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GCSE Chemistry > Chemical Changes > Flashcards

Chemical Changes Flashcards

1
Q

What is produced when a metal reacts with oxygen?

A

Metal oxide

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2
Q

What is oxidation?

A

Gain of oxygen

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3
Q

What is reduction?

A

Loss of oxygen

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4
Q

What is the reactivity series?

A

Metals arranged in the order of their reactivity

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5
Q

How are metals ordered in the reactivity series?

A

The tendency of the metal to lose electrons and form positive ions

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6
Q

What is the order of metals in the reactivity series?

A

Potassium, sodium, lithium, magnesium, zinc, iron and copper

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7
Q

What experiments can be done to metals in the reactivity series?

A

How they react with water and acids

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8
Q

Why would you not use acids to predict the reactivity of sodium and potassium?

A

As they are very reactive, and it will be too dangerous

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9
Q

What are the products when a metal reacts with water?

A

Metal hydroxide and hydrogen

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10
Q

What are the products when a metal reacts with acid?

A

salt and hydrogen

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11
Q

What two nonmetals are placed in the reactivity series

A

Carbon and hydrogen

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12
Q

What is a displacement reaction?

A

When a more reactive metal can displace a less reactive metal from a compound

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13
Q

How are unreactive native metals found in the earth

A

As a metal itself

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14
Q

How are the metals that are less reactive than carbon extracted from their oxides?

A

Using carbon

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15
Q

How are metals, which are more reactive than carbon extracted from their oxides

A

By electrolysis

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16
Q

What is oxidation in terms of electron?

A

Loss of electrons

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17
Q

What is a reduction in terms of electrons?

A

Gaining of electrons

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18
Q

What is a redox reaction?

A

Reduction and oxidation occurring

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19
Q

What is an oxidising agent?

A

A substance that causes another metal to gain oxygen

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20
Q

What is a reducing agent?

A

A substance that causes another chemical to lose oxygen

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21
Q

What is the pH scale?

A

A scale of how acidic or alkaline a substance is

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22
Q

What are pH acids?

A

Less than seven

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23
Q

What pH are alkalis?

A

More than seven

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24
Q

What pH is neutral?

A

Seven

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25
Q

What can be used to measure pH?

A

universal indicator or a pH probe

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26
Q

What is a base?

A

A metal oxide

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27
Q

What is an alkali?

A

A base that is soluble typically metal hydroxides

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28
Q

What ion is in all acids?

A

H+ (hydrogen ion)

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29
Q

What ion is in all alkalis?

A

OH- (hydroxide ions)

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30
Q

What type of reaction occurs between acid and an alkali?

A

Neutralisation

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31
Q

What is the general equation for neutralisation?

A

Acid + alkali -> salt + water
Or
Acid+ base - > salt + water

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32
Q

What is the ionic equation for neutralisation?

A

H+ (aq) + OH- (aq) → H2O (l)

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33
Q

What is made when an acid reacts with an alkali/base?

A

Salt and water

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34
Q

What is made when a metal carbonate reacts with acid?

A

Salt, water and carbon dioxide

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35
Q

What is the formula for hydrochloric acid?

A

HCl

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36
Q

What is the formula for sulphuric acid?

A

H2SO4

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37
Q

What is the formula for nitric acid?

A

HNO3

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38
Q

What salt is made from hydrochloric acid?

A

Chloride

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39
Q

What else is made from sulphuric acid?

A

Sulphate

40
Q

What salt is made from nitric acid?

A

Nitrate

41
Q

How can you make a soluble salt?

A

By reacting a metal, metal hydroxide or metal oxide with an acid

42
Q

How can you make sure all of the acid is used up when making a soluble salt?

A

Keep adding the metal etc. until no more reacts

43
Q

How can you remove the metal/metal oxide or metal hydroxide when making a soluble salt?

A

Filter it off

44
Q

What is the process called when a solid salt is obtained from a salt solution

A

Crystallisation

45
Q

What is a strong acid

A

An acid that is completely ionised in an aqueous solution

46
Q

What is a weak acid?

A

An acid that is only partially ionised in aqueous solution

47
Q

What does a change in pH of one unit mean?

A

The hydrogen ion concentration of the solution has changed by a factor of 10

48
Q

What is electrolysis?

A

The breakdown of a compound back to its elements, using electricity

49
Q

What must compounds be for electrolysis to work?

A

Molten or in a solution

50
Q

Why must a compound be melted or in solution for electrolysis to work?

A

So that ions are free to move

51
Q

What is a solution called that can conduct electricity

A

Electrolyte

52
Q

What are positive ions called

A

Cations

53
Q

What are negative ions called

A

Anions

54
Q

What is the positive electrode called?

A

Anode

55
Q

What is the negative electrode called?

A

Cathode

56
Q

What does PANIC stand for?

