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OCR GCSE CHEMISTRY > Paper 4 Higher > Flashcards

Paper 4 Higher Flashcards

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1
Q

Group 1 metals hardness

A

They are soft and can be cut with a knife

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2
Q

Why do group 1 elements share similar chemical properties?

A

They each have 1 outer shell electron, so they react in similar ways

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3
Q

Explain why the reactivity of the group 1 metals with dilute acids increases as you move down the group

A

Going down group 1, the outer shell electron gets further form the nucleus, so is less strongly attracted to it. This means less energy is needed to remove the outer electron, so the metals form positive ions (making them more reactive)

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4
Q

Charge of halide ion

A

1-

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5
Q

Physical appearance of iodine at room temperature

A

Dark grey crystalline solid

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6
Q

Boiling point going down group 7

A

Increases

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7
Q

Trend in reactivity down group 7

A

Decreases, because outer shell becomes further from the nucleus. So there’s less attraction and it’s harder for halogens to gain an electron

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8
Q

Describe colour change when adding drops of colourless chlorine water to colourless solution of potassium iodide

A

Solution will change from colourless to brown. The chlorine displaces the iodine, forming a brown solution of iodine.

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9
Q

Colour of group 0 noble bases

A

Colourless

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10
Q

Boiling point trend group 0

A

Increases as you go down

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11
Q

Where are transition metals on the periodic table?

A

In the centre

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12
Q

Explain why a transition metal what be a good material to make a saucepan with

A

High melting point- can withstand high cooking temperatures
Good conductor of heat- can transfer heat to the food well
Relatively unreactive- unlikely to react with chemicals in the food and degrade

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13
Q

Transition metal ions

A

They form highly coloured compounds

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14
Q

Reactive metal reacts with water

A

Vigorous reaction, with a large number of bubbles emitted in a short time

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15
Q

Test for chlorine gas

A

Put damp blue litmus paper into a sample of the gas. Chlorine will bleach the litmus paper, turning it white.

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16
Q

Test for hydrogen

A

Hold a lit splint at the end of a test tube of the gas. If hydrogen is present, you’ll hear a squeaky popping sound, as the hydrogen burns rapidly with the oxygen in the air.

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17
Q

Test for oxygen

A

Put a glowing splint into the test tube and see if it relights

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18
Q

Test for carbon dioxide

A

Limewater turns cloudy

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19
Q

Iodide (I2) halide ion colour

A

Yellow

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20
Q

Barium chloride add metal carbonate solution

A

White precipitate is formed

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21
Q

Describe the test for halides

A

Add dilute nitric acid to the solution being tested, followed by silver nitrate solution. A silver halide precipitate will form if halide ions are present. The colours of the precipitate are:
White- Chloride
Cream- Bromide
Yellow- Iodide

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22
Q

Potassium ion flame

A

Lilac

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23
Q

How do you clean a wire loop so you can use it to do a flame test?

A

Dip the loop in hydrochloric acid and then rinse it in deionised water / hold it in a blue flame from a Bunsen burner

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24
Q

Copper, Cu2+ flame colour

A

Blue-green

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25
Q

Sodium, Na+ flame colour

A

Yellow

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26
Q

Calcium, Ca+ flame colour

A

Brick red

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27
Q

Iron(III) hydroxide

A

Brown

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28
Q

Instrumental analysis

A

Analysing substances using machines

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29
Q

Advantages of instrumental analysis instead of chemical tests

A

Instrumental tests are sensitive, fast and accurate (they aren’t affected by human error)

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30
Q

What is meant by the ‘end point’ of a titration?

A

The point at which the indicator changes colour- so the point at which the alkali (or acid) has been fully neutralised.

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31
Q

What is a standard solution?

A

A solution with a known concentration

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32
Q

What’s more accurate, a Pipette or a measuring cylinder?

A

Pipettes as they are calibrated, which reduces transfer errors.

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33
Q

Explain how you can use a burette to measure the volume of acid required to neutralise an alkali

A

Fill a burette with acid, and measure the initial volume. Add acid to the alkali until the end-point is reached, and measure the final volume. Then take the initial reading away from the final reading to calculate the volume of acid you needed (the titre).

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34
Q

Why should you always pour acid (or alkali) into a burette below eye level?

A

Theres a chance you could spill some when filling the burette, so having your eyes above the level of the acid or alkali will prevent it from getting in your eyes or on your face.

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35
Q

Formula for molar volume of a gas

A

Gas volume/number of moles

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36
Q

Percentage yield

A

(Actual yield/theoretical yield) x100

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37
Q

What is atom economy?

A

The percentage of the mass of the reactants that has been converted into the desired products

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38
Q

Safety precautions when producing a harmful gas

A
  • lab coat, gloves, goggles
  • carry out the reaction in a fume cupboard to reduce the risk of inhaling the gas
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39
Q

How could you increase the surface area of a 5g block of zinc?

A

Cut the block into smaller pieces or grind it into fillings/powder

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40
Q

Describe what must happen for two particles to react together

A

The particles must collide with enough energy to react

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41
Q

Describe how a catalyst increases the rate of reaction

A

It provides an alternative reaction pathway that has a lower activation energy

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42
Q

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

A

Concentration of products is greater than concentration of reactants

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43
Q

What does increasing the temp of a reversible reaction do?

