Reactions of alkenes and alcohols (7.2)

Question 1

What are alkenes?

Answer 1

hydrocarbons with a double carbon-carbon bond

Question 2

What is the general formula for the homologous series of alkenes?

Answer 2

C_nH_2n

Question 3

Are alkene molecules saturated or unsaturated?

Answer 3

unsaturated

Question 4

Why are alkene molecules unsaturated?

Answer 4

they have a double bond between the carbon atoms

Question 5

What are the first four members of the homologous series of alkenes?

Answer 5

ethene, propene, butene and pentene

no ‘methene’ as it would not have a double bond due to only having one carbon atom

Question 6

What forms can alkenes be represented in? (formula and diagram) e.g. for propene

Answer 6

Question 7

What is the functional group of alkenes?

Answer 7

C=C

Question 8

What determines the reactions of organic compounds?

Answer 8

the generality of reactions of functional groups

Question 9

How do alkenes react with oxygen in combustion?

Answer 9

Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion

Question 10

What is incomplete combustion caused by?

Answer 10

A lack of oxygen

Question 11

How do alkenes react with hydrogen, oxygen and the halogens?

Answer 11

By the addition of atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond (double bond breaks) forming a saturated molecule

these are called addition reactions

Question 12

What is the functional group of alcohols?

Answer 12

-OH

Question 13

What are the first four members of a homologous series of alcohols?

Answer 13

methanol, ethanol, propanol and butanol

Question 14

What forms can alcohols be represented in?

Answer 14

You can combine the formula if you want. e.g. for ethanol C₂H₅OH

or add another CH₂ every time starting with alcohol (methanol doesn’t;t have this)

Question 15

What is the formula of the homologous series of alcohols?

Answer 15

C_nH_2n+1OH

Question 16

3 needed

What are the uses of alcohols?

Answer 16

• solvents
• fuels
• ethanol is main alcohol in alcoholic drinks

Question 17

What is formed when alcohols burn in air?

Answer 17

carbon dioxide and water

Question 18

What is formed when alcohols react with sodium?

Answer 18

form solution of sodium alkoxide (C₂H₅ONa)

Question 19

What happens when alcohol is added to water?

Answer 19

mix easily to produce a solution (dissolve easily)

as the alcohol molecule gets longer, its solubility decreases

Question 20

How can alcohols be oxidised without combustion?

Answer 20

Through use of an oxidising agent, to produce a carboxylic acid

Question 21

What is the equation for the fermentation of sugar using yeast?

Answer 21

glucose ⇢ ethanol + carbon dioxide

yeast as a catalyst

Question 22

2 needed + 2 minor

What are the conditions are needed for the fermentation of sugar using yeast?

Answer 22

• anaerobic conditions
• warm (temperature, 25-35°C)
• sugars dissolved in water, and mixed with yeast
• an air lock to allow carbon dioxide out, while stopping air getting in

Question 23

What is the functional group of carboxylic acids?

Answer 23

-COOH

Question 24

What are the first four members of a homologous series of carboxylic acids?

Answer 24

methanoic acid, ethanoic acid, propanoic acid and butanoic acid

Question 25

What forms can carboxylic acids be represented in? (formula and diagram)

Answer 25

Question 26

What is the general formula for the homologous series of carboxylic acids?

Answer 26

C_n-1H_2n-1COOH

Question 27

What happens when carboxylic acids react with carbonates?

Answer 27

carbonates gently fizz in solutions carboxylic acids, releasing carbon dioxide gas

Question 28

What happens when carboxylic acids dissolve in water?

Answer 28

they form acidic solutions with pH values less than 7

Question 29

What happens when carboxylic acids react with alcohols?

Answer 29

they form esters

Question 30

What is the word equation for the reaction of ethanoic acid and ethanol?

Answer 30

ethanol + ethanoic acid ⇢ **ethyl ethanoate** + water

Question 31

Why are carboxylic acids weak acids?

Answer 31

Carboxylic acids are weak acids because they only **partially ionise** in solution. Their solutions do not contain many hydrogen ions compared to a solution of a strong acid at the same concentration

Question 32

What are 2 properties of esters?

Answer 32

* volatile * pleasant smell *so used in perfumes*

Question 33

What is the functional group of esters?

Answer 33

Question 34

How are carboxylic acids produced?

Answer 34

The (oxidation) reaction between an alcohol and oxygen **without** combsution, using an oxidising agent

Question 35

The oxidation of alcohols forms which products with and without combustion?

Answer 35

with combustion - carbon dioxide + water without combustion - carboxylic acids

Question 36

Incomplete combustion produces carbon monoxide or carbon particulates, due to a lack of oxygen, what is the problem with these two waste products?

Answer 36

Carbon monoxide - is a toxic gas Carbon particulates - cause global dimming

Question 37

Alkanes can be used as (…)

Answer 37

fuels

Question 38

What is seen when fermentation takes place?

Answer 38

fizzing

Question 39

What gas is produced when sodium reacts with ethanol?

Answer 39

hydrogen gas

Question 40

What is the catalyst in a reaction between ethanol and ethanoic acid?

Answer 40

a strong acid

Question 41

What is the compound added to ethene to produce ethanol?

Answer 41

Water

Question 42

What is a test for carboxylic acids?

Answer 42

Add hydrogen carbonate If carboxylic acid present, the solution will effervesce * as dilute acid - for alcohol + other non-acids, this will not occur* * could also use any metal or other carbonate, but it must be named*

Question 43

What process is used to separate ethanol from water and what physical property allows this to occur?

Answer 43

fractional distillation Both compounds have different boiling points (ethanol has lower boiling point than water)

Question 44

# 3 needed Which substances can be added to alkenes in an addition reaction?

Answer 44

* Halogens * Water * Hydrogen

Question 45

How can different forms of poly(ethene) be produced from ethene?

Answer 45

Use different reaction conditions