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AQA Chemistry > Quizlet > Flashcards

Quizlet Flashcards

1
Q

What is meant by the rate of chemical reactions

A

The speed at which reactants are made to products

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2
Q

How is the rate of reaction calculated

A
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3
Q

State the 5 factors affecting the rate of a chemical reaction

A

concentration of reactants pressure of gases surface area temperature catalysts

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4
Q

What is collision theory

A

Chemical reactions can occur only when reacting particles collide with eachother with sufficient energy

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5
Q

How does increasing the temperature effect the rate of reaction

A

the higher the temperature the faster the reaction As the temperature increases kinetic energy of the particles increases, also they move faster so they collide more frequently

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6
Q

How does concentration effect the rate of a reaction

A

If the concentration increases the reaction will be faster If there are more reactants there will be more frequent collisions

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7
Q

How does increasing the surface area increase the rate of reaction

A

If one of the reactants is a solid, then breaking it into smaller pieces will increase its surface area to volume ratio This means that for the same volume of the solid, the particles around it will have more area to work on - so there will be collisions more frequently

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8
Q

How does using a catalyst increase the speed of a reaction

A

They do this by decreasing the activation energy needed for the reaction to occur They do this by providing an alternative reaction pathway with a lower activation energy

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9
Q

What is a reversible reaction

A

When the products can react to form the reactants again

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10
Q

What will happen to the speed of the reaction as the reactants react

A

Their concentration fall so the forward reaction will slow down but as more and more products are made and thier rise, the backward reaction will speed up

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11
Q

What is equilibrium

A

The point at which the rates of the forward and backward reactions in a reversible reaction are the same, and so the amounts of reactants and products in the reaction container dont change

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12
Q

When is the only time that equilibrium can take place

A

If the reversible reaction takes place in a closed system which means that none of the reactants or products can escape and nothing else can get in

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13
Q

What does the position of equilibrium depend on

A

Temperature pressure concentration

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14
Q

How are reversible reactions affected by endo or exothermic reactions

A

In reversible reactions, if the reaction is endothermic in one direction it will be exothermic in the other The energy transferred from the surroundings by the endothermic reaction is equal to the energy transferred to the surroundings during the exothermic reaction

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15
Q

What le chateliers principle

A

The idea that if you change the conditions of a reversible reaction at equilibrium, the system will counteract the change It can be used to predict the effect of any changes you make to a reaction system

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16
Q

How do reversible reactions try to counteract changes to temperature

A

If you decrease the temperature, the equilibrium will move in the exothermic direction to produce more heat. This means you’ll get more products for the exothermic reaction and fewer products for the endothermic reaction. If you increase the temperature the equilibrium will move in the endothermic direction to try to decrease it. You’ll now get more products for the endothermic reaction and fewer products for the exothermic reaction.

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17
Q

How do reversible reactions try to counteract changes to pressure

A

Changing the pressure only affects the an equilibrium involving gases If you increase the pressure, the equilibrium tries to reduce it If you decrease the pressure, the equilibrium will try to increase it

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18
Q

How do reversible reactions try to counteract changes to concentration

A

If you change the concentration of either the reactants or the products, the system will no longer be at equilibrium. So the system responds to bring itself back to equilibrium again. If you increase the conc of the reactants, the system tries to decrease it by making more products and vice versa

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19
Q

What is a hydrocarbon

A

Any compound that is formed from carbon and hydrogen atoms only

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20
Q

What are alkanes and what are some of their properties

A

Alkanes are the simplest type of hydrocarbon you can get, they have the general formula CnHn+2 They are a homologous series they are saturated compounds

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21
Q

Methane

A
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22
Q

Ethane

A
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23
Q

Propane

A
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24
Q

Butane

A
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25
Q

Give some examples of how the properties of hydrocarbons change as the length of the hydrocarbons change

A

The shorter the chain: the more runny a hydrocarbon is, more volatile, more flammable, used as bottled gas for fuel

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26
Q

What happens during a complete combustion reaction and how are they used

A

both carbon and hydrogen from the hydrocarbon are oxidised hydrocarbons are used as fuels due to the amount of energy released when they combust completely