A

Move the reaction in the endothermic direction

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44
Q

What does increasing pressure of reversible reaction do?

A

Shift to the side wilt h fewer moles

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45
Q

Method used to extract iron from iron oxide

A

Reduction with carbon

46
Q

Why are some metals extracted by electrolysis instead of by reduction with carbon?

A

Metals that are more reactive than carbon cant be extracted by reduction with carbon

47
Q

Describe how electrolysis is used to extract a metal from its ore

A

The metal containing compound is melted, and an electric current is passed through it. Pure metal discharges at the cathode. A non metal, usually oxygen, forms at the anode.

48
Q

Describe how bioleaching (bacterial extraction) works.

A
  • uses bacteria to separate metal from their ores
  • solution (leachate) contains metal ions
  • extracted by displacement or electrolysis
49
Q

Describe how phytoextraction works

A

Phytoextraction involves growing plants in soil that contains metal compounds. The plants absorb the metal compounds, so the metal gradually builds up in the leaves of the plants. The plants can be harvested, dried and burned in a furnace. The ash contains soluble metal compounds from which the metal can be extracted by displacement or electrolysis.

50
Q

Suggest a reason why scientists might want to investigate biological extraction methods

A
  • the supply of some metal ores is limited
  • the demand for metals is growing
  • traditional mining methods are damaging to the environment
51
Q

Give a disadvantage of using biological methods to extract metals

A

They are very slow

52
Q

Alloy

A

A mixture of two or more different metals, or a metal and non metal

53
Q

What is bronze made of?

A

Copper and tin

54
Q

Name given to the alloy formed from copper and zinc

A

Brass

55
Q

Why is duralumin is used to make aeroplanes instead of pure aluminium?

A
  • it has a low density, so it’s really light
  • it is stronger than aluminium so it is less likely to be damaged
56
Q

Solder is an alloy of which two metals

A

Lead and tin

57
Q

Why is solder suitable for connecting components in electronic circuits?

A
  • doesn’t have a definite melting point
  • gradually solidifies as it cools down, meaning it can be easily worked
  • it’s melting point is relatively low, so it can be used without causing damage toi other components in the circuit
  • conducts electricity
58
Q

What is corrosion?

A

The process of which something is slowly damaged or destroyed by a chemical process

59
Q

What reaction occurs during the rusting of iron?

A

Oxidation

60
Q

3 main essential elements in fertilisers

A

Nitrogen, potassium and phosphorus

61
Q

How to produce ammonium sulfate in the lab

A
  • add a few drops of methyl orange indicator to an ammonia solution
  • use a titration method to add sulfuric acid (from a burette) to the ammonia solution until it changes colour…
  • from yellow to red
  • to get pure salt crystals, repeat the titration without the indicator…
  • adding exactly as much sulfuric acid as was required to neutralise the ammonia before
  • finally, crystallise the solution, filter out the crystals and leave them to dry
62
Q

Give an example of how a factory might produce a fertiliser using integrated processses

A

They might make ammonia using the haber process, and sulfuric acid using the contact process. They can be used to make ammonium sulfate.

63
Q

Why might the rate of reaction affect the profitability of an industrial process?

A

Products made at a faster rate may be more profitable as you can produce more of them

64
Q

What is the purpose of a life cycle assessment (LCA)?

A

To work out the environmental impact of each stage of the life of a product

65
Q

4 stages of LCA

A
  • choice of raw material
  • manufacture
  • product use
  • disposal
66
Q

Suggest two factors that should be considered when assessing g the manufacturing stage in the life cycle of a product

A
  • the energy input needed to make the product, the potential for air pollution and production of harmful fumes
  • the disposal of water and waste products and the products recyclability
67
Q

Two issues associated with using landfill to dispose of products

A

Landfill sites take up space and can pollute land and water

68
Q

Why is making lightbulbs out of glass suitable?

A
  • glass is transparent so light can pass through it
  • has sufficiently high melting point
  • glass is brittle and can easily break but this is okay as a lightbulb isn’t often handled
69
Q

Example of a composite material

A

Carbon fibre

70
Q

Why are many hockey sticks made from synthetic composite materials rather than wood

A

Synthetic composites can be much stronger and lighter than wood

71
Q

Why is concrete suitable to build pavements?

A

It has a high compressive strength

72
Q

Definition of homologous series

A

A group of chemicals that have similar chemical structures

73
Q

Molecular formula of alkanes

A

CnH2n+2

74
Q

Complete combustion of an hydrocarbons

A

Always produces carbon dioxide and water only

75
Q

First four alkenes

A

Ethene, propene, butene and pentene

76
Q

Alkene general formula

A

CnH2n

77
Q

What happens when an alkene reacts with hydrogen?

A

The hydrogen reacts with the double bonded carbons and adds across the double bond. The double bond becomes C-C single bond.

78
Q

What does it mean if the bromine water goes from orange to colourless?

