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(B - GCSE) Chemistry > C6.2 And C6.3 > Flashcards

C6.2 And C6.3 Flashcards

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1
Q

What is a hydrocarbon

A

A compound which only contains hydrogen and carbon

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2
Q

What is a homologous series

A

Organic compounds with the same functional group and general formula

Similar chemical reactions and physical properties

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3
Q

What is a functional group

A

An atom / group of atoms, or a type of bond which determined the chemical reactions of an organic compound

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4
Q

What is a general formula

A

Chemical formula showing the relative number of atoms of each element in a compound

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5
Q

What does saying ‘Alkanes are saturated’ mean

A

Their carbon atoms are joined by single bonds

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6
Q

What is the general formula for alkanes

A

C(n) H(2n+2)

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7
Q

What is an alkane

A

A hydrocarbon with the functional group of single carbon bonds

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8
Q

How many atoms are joined to one carbon atom

A

4

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9
Q

How do you model alkanes and alkenes

A

Using the displayed formula

Methane would be

H H-C-H
H
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10
Q

What does it mean if an alkene is described as unsaturated

A

It has a double bonded carbon atoms

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11
Q

How does the size of alkanes (small and big) affect these properties

Boiling point
Flammability
Cleanliness of flame
Viscosity

A

Small:
Low boiling
Very flammable
Clean flame
Low viscosity

Big:
High boiling
Harder to burn
Dirty sooty flame
High viscosity

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12
Q

What is complete combustion

A

Burning in a plentiful supply of oxygen

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13
Q

What is incomplete compustion

A

Burning in a limited supply of oxygen

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14
Q

What equation shows the complete combustion of an alkane (methane)

A

CH4 + 2 02 → CO2 + H20

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15
Q

What happens in the complete combustion of an alkane

A

Carbon atoms are oxidised to form carbon dioxide
Hydrogen atoms are oxidised to form water

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16
Q

What happens in the incomplete combustion of an alkane

A

Water is formed (hydrogen is oxidised)
Carbon cannot be fully oxidised to form carbon dioxide
Carbon monoxide is formed instead

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17
Q

Equation for incomplete combustion of an alkane (methane)

A

CH4 + 3/2 O2 → CO + 2 H2O

Or

2CH4 + 3O² → 2CO + 4H²O

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18
Q

What are alkenes

A

Alkenes are hydrocarbons with the functional group of double carbon bonds (unsaturated)

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19
Q

What is the general formula for alkenes

A

C(n)H(2n)

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20
Q

What are the first six prefixes for alkenes, alkanes, alcohols (etc)

A

Meth-
Eth-
Prop-
But-
Pent-
Hex-

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21
Q

What is an addition reaction

A

Reaction where an atom (or group of atoms) combines with a molecule to form a larger molecule with no other product

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22
Q

What is an addition polymer

A

Substance consisting of molecules made from many repeating units, formed by addition reactions

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23
Q

What happens to alkenes in addition reactions

A

The double carbon bond breaks and forms a single carbon bond

(At the end of the reaction there will still be 4 things bonded to each carbon atom)

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24
Q

Whay are alkenes reactive

A

Due to the carbon double bond which undergoes additions reactions

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25
Q

How can alkanes be formed from alkenes

A

A nickel catalyst is required

Alkene + hydrogen → alkane

E.g
Ethene + hydrogen → ethane

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26
Q

How can addition reactions be used to test for an alkene

A

Alkenes react with bromine to form a colourless compound called diobromethane

Bromine water (bromine dissolved in water) is brown, but this reaction with alkenes turns it colourless

The reaction does not work with alkanes

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27
Q

What happens in the hydration of an alkene

A

Adding water to an alkene makes it an alcohol

Ethene + water → ethanol

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28
Q

What is an alcohol

A

All alcohols are part of a homologous series

As they contain oxygen they are not hydrocarbons

They have a functional group of OH

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29
Q

What is the functional group of alcohols

A

OH

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30
Q

What is the general formula of alcohols

A

C(n)H(2n+1)OH

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31
Q

What happens in the complete combustion of an alcohol

A

Water vapour and carbon dioxide are produced

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32
Q

What happens in the incomplete combustion of an alcohol

A

Water vapour and carbon monoxide are produced

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33
Q

How are carboxylic acids made

A

By reacting alcohol with oxidising agents (e.g potassium manganate solution)

