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Flashcards in Chapter 14 Deck (45)
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1
Q

What is the functional group of alcohols?

A

-OH, hydroxyl group

2
Q

What is the suffix of alcohols?

A

-ol

3
Q

What is the general formula of alcohols?

A

CnH2n+1OH or R-OH

4
Q

When do positional isomers occur in alcohols?

A

In carbon chains of 3 or more

5
Q

What is a polyhydric alcohol?

A

Alcohols that contain two or more -OH groups

6
Q

What is the structure of phenol?

A

When an -OH group is attached directly to a benzene ring

7
Q

What is an ether?

A

A structural isomer of alcohol

8
Q

Are alcohols polar or non-polar?

A

Polar

9
Q

Where are the partial charges on an alcohol molecule that cause it to be polar?

A
  • Partial positive charge on the Carbon atom the -OH group is attached to.
  • Partial negative charge on the Oxygen in the -OH group.
10
Q

Why does the boiling point increase with chain length in alcohols?

A

Alcohols create hydrogen bonds with each other, so have higher boiling points than alkanes of similar Mr as more energy is needed to overcome the stronger intermolecular forces.

11
Q

Define volatility?

A

A measure of the tendency of a substance to vaporise (the higher the boiling point the lower the volatility)

12
Q

How does the volatility of alcohols compare to alkanes?

A

Alcohols are less volatile than alkanes of similar Mr.

13
Q

What is the solubility of alcohols like?

A

They have -OH groups which can form hydrogen bonds with water. This makes the first three alcohols soluble in water but after that the long alkyl chain interferes with the Hydrogen bonds.

14
Q

When are alcohols soluble in water?

A

The first three alcohols are soluble in water but after that the long alkyl chain interferes with the Hydrogen bonds.

15
Q

What is ethanol and when is it used?

A

Ethanol is ‘alcohol’ in alcoholic drinks. Commonly used as a solvent in the form of methylated spirits.

16
Q

What is methanol and when is it used?

A

Methanol is used as a petrol additive to improve combustion. Important feedstock in the production of organic chemicals.

17
Q

What is ethane-1,2-diol and when is it used?

A

Used as antifreeze as it lowers the melting point of water from 0” to as low as -40” when mixed with water.

18
Q

What are the 4 reactions alcohols can take place in?

A
  1. Combustion
  2. Oxidation
  3. Dehydration
  4. Substitution
19
Q

What is produced in the complete combustion of alcohols?

A

Carbon Dioxide and water

20
Q

Why do alcohols make good fuels?

A

The combustion of alcohols is exothermic

21
Q

What does increasing the number of carbon atoms in the chain during combustion result in?

A

It increases the amount of heat energy released per mole.

22
Q

What does the oxidation of alcohols produce?

A

Molecules with different functional groups

23
Q

What functional group does Aldehydes and Ketones contain?

A

The CARBONYL GROUP

24
Q

What is the Carbonyl Group ?

A

A carbon double bonded to the oxygen. -C=O

25
Q

What is the suffix of an Aldehyde?

A

‘…al’

26
Q

What is the suffix of a Ketone?

A

‘…one’

27
Q

What functional group do Carboxylic acids contain?

A

The CARBOXYL GROUP

28
Q

What is the Carboxyl Group?

A

-COOH

29
Q

What is the suffix of a Carboxylic Acid?

A

‘….oic acid’

30
Q

What is used to carry out the oxidation of alcohols?

A

Acidified potassium dichromate (VI) solution

31
Q

What colour does the potassium dichromate solution change to during a reaction?

A

From orange to green

32
Q

What is the equation for potassium dichromate?

A

Cr2O7 ^2-

33
Q

What is the equation for the potassium dichromate after it turns green?

A

Cr ^3+

34
Q

What are primary alcohols oxidised to?

A

Aldehydes and then to a carboxylic acid

35
Q

How is a primary alcohol oxidised into a aldehyde?

A

Under distillation with H+/ Cr2O7 ^2-

36
Q

How is a aldehyde oxidised into a carboxylic acid?

A

Under reflux with H+/Cr2O7 ^2-

37
Q

How are ketones made?

A

Secondary alcohols are oxidised to ketones, under reflux with H+/Cr2O7 ^2-

38
Q

What are tertiary alcohols oxidised into?

A

They are not oxidised, the reaction mixture stays orange.

39
Q

Define dehydration?

A

A water molecule is removed from a starting reactant

40
Q

Define an elimination reaction

A

A small molecule is removed from a single larger molecule leaving an unsaturated molecule.

41
Q

What acid catalyst is used in the dehydration of alcohols?

A

Concentrated H2SO4/ Concentrated H3PO4

42
Q

How is a dehydration of alcohols reaction carried out?

A

The alcohol is heated under reflux in with an acid catalyst

43
Q

What does the dehydration of an unsymmetrical alcohol result in?

A

2 alkenes that are positional isomers

44
Q

What occurs during the mechanism of the dehydration of alcohols?

A

The hydrogen atom is removed from the carbon atom bonded to the most number of carbon atoms.

45
Q

Define a substitution reaction

A

When an atom/ group of atoms is replaced by another atom/ group of atoms.