Organic chemistry

Question 1

What are hydrocarbons?

Answer 1

Molecules that only contain hydrogen and carbon

Question 2

What are alkanes called?

Answer 2

A homologous series

Question 3

What are the first 4 alkanes going from smallest to biggest?

Answer 3

Methane (1 carbon), ethane (2 carbons), propane (3 carbons), butane (4 carbons)

Question 4

What’s the general formula for alkanes?

Answer 4

CnH2n+2

Question 5

Are alkanes saturated or unsaturated and what does this mean?

Answer 5

Saturated, meaning they only contain single bonds

Question 6

What is crude oil?

Answer 6

A mixture of hydrocarbons

Question 7

How is crude oil formed?

Answer 7

From the remains of dead plants and animals that died millions of years ago and over time with high temperature and pressure have turned into crude oil

Question 8

What are the properties of short chain hydrocarbons?

Answer 8

Lower boiling points, volatile, runny, flammable

Question 9

What are the properties of long chain hydrocarbons?

Answer 9

Higher boiling points, not volatile, viscous, not flammable

Question 10

What separates crude oil and how does it work?

Answer 10

Fractional distillation - separates the oil into fractions based on their boiling points that have similar numbers of carbon atoms in them

The crude oil is heated and evaporates into a vapour that condenses at different temperatures because of their different boiling points (the fractionation column is cooler at the top and hotter at the bottom)

Question 11

What is the word equation for burning hydrocarbons?

Answer 11

Methane + oxygen –> carbon dioxide + water
CH4 + 2O2 –> CO2 + 2H2O

Question 12

What is the equation for incomplete combustion?

Answer 12

CH4 + 1½O2 –> CO + 2H2O

Question 13

What do you use to test for carbon dioxide?

Answer 13

Lime water - it will change from clear to cloudy

Question 14

What do you use to test for water?

Answer 14

Cobalt chloride paper - it will change from blue to pink

Question 15

What is cracking?

Answer 15

The process of breaking down long chain hydrocarbons into short chain hydrocarbons

Question 16

What are the two types of cracking and how do they work?

Answer 16

Catalytic cracking - the hydrocarbons are heated at a high temperature to vaporise them and then passed over a hot catalyst

Steam cracking - the hydrocarbons are heated at a high temperatures to vaporise and then mixed with steam at a high temperature

Question 17

What is the functional group for alkenes?

Answer 17

C=C

Question 18

Are alkenes saturated or unsaturated and what does this mean?

Answer 18

Unsaturated, meaning they contain at least one carbon double bond

Question 19

What is the general formula for alkenes?

Answer 19

CnH2n

Question 20

What are the first four alkenes going from smallest to biggest?

Answer 20

Ethene (2 carbons), propene (3 carbons), butene (4 carbons), pentene (5 carbons)

Question 21

What is the functional group of alcohol?

Answer 21

OH

Question 22

What two methods are used to produce alcohol and how do they work?

Answer 22

Hydration of ethene - ethene from crude oil is reacted with steam to produce ethanol (the process is pure and fast)

Fermentation of sugars - yeast is added to a source of sugar which is dissolved in water; temperature of around 30-40°C and air is kept out of the mixture (the product is impure and must be distilled to produce pure ethanol and the process takes a lot longer)

Question 23

What are the first 4 alcohols going from smallest to biggest?

Answer 23

Methanol (1 carbon), ethanol (2 carbons), propenol (3 carbons), butanol (4 carbons)

Question 24

What is the word equation for alcohol reacting with sodium?

Answer 24

Alcohol + sodium –> sodium alkoxide + hydrogen

Question 25

What is the functional group of carboxylic acids?

Answer 25

COOH

Question 26

What are the first four carboxylic acids going from smallest to biggest?

Answer 26

Methanoic acid (1 carbon), ethanoic acid (2 carbons), propanoic acid (3 carbons), butanoic acid (4 carbons)

Question 27

Why are carboxylic acids weak?

Answer 27

Because they only partially ionise in solution

Question 28

What is the word equation for carboxylic acids reacting with carbonates (starting with ethanoic acid + sodium carbonate)?

Answer 28

Ethanoic acid + sodium carbonate –> sodium ethanoate + carbon dioxide + water

Question 29

What is the word equation for carboxylic acids reacting with alcohol?

Answer 29

Carboxylic acid + alcohol <–> ester + water

Question 30

What are some uses of esters?

Answer 30

Perfumes, flavourings, solvents

Question 31

What are the properties of high density polyethene?

Answer 31

Uses a catalyst at 50°C and a lower pressure, made up of straighter molecules, stronger than low density polyethene, makes up plastics that are more dense, rigid and harder to melt

Question 32

What are the properties of low density polyethene?

Answer 32

Uses a temperature of 200°C and higher pressure, the polymer chains are branched out and can’t pack closely together, weaker than high density polyethene, makes up plastics that are light, soft and easier to melt

Question 33

What is thermosoftening plastic?

Answer 33

Plastic that can be melted and remoulded repeatedly

Question 34

What is thermosetting plastic?

Answer 34

Plastic that keeps its shape once heated and molded even if its heated again

Question 35

Why do thermosetting plastics keep their shape?

Answer 35

Because the monomers form covalent bonds between polymer chains when they are first heated

Question 36

What are some naturally occurring polymers?

Answer 36

Amino acids, DNA, cellulose, starch

Question 37

How can you test for the presence of an alkene?

Answer 37

Reacting it with bromine water, it will decolourise the bromine water from orange-yellow if the alkene is present