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34
Q

What is a carboxylic acid

A

An acid in a part of a homologous series

It has the functional group
COOH

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35
Q

What is the general formula for carboxylic acids

A

C(n)H(n+1)COOH

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36
Q

What are the main reactions of carboxylic acids

A

Metal + carboxylic acids → slat + hydrogen
Carboxylic acid + alkali → salt + water
Carboxylic acid + carbonate → salt + water + carbon dioxide

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37
Q

How can you test for an alcohol

A

Adding an oxidising agent such as potassium manganate will turn it onto a carboxylic acid

In this reaction there would be a colour change to clear

When doing this experiment wear gloves / eye protection as the reaction is violent

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38
Q

What is crude oil

A

A complex mixture of hydrocarbons (mostly alkanes) formed from the remains of dead organisms over millions of years

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39
Q

What is a finite resource

A

A resource which will run out eventually

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40
Q

What are fossil fuels

A

Fuels such as crude oil, natural gases and coal

They are formed from the remains of microorganisms over millions of years

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41
Q

How is crude oil useful

A

Using fractional distillation, different alkanes can be separated from crude oil.

These alkanes all have different uses (e.g petrol)

The fractionating column is hottest at the base

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42
Q

How are different fractions of crude oil colleceted

A

As the hydrocarbons have different boiling points they will travel different distances up the fractionating column.
They will then fall into trays (condense) and leave the column.

Lowest boiling point to highest
LPG
Petrol
Paraffin
Diesel
Heating oil
Fuel oil
Bitumen

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43
Q

What is cracking

A

Process of separating larger alkanes into smaller alkanes and alkenes through the use of high temperatures and a catalyst

44
Q

What temperatures and catalysts are used in cracking

A

600 to 700°C

Hot catalyst of alumina or silica

45
Q

How does cracking create a smaller alkane and an alkene

A

Covalent bonds between carbon atoms are broken at one point in the alkane

This leaves a smaller alkane and the additional polymer forms double carbon bonds (making an alkene)

46
Q

Why is cracking done

A

Smaller alkanes are more useful than larger ones, as they can ignite easier and flow better (making them better fuels)

Cracking allows oil refineries to produce enough small alkanes to match the demand for them

Alkenes are also produced and they can be used for making polymers

47
Q

Why is crude oil important

A

90% of it is used to produce fuels that are needed everyday (e.g petrol)

48
Q

What are addition reactions

A

Reactions where an atom / group of atoms combines with a molecule to form a larger molecule and NO other product

49
Q

What are addition polymers

A

A substance consisting of molecules made from many repeating units, formed by addition reactions

50
Q

What are repeating units

A

A section of a polymer that is repeated many times in the molecule

51
Q

What are polymerization reactions

A

A reaction where small monomers molecules join to make larger polymer molecules

52
Q

Why can alkenes be used in addition reactions and alkanes cannot

A

As the double carbon bond breaks and attaches to another carbon molecule

53
Q

How would you model propene being polymerised to poly propene (/ displayed formula

A

Propene is
H H H H
H-C-C=C Or C=C
H H H H CH3

[ H H ]
[ -C-C- ]
[ H CH3 ]
———– n
The letter n stands for how many repeating units there are

54
Q

What is DNA like

A

DNA is made of monomers called nucleotides

Contains a phosphate group
Sugar (deoxyribose)
An organic group ( nitrogenous base)

The bases are Adenine, thymine, cytosine, guanine

55
Q

How is DNA formed from nucleotides

A

The deoxyribose of one nucleotide binds with the phosphate of another to form a sugar phosphate backbone

Hydrogen bonds (intermolecular forces) form between opposite bases holding the stands together

56
Q

How are proteins formed

A

Proteins are polymers made from amino acids (20 amino acids)

Each amino acid has a reactive functional group at each end so they can join to form long protein molecules

57
Q

What are carbohydrates made of

A

They are compounds of carbon hydrogen and oxygen

They include simple sugars such as deoxyribose and sucrose and complex sugars such as starch.

