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GCSE Chemistry > Paper 2 > Flashcards

Paper 2 Flashcards

1
Q

How do you calculate rate?

A

amount of product made (grams/cm3/moles) / time

or

amount of reactant used / time

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2
Q

Give the five factors that affect rate.

A

Temperature
Concentration of solutions
Pressure in gases
Surface area in a solid
Catalyst

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3
Q

How do you measure rate with disappearing metal?

A

Time how long it takes for the metal to disappear

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4
Q

How do you measure rate with the upside down measuring cylinder?

A

Time how long it takes for the metal to disappear

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5
Q

How do you measure rate using a gas syringe?

A

Measure volume of gas in the gas syringe in a given time

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6
Q

How do you measure rate using a balance?

A

Measure how much the mass decreases by in a certain length of time

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7
Q

How do you measure rate using a disappearing cross?

A

Time how long it takes for the cross to disappear

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8
Q

What needs to happen for a chemical reaction to take place?

A

The particles have to collide with enough force or energy

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9
Q

What is activation energy?

A

Minimum amount of energy needed to start a chemical reaction

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10
Q

What does rate depend on?

A

Frequency of collisions

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11
Q

What is the relationship between rate and surface area?

A

The larger the surface area, the higher the rate of reaction because there will be a higher frequency of collisions

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12
Q

How does particle size affect surface area?

A

The smaller the particle, the more surface area it will have compared to a larger particle with the same volume

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13
Q

How does temperature affect rate?

A

The higher the temperature, the faster the rate of reaction as, when particles heat up, they gain more kinetic energy, causing them to collide more frequently with each other. As the particles have more energy, more of the collisions are successful.

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14
Q

What is concentration?

A

The amount of solid dissolved in a certain volume.

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15
Q

During the disappearing cross practical, what makes the reaction go cloudy?

A

Solid sulphur

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16
Q

How does concentration affect rate?

A

Higher concentrations have more particles per unit volume, which increases the frequency of collisions.

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17
Q

What is a catalyst?

A

A substance that speeds up a reaction without being used up.

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18
Q

How do catalysts work?

A

They lower the activation energy by providing a different pathway for the reaction to happen.

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19
Q

In rate graphs, the steeper the line, the ______ the reaction.

A

Faster

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20
Q

What happens to rate over the course of the reaction?

A

Slows down

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21
Q

What does height depend on in rate graphs?

A

Volume and concentration

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22
Q

Calcium carbonate + hydrochloric acid -> ____ _____ + _____ + _____ ______

A

Calcium chloride + water + carbon dioxide

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23
Q

What happens in a reversible reaction?

A

The reactants turn into products and the products can turn back into the reactants

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24
Q

How can you change the direction of the reversible reaction?

A

By changing the conditions

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25
Q

Different directions in reversible reactions are what kinds of reactions?

A

One direction is exothermic and the other is endothermic

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26
Q

How does pressure affect rate?

A

The higher the pressure, the faster the reaction. The particles are closer together which increases the frequency of collisions.

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27
Q

What happens at equilibrium?

A

At equilibrium, the forward and backward reaction are happening at the same time and at the same rate in a closed system.

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28
Q

What is a closed system?

A

Closed system means nothing can enter or leave

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29
Q

What does it mean if the equilibrium is to the left?

A

There are more reactants than products

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30
Q

What does it mean if the equilibrium is to the right?

A

There are more products than reactants

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31
Q

What conditions can move the equilibrium’s position?

A

Temperature
Pressure (in a gas)
Concentration

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32
Q

What is Le Chatelier’s principle?

A

The equilibrium will shift to oppose the change in conditions

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33
Q

What happens to the equilibrium if the concentration of reactants increases?

A

Equilibrium with shift right and make more product

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34
Q

What happens to the equilibrium if the concentration of reactants decreases?

A

Equilibrium will shift left and make more reactant

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35
Q

What happens to the equilibrium if the concentration of products increases?

A

Equilibrium will shift left and make more reactant

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36
Q

What happens to the equilibrium if the concentration of products decreases?

