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IGCSE Chemistry > C14 - Organic chemistry > Flashcards

C14 - Organic chemistry Flashcards

1
Q

What is a hydrocarbon

A

an organic compound made up of purely hydrogen and carbon

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2
Q

what are the properties of short and long chained hydrocarbons

A

short chained: lower melting point, lower viscosity, more flammable
Long chained: Higher melting point, higher viscosity, less flammable

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3
Q

Fractional distillation separates

A

crude oil into simpler, more useful mixtures.

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4
Q

Naphtha (in between gasoline and kerosene) used for

A

making chemicals.

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5
Q

Lubricating oil (in between fuel oil and bitumen) used for

A

lubricants, waxes and polishes.

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6
Q

Petrol use

A

fuel for cars

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7
Q

refinery gas use

A

domestic heating and cooking

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8
Q

kerosene use

A

fuel for aircrafts

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9
Q

Diesel oil use

A

cars and trains

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10
Q

fuel oil use

A

fuel for ships and power stations

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11
Q

Bitumen use

A

surfacing roads and roofs

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12
Q

How does fractional distillation separate crude oils

A

it is heated in a furnace and passed into the bottom of a fractionating column. It gives off mixtures of vapors that rise up the column and different fractions condense at different heights in which the liquids are collected at trays.

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13
Q

The homologous series is a series of

A

compounds with the same general formula and similar chemical properties

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14
Q

The physical properties that can change in a homologous series

A

As chains get longer boiling points increase

Each new chain adds on another CH2

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15
Q

why does the boiling point of hydrocarbons increase as chains get longer

A

because there are more and more intermolecular forces between the molecules (although weak still add up)

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16
Q

what is the alkane molecular structure

A

carbon atoms are bonded to 4 other atoms (hydrogen or carbon)

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17
Q

alkanes are called saturated hydrocarbons because

A

they only contain single bonds with other atoms

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18
Q

Uses of alkanes

A

They are unreactive

they can burn well making them a good source for fuel

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19
Q

General formula for alkane

A

CnH(2n+2) (For example: if hydrocarbon has 7 carbons than the formula is C7H16

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20
Q

Alkanes will react with chlorine in the presence of a

A

UV light which activates the chlorine to react

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21
Q

The reaction between alkane and chlorine is called

A

substitution reaction as one hydrogen atom in the hydrocarbon is replaced with one chlorine atom

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22
Q

the products of a alkane chlorine reaction are

A

chloroalkane + hydrogen chloride

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23
Q

What are the 4 smallest hydrocarbons in ascending order

A

methane, ethane, propane, butane

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24
Q

In an abundant supply of air alkanes burn to form

A

CO2 + water and is called complete combustion of alkanes in which a blue flame will be present

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25
Q

word and symbol equation for the complete combustion of alkanes

A

methane + oxygen ==> carbon dioxide + water

CH4(g) + 2O2(g) ==> CO2(g) + 2H2O(l)

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26
Q

When oxygen supply is limited incomplete combustion occurs in which the presence of a

A

yellow flame to show that

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27
Q

word and symbol equation for the incomplete combustion of alkanes

A

methane + oxygen ==> carbon + water

CH4(g) + O2(g) ==> C(g) + 2H2O(l)

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28
Q

Incomplete combustion of hydrocarbon can be dangerous because it can produce

A

carbon monoxide which is poisonous

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29
Q

Heavy Fractions of Crude Oil do not make good fuels as they

A

have low volatility, do not ignite easily and have high boiling points

30
Q

What is the process of cracking

A

breaking down long chains of hydrocarbons into smaller more useful molecules. It is an example of thermal decomposition

31
Q

What are the products of cracking

A

an alkane and an alkene

32
Q

What are the requirements to perform cracking

A

a higher temperature of around 600 - 700 C

a catalyst of silica or alumina

33
Q

Alkenes are another

A

homologous series which have similar chemical and physical properties that change gradually from one member to the next

34
Q

Alkenes are a functional group C=C meaning

A

they have a carbon-carbon double bond

35
Q

Properties and uses of alkenes

A

More reactive than alkanes
General molecular formula of CnH2n
They are unsaturated hydrocarbons because they contain a double bond between 2 C atoms
Uses: Making polymers such as polythene
Burn in oxygen to form CO2 and H2O and CO if oxygen is limited

36
Q

Alkenes are involved in

A

addition reactions

37
Q

Hydrogen can be added to an alkene to make an

A

alkane

38
Q

What are the requirements for an addition reaction between hydrogen and an alkene

A

A nickel catalyst
150 C temperature
H2

39
Q

Word and symbol equation for addition reaction between hydrogen and an alkene

A

Ethene + hydrogen ==> ethane

C2H4 + H2 ==> C2H6

40
Q

What test could you use to distinguish alkenes from alkanes or saturated hydrocarbon from unsaturated hydrocarbon

A

Add bromine water to hydrocarbon. Alkanes will not react with it in which there will be no color change but an alkene will react with bromine turning the color from orange to colorless.

