topic 7 year 11 organic chemistry

Question 1

what are hydrocarbons

Answer 1

compounds formed from carbon and hydrogen atoms only

Question 2

what are alkanes

Answer 2

• A simple type of hydrocarbon

- saturated compounds

Question 3

In alkanes how many covalent bonds does each carbon atom form

Answer 3

4 covalent bonds

Question 4

What is the formula for alkanes

Answer 4

C(n)H (2n+2)

Question 5

When does complete combustion occur

Answer 5

Where there is plenty of oxygen

Question 6

What does the complete combustion of a hydrocarbon in oxygen release, what does make them useful as

Answer 6

Lots of oxygen-this makes them as useful fuels

Question 7

Hydrocarbon + oxygen ➡️

Answer 7

Carbon dioxide + water

Question 8

What happens to the hydrogen and carbon in hydrocarbon during combustion

Answer 8

They are both OXIDISED

Question 9

What is oxidation

Answer 9

The gain of oxygen

Question 10

What is crude oil

Answer 10

A fossil fuel found in rocks

Question 11

What can fossil fuels be used as a source of

Answer 11

Energy

Question 12

Fossil fuels are

Answer 12

Non-renewable

Question 13

What does oil provide in modern day

Answer 13

Fuel for cars,lorries, transport

Question 14

What other things except from fuel is made from crude oil

Answer 14

• kerosene
• LPG
• diesel oil

Question 15

What are petrochemicals

Answer 15

Compounds that come from crude oil

Question 16

What are all the products that you get from crude oil examples of

Answer 16

Organic compounds

Question 17

What are most of the organic compounds in crude oil

Answer 17

Hydrocarbon

Question 18

What can carbon atoms bond together to form different groups of called …

Answer 18

Homologous series

Question 19

what series are the alkanes part of

Answer 19

the homologous series

Question 20

what is a homologous series

Answer 20

a group of organic compounds that react in a similar way

Question 21

what are the first 4 alkanes (MEPB)

Answer 21

• METHANE
• ETHANE
• PROPANE
• BUTANE

Question 22

what is the formula for methane

Answer 22

CH4

Question 23

what is the formula for ethane

Answer 23

C2H6

Question 24

what is the formula for propane

Answer 24

C3H8

Question 25

what is the formula for butane

Answer 25

C4H10

Question 26

If the length of the hydrocarbon changes what happens

Answer 26

the properties of the hydrocarbons change

Question 27

the shorter the carbon chain... (4)

Answer 27

- the more runny a hydrocarbon - less viscous (gloopy) it is - more volatile it is (lower boiling points) - more flammable (easy to ignite)

Question 28

what are short hydrocarbons with low boiling points used for

Answer 28

bottled gas

Question 29

when does complete combustion occur

Answer 29

when there is plenty of oxygen

Question 30

during combustion, what happens to the hydrogen and carbon from hydrocarbon

Answer 30

they are oxidised

Question 31

why are hydrocarbons used as fuels

Answer 31

due to the amount of energy released when they combust completely

Question 32

by what process is crude oil separated by

Answer 32

fractional disillation

Question 33

what is crude oil

Answer 33

a fossil fuel

Question 34

how is crude oil formed

Answer 34

- from the remains of dead plants and animals mainly plankton that died millions of years ago and were buried in mud - over millions of years, with high temps and pressure, the remains turn into crude oil which can be dried up from the rocks

Question 35

give 3 examples of fossil fuels

Answer 35

coal, oil and gas

Question 36

why are fossil fuels bad

Answer 36

- non-renewable | - run out

Question 37

what is crude oil

Answer 37

a mixture of lots of different types of hydrocarbons

Question 38

give the 1st step to how fractional distillation works (the oil)

Answer 38

- the oil is heated up until most of it turns into gas | - the gases enter a fractionating column where the liquid bit is drained off

Question 39

give the second step to how fractional distillation works (temp gradient)

Answer 39

-in the column there is a temp gradient (it's hot at the bottom and gets cooler as you go up)

Question 40

give the 3rd step to how fractional distillation works (longer and shorter hydrocarbons)

Answer 40

- the longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column earlier on, where they're near the bottom - the shorter hydrocarbons have lower boiling points and. They condense and drain out much later on, near to the top of the column where it is cooler

Question 41

give the 4th step to how fractional distillation works (crude oil and fractions)

Answer 41

- you end up with crude oil mixture separated out into different fractions - each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points

Question 42

what does the PETROCHEMICAL industry use the hydrocarbons from crude oil as

Answer 42

feedstock to make new compounds for use in things like polymers, solvents, detergents and lubricants

Question 43

what are the compounds you get from crude oil known as

Answer 43

organic compounds (carbon atoms only)

Question 44

why are short-chained hydrocarbons in high demand

Answer 44

because they are flammable and make good fuels

Question 45

why are long chained hydrocarbons not in high demand

Answer 45

because they form thick gloopy liquids like tar

Question 46

by what process is long-chained molecules turned into shorter ones

Answer 46

by cracking

Question 47

what other molecule does cracking produce other than alkanes

Answer 47

alkenes

Question 48

what can we use to test for alkenes

Answer 48

bromine water

Question 49

if bromine water is added to alkenes what colour does it change to

Answer 49

colourless

Question 50

what are the 2 types of cracking methods

Answer 50

- thermal decomposition | - steam cracking

Question 51

what is thermal decomposition- explain how to do it and what happens

Answer 51

- breaking molecules down by heating them - the first step is to heat long-chain hydrocarbons to VAPORISE them(turning them into gas) - then the vapour is passed over a hot powdered aluminium oxide catalyst

Question 52

what is steam cracking

Answer 52

-vaporising and mixing hydrocarbons with steam and then heating them to a very high temp

Question 53

What type of bonds are there between alkanes and the carbon atoms

Answer 53

Single covalent bonds

Question 54

What happens in cracking

Answer 54

A large alkane molecule is broken down (cracked) to produce smaller, more useful molecules

Question 55

What type of bond do alkanes have between the carbon atoms

Answer 55

Single covalent bonds

Question 56

2 features of short chain hydrocarbons

Answer 56

- highly flammable | - low boiling points

Question 57

As the hydrocarbon molecules get longer what happens to them (3)

Answer 57

- they become LESS flammable - boiling point INCREASES - HIGH viscosity

Question 58

During combustion why does the hydrogen and carbon atoms become oxidised

Answer 58

Because they react with oxygen

Question 59

Why do large hydrocarbon molecules not make good fuels

Answer 59

Because they are not very flammable

Question 60

What 2 things do we use in catalytic cracking

Answer 60

- heat | - a catalyst

Question 61

What does the catalyst do catalytic cracking

Answer 61

Speeds up the reaction

Question 62

What 2 things do we use in steam cracking

Answer 62

- heat | - steam

Question 63

Alkenes are more .... than alkanes

Answer 63

Reactive

Question 64

The fractions in fractional distillation contain ...

Answer 64

Hydrocarbons with similar number of carbon atoms