A

Equilibrium will shift right and make more product

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37
Q

How does pressure affect equilibrium?

A

A high pressure will shift the equilibrium to the side with the lowest number of molecules.
A low pressure will shift the equilibrium to the side with the most molecules.

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38
Q

How does pressure affect equilibrium if the reactants and the products have the same number of molecules?

A

It won’t affect equilibrium. Nothing happens.

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39
Q

How does temperature affect equilibrium?

A

A high temperature means the equilibrium shifts in the endothermic direction, and a low temperature means the equilibrium shifts in the exothermic direction.

40
Q

What is a pure substance?

A

A substance that is made of only one type of atom or only one type of molecule.

41
Q

What is a formulation in chemistry?

A

A mixture designed as a useful purpose.

42
Q

What is the purpose of chromatography?

A

Used to separate different coloured inks

43
Q

What is the mobile phase?

A

Solvent

44
Q

What is the stationary phase?

A

Paper

45
Q

What happens if the colour is more attracted to the mobile phase?

A

Moves higher up the paper.

46
Q

What are some common issues with chromatography?

A

The start line needs to be drawn in pencil as it won’t run, unlike pen.
The solvent needs to be below the pencil line as if it’s above the line, the colours dissolve in the solvent.
Some solvents need a lid otherwise they’d evaporate and the inks wouldn’t move up the paper.

47
Q

How do you calculate Rf value?

A

Measure to the middle of the spot.

distance travelled by spot / distance travelled by solvent

48
Q

How can you tell if an ink is pure?

A

Only has one spot above the line

49
Q

What does two or more spots above the line mean?

A

It’s a mixture

50
Q

How do you know if colours are the same in chromatography?

A

If spots move to the same height and have the same Rf value, they’re the same colour.

51
Q

How can you test for hydrogen?

A

Lit splint and positive result is a squeaky pop

52
Q

How can you test for oxygen?

A

Glowing splint and positive result is that the splint relights

53
Q

How can you test for carbon dioxide?

A

Bubble into limewater and positive result is it turns cloudy

54
Q

How can you test for chlorine?

A

Damp litmus paper and positive result is the paper is bleached

55
Q

What is a finite resource?

A

A resource that cannot be replaced once it has been used

56
Q

What is a renewable resource?

A

A resource that we can replace once we have used it

57
Q

What is a sustainable development?

A

Using resources to meet the needs of people today without preventing people in the future from meeting theirs

58
Q

What is pure water?

A

Only contains water molecules and nothing else

59
Q

What is potable water?

A

Water that’s safe to drink

60
Q

What is fresh water?

A

Water found in places such as lakes, rivers, glaciers etc

61
Q

What is ground water?

A

Fresh water found in underground streams

62
Q

What is sea water?

A

Water in seas and oceans

63
Q

What is waste water?

A

Used water from homes and industry

64
Q

How can you get potable water from fresh/ground water?

A

Choose a source of fresh water or ground water.
Pass the water through filter beds to remove solids.
Sterilise by using chlorine, UV light, or ozone to kill microbes.

65
Q

What is desalination?

A

Process to remove dissolved substances from sea water.

66
Q

How do you get pure water from salt water using distillation?

A

The salt water is heated and evaporated, then the water vapour is cooled and condensed into pure water. This is expensive as it uses a lot of energy.

67
Q

How do you get pure water from salt water using reverse osmosis?

A

Reverse osmosis works by applying a pressure to salt water to force it through a semi-permeable membrane. The semi-permeable membrane has small enough holes that only the water passes through. This is expensive as it uses lots of energy to produce the pressure.

68
Q

Where does waste water come from?

A

Domestic, industrial and agricultural uses of water

69
Q

How is waste water collected and what happens once it’s been collected?

A

It’s collected in underground pipes (sewers) and taken for treatment

70
Q

How is waste water treated?