41
Q

What is the word equation for an addition reaction between bromine and alkene

A

Ethene + Bromine ==> 1,2 -dibromoethane

C2H4 + Br2 ==> C2H4Br2

42
Q

Ethene can also react with steam to form

A

ethanol

43
Q

What are the requirements for a reaction between steam and ethene

A

Phosphoric acid catalyst
300 C and 70 atm
H20

44
Q

What is the word equation for an addition reaction between steam and ethene

A

ethene + steam ==> ethanol

C2H4 + H2O ==> C2H5OH

45
Q

what is an isomer

A

isomer is same molecular formula but different structural formula

46
Q

Alcohol properties and characteristics

A

functional group of alcohols is a hydroxyl group OH
They can be dehydrated to form alkenes
Ethanoic and butanoic acids react the same with metals meaning alcohols react similar ways
General formula (CnH2n + 1 OH)

47
Q

Reactions of a ethanol with air forms

A

CO2 + H2O

48
Q

ethanol + oxygen ==>

C2H5OH + 3O2 ==>

A

carbon dioxide + water

2CO2 + 3H2O

49
Q

Uses of ethanol

A

Solvent - such as in disinfectants and perfumes
Fuel - such as cars
Alcoholic drinks - such as wine, beer and spirits

50
Q

Ethanol can be made via

A

fermentation or addition of steam

51
Q

In fermentation the reactant involved is

A

sugar and yeast. The sugar can be from barley in beer making and grapes from wine making.

52
Q

Why is yeast used in fermentation

A

yeast contains an enzyme which acts as a catalyst breaking down the sugars in a much faster rate.

53
Q

What are the requirements for fermentation

A

Temperature of around 25 - 30 C some say 37 C

54
Q

What is the formula for sugar (glucose)

A

C6H12O6

55
Q

What is the word and symbol equation for fermentation

A

sugar ==> ethanol + carbon dioxide

C6H12O6 ==> 2C2H5OH + 2CO2

56
Q

What are the advantages and disadvantages of making ethanol from fermentation and from addition of steam

A

Fermentation: Plant sugars and renewable however creates waste products of CO2
Addition of steam: Fast and efficient however ethene is cracked from crude oil which is non-renewable and also requires a lot of energy.

57
Q

What is a polymer

A

a long chained molecule formed from small units called monomers

58
Q

Manufactured polymers are called

A

synthetic polymers

59
Q

Common synthetic polymers include

A

plastics such as polythene and fabrics using clothing from polyester or polyamide.

60
Q

What are the two types of synthetic polymers

A

addition and condensation polymers

61
Q

polymers are held by

A

strong covalent bonds but weak intermolecular forces

62
Q

Polymers melt easily because

A

there are weak intermolecular forces which can be broken down easily

63
Q

Alkenes are monomers used

A

in addition polymerization because they can open up their double bonded carbon atoms and attach to other molecules forming chains of monomers

64
Q

when ethene monomers undergo addition polymerization the product is

A

poly (ethene)

65
Q

Condensation polymers are polymers made up of

A

2 different monomers reacting together

66
Q

When the two monomers react in condensation polymers they expel a

A

small molecule which is water

67
Q

Nylon is a

A

common synthetic condensation polymer

68
Q

Nylon is made from a molecule with

A

carboxylic acid (COOH) and another molecule (NH2) and they react to form an amide link

69
Q

Show ethene in a symbol equation for addition polymerization

A

nCH2 = CH2 ==> [CH2CH2]n
the n represents the repeating unit
the double bond “=” breaks and is replaced with “[]”

70
Q

what is the difference between additional and condensation polymerization

A

additional polymerization results in the addition of many of the same monomers whilst condensation involves two different types of monomers which when reacted expel a molecule of water.

IGCSE Chemistry (16 decks)

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