Sucrose is made from two simple sugars, glucose and fructose

Starch is made of many simple sugar molecules joined together

58
Q

What is a condensation reaction

A

A reaction where two molecules join together to form a larger molecule and a smaller molecule (usually water or hydrogen chloride)

59
Q

What are condensation polymers

A

Substance with molecules made from many repeating units formed by condensation reactions

60
Q

What happens when a carboxylic acid an alcohol react

A

An ester and water is formed

61
Q

What is an ester

A

Organic molecules used for food flavourings

Often sweet smelling substances

62
Q

What are polyesters

A

Condensation polymers made of a carboxylic acid with two carboxyl groups and an alcohol with two hydroxyl groups

They contain many ester groups (COO)

63
Q

What are polyamides

A

Polymers made from a carboxylic acid with two carboxyl groups and an ‘amine’ with two amino groups

They contain many amide groups (CONH)

64
Q

What is needed for condensation polymerisation to occur

A

It can happen without a catalyst and at room temperature and standard pressure

65
Q

What is an amino functional group group

A

NH2

66
Q

What are chemical cells

A

Stores of chemical energy
They undergo exothermic reactions to produce P.D
When connected to a circuit current can flow
(Continues until reactants are used up)

67
Q

What are chemical cells made of

A

They are made of lithium
This material is expensive

68
Q

What are hydrogen fuel cells

A

A fuel cells that uses hydrogen.

Hydrogen reacts with oxygen to produce water vapour.
This is an exothermic reaction and electricity is produced

2H² (g)+ O²(g) → 2H²O(g)

69
Q

What are the environmental effects of chemical and fuel cells

A

Both require combustion of fossil fuels in their production
-chemical cells require heavy mining of rare metals

-Fuel cells require a toxic catalyst which is hard to dispose of

70
Q

Benefits of fuel and chemical cells

A

They produce less greenhouse gasses than using petrol or diesel

71
Q

What happens in a hydrogen fuel cell

A

Hydrogen enters the cell and loses an electron to the anode making it positive.

The hydrogen ions are small enough to pass through the proton exchange membrane
The electrons lost by the hydrogen travel through the external circuit

Hydrogen ions combine with oxygen and electrons at the other side (past the cathode) to form water vapour.

There is a catalyst in the proton exchange membrane

72
Q

Why is the proton exchange membrane called that

A

It is used to transfer (exchange) H+ ions

H+ ions are protons

73
Q

What are the ionic equations that occur in a fuel cell

A

2H² -4e- → 4H+(aq)

4H+(aq) + O²(g) → 2H²O

74
Q

What 3 gases make up 99.9% of the earth’s atmosphere

A

Nitrogen (78%)
Oxygen (21%)
Argon (0.9%)

75
Q

How was the earth’s atmosphere originally formed / what was it originally made of

A

Its believed to have been formed by volcanic activity

Volcanoes release a huge amount of carbon dioxide and water vapour.
As the earth cooled water vapour condensed to form oceans
This left am atmosphere predominantly made from burning fossil fuels

76
Q

How did the atmosphere change overtime /why

A

The amount of oxygen increased and carbon dioxide decreased due to photosynthesis completed by plants and algae.

This intially cause the oxidation of metals, but eventually lead to oxygen being released into the atmosphere

77
Q

What are pollutants

A

Substances released into the environment that may damage living things

78
Q

What are pollutants

A

Substance released into the environment that may cause harm to living things

79
Q

How do most atmospheric pollutants enter the air

A

By the burning of fossil fuels

80
Q

Why is carbon monoxide a pollutant

A

It is released through the incomplete combustion of coal / wood / natural gases

When breathed in it binds to haemoglobin in red blood cells reducing oxygen in your blood stream.
Carbon monoxide poisoning causes drowsiness, difficulty breathing and death

81
Q

What are particulates

A

Small particles (mostly carbon) formed by incomplete combustion

82
Q

What problems do particulate caused

A

When breathed in they settle deep in the lungs.