A

Screening and grit removal - removed large solids.
Sedimentation - separates human waste from the water (effluent)
Aerobic treatment of effluent - air is passed through the effluent in aeration tanks, leading to good bacteria killing harmful bacteria.
Anaerobic treatment of sludge - without air, bacteria produce methane from sludge, which can then be burned for heat/electricity generation.

71
Q

What is an ore?

A

A rock that contains enough metal to be extracted for a profit

72
Q

Why are bioleaching and phytomining necessary?

A

High grade copper ores are running out so we now extract copper from low grade ores using bioleaching and phytomining

73
Q

Describe the process of phytomining.

A

Plants grow and absorb copper.
Burn the plant and turn it into ash.
Add acid to the ash to make a soluble copper compound.

74
Q

Describe the process of bioleaching.

A

Add bacteria to the rock and it produces a soluble copper compound

75
Q

How do we get copper from the soluble copper compound?

A

Displacement
Electrolysis

76
Q

Why do we use displacement using scrap iron to displace copper from soluble copper compound?

A

Iron is more reactive than copper.
Scrap iron is cheap.

77
Q

How does electrolysis get copper form soluble copper compound?

A

Positive copper ions are attracted to the negative cathode. Cu2+ gains 2 electrons and is reduced.
Negative ions are attracted to the positive anode. Negative ions lose electrons (oxidation)

78
Q

What is recycling?

A

Involves melting the products and then remoulding or recasting them into new products.

79
Q

How does reusing and recycling make processes more sustainable?

A

It reduces:
-the use of the Earth’s limited resources
-energy consumption and the use of fuels
-the impact of manufacturing new materials on the environment
-the impact of waste disposal on the environment

80
Q

How can you get high quality products by recycling?

A

The better the separation of the materials when they’re recycled, the higher the quality of the final material produced

81
Q

What do we look at when considering a life cycle assessment?

A

Raw Materials
Manufacture
Transport
Use
Disposal

82
Q

What is crude oil?

A

A mixture of a large number of compounds. Most of the compounds are hydrocarbons.

83
Q

What are hydrocarbons?

A

Molecules made of only hydrogen and carbon.

84
Q

What is the general formula for an alkane?

A

CnH2n+2

85
Q

What is fractional distillation?

A

Crude oil is heated until it evaporates, then it can condense at a number of different temperatures.

86
Q

Describe the process of fractional distillation.

A

Crude oil is heated an vapourised outside the column.
It’s then pumped into the column, where the gases rise to their different boiling points.
The different hydrocarbons are now condensed back into liquids and are collected.

87
Q

What are alkanes?

A

A family of saturated hydrocarbons (only contain single covalent bonds)

88
Q

What happens when alkanes experience complete combustion?

A

Carbon atoms are oxidised, combining with the oxygen to form carbon dioxide.
Hydrogen atoms in the alkane are also oxidised, combining with the oxygen to form water.

89
Q

What is cracking?

A

Long chain fractions are broken down to make shorter, more valuable and useful fractions.

90
Q

What does thermal cracking require?

A

High temperature
High pressure

91
Q

What does catalytic cracking require?

A

Low temperature
Low pressure
Zeolite catalyst

92
Q

Describe the method for cracking hydrocarbons in liquid paraffin with a catalyst.

A

Set up equipment: porcelain chips and mineral wool soaked in liquid paraffin in a boiling tube, bung on top of boiling tube leading into delivery tube which passes into a trough of water and leads up into a boiling tube full of the water.
Heat the paraffin strongly.
After a minute, collect the gas that bubbles off.
Add bromine water to the gas collected.
Alkenes decolour in the presence of bromine water.

93
Q

What is the general formula for an alkene?

A

CnH2n
(Contains a double bond between 2 carbon atoms)

94
Q

What are polymers?

A

Huge molecules made of small repeating units

95
Q

What are monomers?

A

Small molecules that make up polymers. They’re very reactive because they contain a double bond.

96
Q

What percentage of the air is nitrogen?

A

80%

97
Q

What percentage of the air is oxygen?

A

20%

GCSE Chemistry (4 decks)

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