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27
Q

What is crude oil

A

Crude oil is a fossil fuel that is formed from the remains of plants and animals that died millions of years ago and were buried in mud

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28
Q

What are fossil fuels an example of

A

Non-renewable fuels, they take long to make and are being used up faster than they are being formed

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29
Q

What is crude oil a mixture of

A

Lots of different hydrocarbons most of which are alkanes

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30
Q

How are different compounds in crude oil seperated

A

fractional distillation

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31
Q

How does fractional distillation work

A

The oil is heated until most of it has turned to gas. the gas enters a fractionating columnThe longer hydrocarbons have higher boiling points so they condense back into liquid and drain out of the early on, when they are near the bottom. The shorter hydrocarbons have lower boiling points so they condense and drain out much later on, near to the top of the column where its coolerYou end up with the crude oil mixture seperated out into different fractions, each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms so they have similar boiling points

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32
Q

What is cracking

A

When hydrocarbons can be broken down to produce smaller, more useful molecules

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33
Q

What are the 2 types of cracking

A

catalytic cracking steam cracking

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34
Q

What are the products formed by cracking

A

Alkanes & alkenes

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35
Q

How does catalytic cracking work

A

Heat long chain hydrocarbons to vaporise them, vapour then passed over a hot powdered aluminium oxide catalyst The long chain molecules split apart on the surface of the specks of catalyst

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36
Q

How does steam cracking work

A

Vaporise them, mix them with steam and then heat them to a very high temperature

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37
Q

What are alkenes

A

Alkenes are hydrocarbons which have a double bond between 2 of the carbon atoms in their chain They are unsaturated

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38
Q

What is the general formula for alkenes

A
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39
Q

Ethene

A
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40
Q

Propene

A
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41
Q

Butene

A
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42
Q

Pentene

A
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43
Q

How do alkenes react most of the time

A

Addition reactions The carbon carbon double bond will open up will open up to leave a single bond and a new atom is added to each carbon

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44
Q

Addition reaction of hydrogen to an alkene

A

Hydrogen can react with the double bonded carbons to open up the double bond and form the equivalent, saturated alkane it reacts with hydrogen in the presence of a catalyst

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45
Q

How can steam react with alkenes to form alcohols

A

When alkenes react with steam, water is added across the double bond and an alcohol is formed Alcohol can be purified from the mixture by fractional distillation

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46
Q

How can halogens react with alkenes in addition reactions

A

They react with halogens such as bromine, chlorine and iodine, the molecules formed are saturated with the C=C carbons each becoming bonded to a halogen atom

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47
Q

How can the addition of bromine to a double bond be used to test for alkenes

A

When orange bromine water is added to a saturated compound like an alkane, no reaction will happen and it will stay bright orange whereas if its added to an alkene the bromine will add across the double bond, making a colourless dibromo-compound so the bromine water is decolourised

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48
Q

What are polymers

A

Polymers are long molecules formed when lots of small molecules called monomers join together which is called polymerisation

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49
Q

What 2 conditions is necessary for polymerisation

A

High pressure Presence of a catalyst

50
Q

What are addition ploymers formed from

A

Unsaturated monomers, like alkenes

51
Q

How do addition polymers form

A

The carbon carbon double bonds within the monomers break, and allow the two monomer molecules to bond to eachother

52
Q

What is the general formula for alcohols

A
53
Q

First 4 alcohols

A
54
Q

What are the 4 properties of alcohols

A

They are flammable They are all soluble in water They react with sodium to form hydrogen They oxidise to form carboxylic acids

55
Q

What are 4 things alcohols are used for

A

Alcoholic drinks Solvents Fuels

56
Q

Why are alcohols used as solvents

A

They can dissolve lots of different substances, including hydrocarbons, oils and fats

57
Q

What is the general word equation for the complete combustion of an alcohol

A
58
Q

What is fermentation

A

The anaerobic respiration of sugars by yeast cells to produce ethanol and carbon dioxide

59
Q

What is the word equation for the reaction of making ethanol by fermentation

A
60
Q

First 4 carboxylic acids

A
61
Q

How do carboxylic acids react with water

A

They dissolve in water but they dont completely ionise This means they form weak acidic solutions Which gives them a relatively high pH for an acid

