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Chemistry > Chemical Changes > Flashcards

Chemical Changes Flashcards

1
Q

What is produced when a metal reacts with water?

A

Metal hydroxide and hydrogen

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2
Q

What is produced when a metal reacts with an acid?

A

Salt and hydrogen

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3
Q

What is oxidation?

A

Gain of oxygen

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4
Q

What is reduction?

A

Loss of oxygen

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5
Q

What is the reactivity series?

A

Metals arranged in order of their reactivity

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6
Q

What is the order of the metals in the reactivity series? (Please send lions monkeys zebras into cages)

A

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

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7
Q

What experiments can be done to put metals in their 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 its very reactive so it would be too dangerous

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9
Q

What two non-metals are placed in the reactivity series?

A

Carbon and hydrogen

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10
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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11
Q

How are unreactive (native) metals found in the earth?

A

As the metal itself

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12
Q

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

A

Using carbon

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13
Q

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

A

By electrolysis

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14
Q

What is oxidation in terms of electrons?

A

Loss of electrons

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15
Q

What is reduction in terms of electrons?

A

Gain of electrons

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16
Q

What is a redox reaction?

A

Reduction and oxidation occurring

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17
Q

What is an oxidising agent?

A

A substance that causes another chemical to gain oxygen

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18
Q

What is a reducing agent?

A

A substance that causes another chemical to lose oxygen

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19
Q

What is the pH scale?

A

A scale of how acidic or alkaline a substance is

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20
Q

What pH are acids?

A

Less than 7 (red/orange/yellow)

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21
Q

What pH are alkalis?

A

More than 7 (blue/purple)

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22
Q

What pH is neutral?

A

7 (green)

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23
Q

What can be used to measure pH?

A

Universal indicator or a pH probe

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24
Q

What is a base?

A

A metal oxide

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25
Q

What is an alkali?

A

A metal hydroxide, a base that is soluble (e.g. Na2O can dissolve to make NaOH)

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26
Q

What ion is in all acids?

A

H⁺ (hydrogen ion)

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27
Q

What ion is in all alkalis?

A

OH⁻ (hydroxide ions)

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28
Q

What type of reaction occurs between an acid and an alkali?

A

Neutralisation

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29
Q

What is the general equation for neutralisation?

A

Acid + alkali → salt + water

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30
Q

What is the ionic equation for neutralisation?

A

H⁺(aq) + OH⁻(aq) → H₂O(l)

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31
Q

What is made when an acid reacts with an alkali?

A

Salt and water

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32
Q

What is made when a metal carbonate reacts with an acid?

A

Salt, water, and carbon dioxide

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33
Q

What is the formula for hydrochloric acid?

A

HCl

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34
Q

What is the formula of sulphuric acid?

A

H₂SO₄

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35
Q

What is the formula of nitric acid?

A

HNO₃

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36
Q

What salt is made from hydrochloric acid?

37
Q

What salt is made from sulphuric acid?

38
Q

What salt is made from nitric acid?

39
Q

How can you make a soluble salt?

A

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

40
Q

What should you do when making a soluble salt?

A

Keep adding the metal until no more reacts

41
Q

What do you do with the unreacted metal/metal hydroxide when making a soluble salt?

A

Filter it off

42
Q

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

A

Crystallisation

43
Q

What is a strong acid?

A

An acid that is completely ionised in aqueous solution (e.g. Hydrochloric and nitric)

44
Q

What is a weak acid?

A

An acid that is only partially ionised in aqueous solution (e.g. Ethanoic, citric, carbonic)

45
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

46
Q

What is electrolysis?

A

The breakdown of a compound back to its elements using electricity

47
Q

What must compounds be for electrolysis to work?

A

Molten (melted) or in solution

48
Q

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

A

So that the ions are free to move

49
Q

What is a solution called that can conduct electricity?

A

Electrolyte

50
Q

What are positive ions called?

51
Q

What are negative ions called?

52
Q

What is the positive electrode called?

53
Q

What is the negative electrode called?

54
Q

What does PANIC stand for?

A

Positive anode, negative is the cathode

55
Q

What are electrodes normally made from?

A

Graphite (carbon) as it conducts electricity

56
Q

What do opposite charges do?

57
Q

What electrode do positive ions (cations) move to?

A

Negative (cathode)

58
Q

What electrode do negative ions (anions) move to?

A

Positive (anode)

59
Q

What electrode do metals form at?

A

Cathode (as metals form positive ions)

60
Q

What electrode do non-metals form at?

A

Anode (as non-metals form negative ions)

61
Q

What electrode does hydrogen form at?

A

Cathode as hydrogen ions are positive

62
Q

What is formed at each electrode for molten potassium bromide?

A

Potassium at the negative electrode (cathode), bromine at the positive electrode (anode)

63
Q

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

A

Gain electrons (reduction)

64
Q

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

A

Lose electrons (oxidation)

65
Q

What does OILRIG stand for?

A

Oxidation is loss, reduction is gain of electrons

66
Q

What is produced when a metal reacts with oxygen?

A

Metal oxide

67
Q

How are metals ordered in the reactivity series?

A

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

68
Q

why is extracting a metal using electrolysis expensive?

A

Uses large amounts of energy to melt the compound and for the electrical current

69
Q

What is the ore aluminium extracted from

A

Aluminium oxide (bauxite)

70
Q

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

71
Q

Why is cryolite added to aluminium oxide when its 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 the carbon electrodes need replacing often in the electrolysis of aluminium oxide?

A

The oxygen produced reacts with the carbons electrodes to make carbon dioxide so they wear away

74
Q

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

A

Carbon + oxygen —> carbon dioxide

75
Q

What electrode does aluminium form at during electrolysis

A

Negative (cathode) as aluminium is positively charged

76
Q

What 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 do the substances formed at the electrode depend upon in aqueous solutions

A

Their reactivity (the less reactive ion goes to the the electrode)

80
Q

What is formed at each electrode for aqueous potassium bromide (dissolved in water)

A

Hydrogen at the negative electrode (cathode) as its less reactive than potassium,bromine at the positive electrode (anode)

81
Q

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

82
Q

What is produced at the anode in an aqueous solution

A

Oxygen unless the solution contains halide ions when the halogen is produced

83
Q

Why does hydrogen get produced when an aqueous solution is electrolysed

A

Water molecules break down into hydrogen ions and hydroxide ions

84
Q

What always happens at the negative (cathode) electrode

A

Gain of electrons so reduction

85
Q

What always happens at the positive (anode) electrode

A

Loss of electrons so oxidation

86
Q

Write the half equation for the reduction of copper ions

A

Cu2+ + 2e- → Cu

87
Q

Write the half equation for the oxidation of chloride ions

A

2Cl- → Cl2 + 2e-

88
Q

Write the half equation for the oxidation of oxide ions

A

2O2- → O2 + 4e-

89
Q

Write the half equation for the reduction of hydrogen ions

A

2H+ + 2e- → H2

Chemistry (12 decks)

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