This can cause bronchitis and other breathing problems + increases heart disease

83
Q

Why di acidic oxides (e.g nitrogen dioxide) cause problems (+sulfur dioxide)

A

They dissolve into the moisture in clouds and fall as acidic rain

Acid rain corrodes stonework and corrodes metals
It can kill trees and living things in rivers

Sulfur dioxide is formed when sulfur reacts with oxygen when fossil fuels are combusted
They can cause acid rain

84
Q

What is the greenhouse effect

A

The interaction of infrared radiation in the air and molecules in the atmosphere reducing the transfer of energy to space

85
Q

What are greenhouse gases

A

Gas in the atmosphere that reduces the transfer of energy to space by infrared radiation

86
Q

What is global warming

A

Worldwide increase in temperature over time

87
Q

Examples of greenhouse gasses

A

Water vapour
Carbon dioxide
Methane

88
Q

How does the greenhouse effect work

A

Energy transferred by radiation reaches the sun

The radiation increases the earths temperature

Infrared radiation is emitted by the earth, some goes into space and some is absorbed by greenhouse gas molecules in the atmosphere

Infrared radiation is emitted by greenhouse gas particles in all directions, warming the surface of the earth

89
Q

How are greenhouse gasses released into the air by human activities

A

Carbon dioxide - combustion of fossil fuels

Methane - rice paddy fields, cattle, landfill sites, use of natural gas

90
Q

What is the advanced greenhouse effect

A

By releasing greenhouse gases into the atmosphere we are increasing the concentration of them in the atmosphere

This leads to earth’s temperatures increasing further

91
Q

What is climate change

A

Long - term change in climate patterns

92
Q

What will global warming do to the earth

A

Results in an increased temperature
Altered weather patterns cause flooding and problems of disease / pests

Ice caps melt and rising sea levels

93
Q

How are greenhouse emissions reduced

A

Consumption of fossil fuels is reduced by using biofuels

Renewable energy resources are used to generate electricity

Carbon dioxide is prevented from entering the atmosphere using carbon capture and storgae

94
Q

Why are the emissions of water vapour not seen as an issue

A

As it has a very low effect on warming the earth + lots of it falls back as rain

95
Q

Where does most drinking water come from

A

Lakes reservoirs and aquifers

96
Q

What is an aquifer

A

Layer of rock that stores water underground

97
Q

What is potable water

A

Water that is safe to drink

98
Q

What is desalinisation

A

Process of removing dissolved salts from water

99
Q

How is small scale and large scale desalinisation doen

A

Large - using distillation
Small - ‘reverse osmosis’ to filter out the salts

100
Q

Why is desalinisation not used in the uk

A

As supplies of freshwater are not limited and the cost

101
Q

How is water usually treated

A

1) water is ‘screened’ (passed through close bars of metal) to remove large objects such as leaves and branches.

2) (clarification) Settlement tanks are used to remove soil and sand, aluminum sulfate and like are also added to remove silt and sludge (they clump the particles together - sink to the bottom)

3) (Filtering) Dirty water is passed through a filter trapping undissolved solids (gravel beds or sand are often used to filter)

4) Bacteria is finally killed by adding small amounts of chlorine

102
Q

Why is Fluoride added to water (in some areas)

A

It strengthens teeth preventing cavity loss
Combats tooth decay in children

103
Q

Negatives of fluoridation (adding fluoride to water)

A

Causes discolouring of teeth ( yellow teeth )
Causes damage to soft tissue such as gums

104
Q

How can hydrogen be made from alkanes

A

Alkane + water → carbon monoxide + hydrogen

105
Q

What happens in the comete and incomplete combustion of alkenes

A

Complete
Alkene + oxygen → carbon dioxide and water (same reaction as alkanes)

Incomplete
Alkene + oxygen → carbon + carbon monoxide + water (different to alkanes)

(B - GCSE) Chemistry (7 decks)

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