62
Q

How do carboxylic acids react with carbonates

A

They form salt, water and carbon dioxide

63
Q

What type of substance reacts with an alcohol to form a carboxylic acid

A

An oxidising agent

64
Q

What is the functional of an ester

A

COO-

65
Q

What are esters formed from

A

Reacting an alcohol with a carboxylic acid

66
Q

What do we call the ester that is formed from ethanol and ethanoic acid

A

Ethyl ethanoate

67
Q

What is condensation polymerisation

A

The process by which monomers combine to form a polymer, while releasing small by-products such as water

68
Q

What is the general formula for making a polyester

A
69
Q

For polyesters, how does condensation polymerisation work

A

A diol and a dicarboxylic acid bond together As part of the process, the diol and dicarboxylic acid lose hydrogen and oxygen, which bond together to form water

70
Q

What does biodegradable mean

A

The substance can be broken down by naturally occurring organisms

71
Q

What 2 different functional groups are present in all amino acids

A

Amino group Carboxyl group

72
Q

How are polypeptides made

A

Condensation polymerisation between amino acids

73
Q

What is analytical chemistry

A

The science of seperating, identifying and quantifying different substances

74
Q

What is a chemically pure substance

A

A single element or compound that hasnt been mixed with any other substance

75
Q

How can impurities affect the melting and boiling points of the sample

A

Lower the melting point increase the boiling point increase the range over which a substance melts or boils

76
Q

What physical test can you do to check that a substance is pure

A

Heat it until it melts or boils. If it melts or boils at a specific temperature then its pure

77
Q

What is formulation

A

Mixtures that have been prepared using a specific formula

78
Q

What are formulations made from

A

Precise amounts of different components, and each component has a particular function

79
Q

What is flame emission spectroscopy used for

A

Identifying metal ions in solution, and measuring their concentration

80
Q

Outline the process for carrying out flame emission spectroscopy

A
81
Q

What are 3 advantages of using instrumental method instead of chemical tests

A

The instrumental method is very quick The instrumental method is very accurate The instrumental method is very sensitive

82
Q

What are the 3 disadvantages of using instrumental methods

A

Expensive Requires specialist training Requires a known comparison to check your reading against

83
Q

How long ago did the earth form

A

ABout 4.6 millions years ago

84
Q

What is the composition of our current atmosphere

A

78% Nitrogen 21% Oxygen other gases <1

85
Q

What are the 3 main stages in the evolution of earth’s atmosphere

A

Volcanoes emitted large amounts of gasEarth cooled, oceans formed, plants and algae evolvedPlants and algae produced oxygen, eventuall forming the atmosphere we have today

86
Q

How were oceans formed

A

After 1 billion years, the earth cooled, causing water vapour in the atmosphere to condense into liquid and form oceans

87
Q

What happened to most of the carbon dioxide in the early atmosphere

A

It dissolved in oceans The dissolved CO2 then went through a series of reactions to form carbonate precipitates These carbon precipitates formed sediments on the sea bed Some CO2 was also absorbed by green plants and algae so they could photosynthesise

88
Q

How are coal, crude oil and natural gas formed

A

Plants or algae absorb CO2 to use in photosynthesis When they die they dont decompose properly Under high temperatures and pressures, the organic material forms coal, crude oil and natural gas

89
Q

How has the atmosphere changed since the earth was formed

A
90
Q

What is global warming

A

The long term heating of earths atmosphere, observed since the pre-industrial period due to human activities

91
Q

What is climate change?

A

Long-term shifts in temperatures and weather patterns due to global warming

92
Q

Give 4 human activities that have affected the amount of greenhouse gases in the atmosphere

A

Deforestation Burning fossil fuels Farming of animals As microorganisms break down our waste in landfill sites, releases CO2

93
Q

Explain what the greenhouse effect is and how it works?