A

Positive anode negative is cathode

57
Q

What are electrodes normally made from?

A

Graphite as it conducts electricity

58
Q

What do opposite charges do?

A

Attract

59
Q

What is electrode to positive ions move to?

A

Cathode

60
Q

What electrode do the negative ions move to?

A

Anode

61
Q

What electrode does metal form at?

A

Cathode

62
Q

What is electrode do nonmetals form at?

A

Anode

63
Q

What is electrode does hydrogen form at?

A

Cathode as hydrogen ions are positive

64
Q

What is formed at each electrode for molten potassium, bromide

A

Potassium at the negative electrode
bromine at the positive electrode

65
Q

What happens to positive ions at the cathode in terms of electrons?

A

Gaining of electrons: reduction

66
Q

What happens to negative ions at the anode in terms of electrons

A

Loss of electrons: oxidation

67
Q

What does OILRIG STAND FOR?

A

Oxidation is losing
reduction is gaining

68
Q

Why is extracting a metal using electrolysis expensive?

A

Use as large amounts of energy to melt the compound, and for the electrical current

69
Q

What is the ore aluminium is extracted from

A

Aluminium oxide (bauxite)

70
Q

What is added to aluminium oxide when it is extracted using electrolysis?

A

Cryolite

71
Q

Why is cryolite added to aluminium oxide when it is extracted using electrolysis?

A

To lower, the melting point, so reduces energy costs

72
Q

What are the electrodes made from in the electrolysis of aluminium oxide?

A

Carbon/graphite

73
Q

Why do carbon electrodes need replacing often in the electrolysis of aluminium oxide?

A

The oxygen produced reacts with the carbon electrodes to make carbon dioxide, so they were away

74
Q

What is an equation to show how the carbon electrodes wear away in the electrolysis of aluminium oxide

A

Carbon + oxygen → carbon dioxide
(C + O2 → CO2

75
Q

What is electrode does aluminium form at during electrolysis?

A

Negative cathodes as aluminium is positively charged

76
Q

What is electrode does oxygen form at during electrolysis of aluminium oxide?

A

Positive anode as oxide is negatively charged

77
Q

What is the half equation for the formation of aluminium?

A

Al3+ + 3e- → Al

Reduction is gained electrons

78
Q

What is the half equation for the formation of oxygen?

A

2O2- → O2 + 4e-

Oxidation is lost electrons

79
Q

What is a substance is formed at the electrode depend upon in aqueous solutions

A

Positive electrode: if hailide has his present, it goes to the electrodes, otherwise, oxygen always forms

Negative electrode: least reactive positive ion goes to the electrode

80
Q

What is formed at each electrode for aqueous potassium bromide?

A

Hydrogen at the negative electrode : cathode as is less reactive than potassium

Bromine at the positive electrode, as is a halide

81
Q

What is produced at the cathode if the metal is more reactive than hydrogen

A

Hydrogen

82
Q

What is produced at the anode in an aqueous solution

A

Oxygen, unless the solution contains halide ions, which then the halogen is produced

83
Q

Why does hydrogen produced when an aqueous solution is electrolysed?

A

Water molecules breakdown into hydrogen ions and hydroxide ions

84
Q

what always happens at the cathode

A

Gain of electrons so reduction

85
Q

What always happens at the anode

A

Loss of electrons, so oxidation

86
Q

Write a half equation for the reduction of copper ions

A

Cu2+ + 2e- → Cu

87
Q

Write a half equation for the oxidation of chloride ions

A

2Cl- → Cl2 + 2e-

88
Q

Write a half equation for the oxidation of oxide ions

A

2O2- → O2 + 4e-

89
Q

Write a half equation for the reduction of hydrogen ions

A

2H+ + 2e- → H2

90
Q

What technique can be used to measure the volumes of acids and other alkalis that reacts with each other?

A

Titrations

91
Q

How do you know when the neutralisation point has been met?

A

Use an indicator. This will change the colour of the neutralisation point

92
Q

What piece of equipment is used to measure the variable volume?

A

Burette

93
Q

What piece of equipment is used to measure the fixed volume?

A

Pipette

94
Q

How do you workout the mass in grams given the volume of a solution and concentration in mol/dm3

A

Workout moles, using concentration and volume (ensure volume is in dm3)

Rearrange moles, mass and Mr equation, so masses function on imput numbers

95
Q

How to make out the concentration from a set of titration results

A

R ) 1. You are very likely to be given a set of results where you need to calculate the mean titre (excluding anomalies)

  1. Using the concentration and mean titre volume work out the number of moles
  2. Use the balance equation and ratio to work out the number of moles for the concentration you are trying to work out.

Using the moles and volume (will be a fixed volume usually around 25 cm³) in the question, workout the concentration

GCSE Chemistry (8 decks)

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