topic 7 year 11 organic chemistry Flashcards

1
Q

what are hydrocarbons

A

compounds formed from carbon and hydrogen atoms only

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2
Q

what are alkanes

A
  • A simple type of hydrocarbon

- saturated compounds

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3
Q

In alkanes how many covalent bonds does each carbon atom form

A

4 covalent bonds

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4
Q

What is the formula for alkanes

A

C(n)H (2n+2)

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5
Q

When does complete combustion occur

A

Where there is plenty of oxygen

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6
Q

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

A

Lots of oxygen-this makes them as useful fuels

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7
Q

Hydrocarbon + oxygen ➡️

A

Carbon dioxide + water

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8
Q

What happens to the hydrogen and carbon in hydrocarbon during combustion

A

They are both OXIDISED

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9
Q

What is oxidation

A

The gain of oxygen

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10
Q

What is crude oil

A

A fossil fuel found in rocks

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11
Q

What can fossil fuels be used as a source of

A

Energy

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12
Q

Fossil fuels are

A

Non-renewable

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13
Q

What does oil provide in modern day

A

Fuel for cars,lorries, transport

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14
Q

What other things except from fuel is made from crude oil

A
  • kerosene
  • LPG
  • diesel oil
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15
Q

What are petrochemicals

A

Compounds that come from crude oil

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16
Q

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

A

Organic compounds

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17
Q

What are most of the organic compounds in crude oil

A

Hydrocarbon

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18
Q

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

A

Homologous series

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19
Q

what series are the alkanes part of

A

the homologous series

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20
Q

what is a homologous series

A

a group of organic compounds that react in a similar way

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21
Q

what are the first 4 alkanes (MEPB)

A
  • METHANE
  • ETHANE
  • PROPANE
  • BUTANE
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22
Q

what is the formula for methane

A

CH4

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23
Q

what is the formula for ethane

A

C2H6

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24
Q

what is the formula for propane

A

C3H8

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25
Q

what is the formula for butane

A

C4H10

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26
Q

If the length of the hydrocarbon changes what happens

A

the properties of the hydrocarbons change

27
Q

the shorter the carbon chain… (4)

A
  • the more runny a hydrocarbon
  • less viscous (gloopy) it is
  • more volatile it is (lower boiling points)
  • more flammable (easy to ignite)
28
Q

what are short hydrocarbons with low boiling points used for

A

bottled gas

29
Q

when does complete combustion occur

A

when there is plenty of oxygen

30
Q

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

A

they are oxidised

31
Q

why are hydrocarbons used as fuels

A

due to the amount of energy released when they combust completely

32
Q

by what process is crude oil separated by

A

fractional disillation

33
Q

what is crude oil

A

a fossil fuel

34
Q

how is crude oil formed

A
  • 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
35
Q

give 3 examples of fossil fuels

A

coal, oil and gas

36
Q

why are fossil fuels bad

A
  • non-renewable

- run out

37
Q

what is crude oil

A

a mixture of lots of different types of hydrocarbons

38
Q

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

A
  • 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

39
Q

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

A

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

40
Q

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

A
  • 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
41
Q

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

A
  • 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
42
Q

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

A

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

43
Q

what are the compounds you get from crude oil known as

A

organic compounds (carbon atoms only)

44
Q

why are short-chained hydrocarbons in high demand

A

because they are flammable and make good fuels

45
Q

why are long chained hydrocarbons not in high demand

A

because they form thick gloopy liquids like tar

46
Q

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

A

by cracking

47
Q

what other molecule does cracking produce other than alkanes

A

alkenes

48
Q

what can we use to test for alkenes

A

bromine water

49
Q

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

A

colourless

50
Q

what are the 2 types of cracking methods

A
  • thermal decomposition

- steam cracking

51
Q

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

A
  • 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
52
Q

what is steam cracking

A

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

53
Q

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

A

Single covalent bonds

54
Q

What happens in cracking

A

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

55
Q

What type of bond do alkanes have between the carbon atoms

A

Single covalent bonds

56
Q

2 features of short chain hydrocarbons

A
  • highly flammable

- low boiling points

57
Q

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

A
  • they become LESS flammable
  • boiling point INCREASES
  • HIGH viscosity
58
Q

During combustion why does the hydrogen and carbon atoms become oxidised

A

Because they react with oxygen

59
Q

Why do large hydrocarbon molecules not make good fuels

A

Because they are not very flammable

60
Q

What 2 things do we use in catalytic cracking

A
  • heat

- a catalyst

61
Q

What does the catalyst do catalytic cracking

A

Speeds up the reaction

62
Q

What 2 things do we use in steam cracking

A
  • heat

- steam

63
Q

Alkenes are more …. than alkanes

A

Reactive

64
Q

The fractions in fractional distillation contain …

A

Hydrocarbons with similar number of carbon atoms