A
94
Q

What are some consequences of climate change

A

Melting ice caps Rising sea levels Reduced biodiversity Changed migration patterns increased extreme weather events

95
Q

What is a carbon footprint

A

The total amount of carbon dioxide and other greenhouse gases that are emitted over the full life cycle of a product, service or event

96
Q

Give 4 factors you would need to take into account when calculating the carbon footprint of a product such as a car

A

How all the raw materials were sourced The manufacturing process The total amount of fuel and other resources it will use over its lifetime How its disposed of

97
Q

Give 4 general ways we could reduce the carbon footprint of a product

A

Creating it using fewer, or more sustainable raw materials Use a more efficient manufacturing process Use renewable energy resources Recycle it rather than disposing of it in landfill

98
Q

How might governments help reduce carbon footprints

A

Introduce new laws or regulations Tax companies based on quantity of greenhouse gases they emit Put caps or limits on how many greenhouse gases companies can emit

99
Q

What pollutants can incomplete combustion produce

A

Carbon (soot) Carbon monoxide unburnt hydrocarbons

100
Q

How is soot in the air harmful

A

If inhaled it can get stuck in our lungs and cause damage, leading to respiratory problems It also cause smog/global dimming

101
Q

Why is carbon monoxide dangerous

A

It binds to haemoglobin so less oxygen is transported around the body Lack of oxygen causes fainting, a coma or even death It also has no smell or colour so its hard to detect

102
Q

How can the combustion of fossil fuels form sulfur dioxide

A

Some fossil fuels contain sulfur impurities - so when the fossil fuel is combusted, the sulfur becomes oxidised into sulfur dioxide

103
Q

How can the combustion of fossil fuels form nitrogen oxides

A

Combustion takes place in engines at high temperatures and pressures These conditions allow nitrogen and oxygen from the air to react together and form nitrogen oxides

104
Q

How does acid rain form

A

Nitrogen oxides and sulfur dioxide can dissolve in the water vapour in the atmosphere, forming dilute nitric or sulfuric acid, which falls as acid rain

105
Q

What are 3 negative effects of acid rain

A

Kills plants Damages buildings Corrodes statues

106
Q

What is a ceramic

A

A grouo if non metal solids with high boiling points that arent made from carbon based compounds

107
Q

How are clay ceramics made

A

Dig clay from the ground Mould the clay into the shape that you want Heat the clay at high temperatures in a furnace to harden it into a clay ceramic

108
Q

How is soda lime glass made

A

Heat a mixture of limestone, sand and sodium carbonate until it melts When it cools it will form glass

109
Q

How is borosilicate glass different to sodium lime glass

A

It is made from a mixture of sand and boron trioxide It has a higher melting pount than soda lime glass

110
Q

What is a composite material

A

Composites are made of one material (reinforcer) embedded in another (matrix) This makes the composite much stronger than either of the materials alone

111
Q

What is the difference between low density poly(ethene) and high density poly(ethene)

A
112
Q

What is the difference between thermosoftening and thermosetting polymers

A

Thermosoftening polymers melt when they are heated and can be remoulded Thermosetting polymers do not melt when they are heated, so cannot be remoulded

113
Q

How does the structure of thermosoftening polymers relate to their properties

A

Thermosoftening polymers are made from lots of polymer chains, held together by weak intermolecular forces These forces break easily when heated, causing the polymer to melt It can then be remoulded into a different shape and will harden again when cooled

114
Q

How does the structure of thermosetting polymers relate to their properties

A

Thermosetting polymers are made from lots of polymer chains, held together by strong covalent bonds These require lots of energy to break, so dont soften when heated These polymers are hard, strong and rigid

115
Q

What is corrosion

A

The process by which metals are slowly broken down by reacting with substances in their environment

116
Q

What is the word equation for the rusting of iron

A
117
Q

Why does iron corrode so much more than aluminium

A

When aluminium corrodes it forms a protective layer of aluminium oxide, which prevents further corrosion When iron corrodes, the hydrated iron(III) oxide flakes off, then the underlying iron also corrodes

118
Q

What are the two main methods of preventing rusting

A

Barrier methods Sacrificial methods

119
Q

What are 3 ways a barrier method might be applied to prevent rusting

A

Greasing Painting Electroplating

120
Q

What does electroplating do

A

Uses electrolysis to reduce metal ions onto an iron electrode - this process can be used to coat iron with a layer of another metal that wont corrode

AQA Chemistry (32 decks)

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