A

An alkene must have reacted with it. They react in an addition reaction, bromine is added across the double bond.

79
Q

Functional groups in alcohols

A

OH

80
Q

Alcohol general formula

A

CnH2n+1OH

81
Q

Describe what would happen if potassium manganate, KMnO4 was added to ethanol

A

Alcohols can be oxidised to produce carboxylic acids. So the ethanol will be oxidised to form ethanoic acid. As the reaction takes place, the colour of the reaction mixture changes from purple to colourless.

82
Q

Butanoic acid general formula

A

C3H7COOH

83
Q

What functional group must monomers contain in order to join together to form an addition polymer?

A

A carbon-carbon double covalent bond

84
Q

Give an example of a small molecule that is lost during a condensation polymerisation reaction

A

Water

85
Q

What type of condensation polymer is formed when monomers containing two -COOH groups react with monomers containing two -NH2 groups?

A

A polyamide

86
Q

What are proteins made from?

A

Amino acids

87
Q

Describe how you can make nylon using diaminohexane and hexanedioyl dichloride

A

In a beaker mix diaminohexane in water. In another beaker, mix hexanedioyl dichloride in an organic solvent. Pour one solution on top of the other to form two layers. Extract nylon from where the two layers meet by lifting it out the beaker with tweezers.

88
Q

What a fraction?

A

A mixture of hydrocarbons, mainly alkanes, that have similar boiling points

89
Q

What happens on a molecular level when a hydrocarbon boils?

A

The intermolecular forces of attraction between the molecules are broken

90
Q

Name two types of molecules produced during cracking?

A

Alkanes and alkenes

91
Q

Conditions for cracking

A
  • aluminium oxide catalyst
  • 400 to 700 degrees Celsius
  • 70 atm pressure
92
Q

What is a fuel cell?

A

A chemical cell which uses the reaction between a fuel and oxygen to produce a voltage

93
Q

At what point does a chemical cell stop producing a p.d?

A

When all of one of the reactants has been used up

94
Q

Give the equation for the overall reaction that takes place in a hydrogen-oxygen fuel cell

A

2H2 + O2 -> 2H2O

95
Q

Give one advantage of using a hydrogen-oxygen fuel cell instead of a petrol engine to power a car

A
  • doesn’t generate any pollutants because only product is water
  • more efficient
96
Q

Which gas makes up the largest proportion of the earths atmosphere today?

A

Nitrogen- 78%

97
Q

Where may have lots of the carbon dioxide in the early atmosphere came from?

A

Volcanic eruptions

98
Q

Suggest two reasons why the level of CO2 in the atmosphere decreased over time

A
  • it may have dissolved in the oceans
  • plants and algae may gave absorbed it during photosynthesis
99
Q

Explain the change in oxygen concentration during the evolution of the atmosphere

A

Initially, there was little or no oxygen in the atmosphere. The green plants evolved over most of the earth. As these organisms photosynthesised, they produced oxygen and removed co2. Oxygen levels gradually built up.

100
Q

Describe two ways in which nitrogen was put into the atmosphere

A
  • formed by ammonia reacting with oxygen
  • released by denitrifying bacteria
101
Q

What do greenhouse gases absorb and reflect?

A

They absorb infrared radiation and reflect some radiation back to earth

102
Q

How does the greenhouse effect work?

A
  • greenhouse gases absorb the infrared radiation that is radiated by the earth and re-emit it in all directions
  • including back towards the earth
  • infrared radiation is heat radiation so this warms the surface of the planet
103
Q

Suggest how industrialisation of more countries has affected the amount of carbon dioxide in the atmosphere

A
  • the average energy demand per person has increased
  • much of this energy comes from burning fossil fuels
  • which increases the amount of CO2 released into the atmosphere
104
Q

Explain the effect of increasing concentrations of greenhouse gases in the atmosphere

A

The greenhouse effect is enhanced- more heat radiation from the earth is absorbed and less is re-emitted into space causing the atmosphere to heat up

105
Q

Explain why an increase in global temperatures could affect sea levels

A

It could lead to polar ice caps melting which could cause sea levels to rise

106
Q

Negative effect of particulate carbon in the atmosphere

A
  • can make buildings look dirty, reduce air quality and can cause respiratory problems
107
Q

How does burning fossil fuels lead to the production of nitrogen oxides?

A

Nitrogen oxides are produced by the reaction between oxygen and nitrogen in the air, caused by high temperatures when fuels burn

108
Q

How does burning fossil fuels produce sulfur dioxide?

A

Sulfur dioxide is released when fossil fuels containing sulfur impurities are burned

109
Q

A student tests for chloride ions

She adds dilute nitric acid to the solution. She then adds a few drops of silver nitrate solution. Why does she need to add dilute nitric acid in this test?

A

To make sure no carbonate ions are present

110
Q

What is the greenhouse effect caused by?

A

The infrared radiation being absorbed and re emitted by greenhouse gases

111
Q

How can we lower carbon dioxide levels?

A
  • reduce consumption of fossil fuels
  • use biofuels
  • use renewable energy sources

OCR GCSE CHEMISTRY (6 decks)

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