

Question 23

What does dehydration of an alcohol mean?

Answer 23

It means that an alcohol can lose a molecule of water to form an alkene.

Question 24

What condition does industrial dehydration of alcohol require?

Answer 24

A hot catalyst of Al2O3 at 300 degrees celcius.

Question 25

What conditions are required for dehydration of alcohol in a lab?

Answer 25

Conc sulfuric acid with heat under reflux.

Question 26

What type of reaction is dehydration an example of?

Answer 26

Elimination reaction.

Question 27

What is esterification?

Answer 27

It is the reaction where an alcohol reacts with a carboxylic acid to form an ester.

Question 28

What is the gerenal formula of an ester?

Answer 28

RCOOR’, where R is a carbon chain or H, and R’ is a carbon chain.

Question 29

What are four examples of types of compounds that contain a carbonyl group?

Answer 29

Ester, carboxylic acid, ketone, aldehyde.

Question 30

What type of reaction is esterification an example of?

Answer 30

Condensation reaction, where a small molecule is removed.

Question 31

What types of alcohol can esters be made from?

Answer 31

All types of alcohol.

Question 32

What conditions are used for esterification?

Answer 32

Heat under reflux, with presence of an acid catalyst.

Question 33

Why does ester have to be separated out of the reaction mixture?

Answer 33

Because esterification is a reversible reaction and comes to an equilibrium after a while where both reactants and products would be present.

Question 34

How are esters named?

Answer 34

First half refers to the reactant alcohol, and second half refers to the reactant acid, and with -oate at the end.

Question 35

What can we use in esterification instead of the carboxylic acid?

Answer 35

Acid anhydride, which are derivatives of carboxylic acid made by joining two carboxylic molecules eliminating a water molecule. It is more reactive than carboxylic acid.

Question 36

What is different about the esterification using carboxylic acid and acid anhydride?

Answer 36

Esterification with carboxylic acid is reversible but with acid anhydride it’s not meaning yield of ester would be higher.

Question 37

What are ethers?

Answer 37

They are stuctural isomers of alcohols with a C-O-C group.

Question 38

How are ethers named?

Answer 38

Shorter half suffix - oxy and then the longer half.

Question 39

What is an elimination reaction?

Answer 39

A reaction where a small molecule is removed from a large molecule leaving an unsaturated molecule.