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Chemical Changes Flashcards

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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
What is an alkali?
A metal hydroxide, a base that is soluble (e.g. Na2O can dissolve to make NaOH)
26
What ion is in all acids?
H⁺ (hydrogen ion)
27
What ion is in all alkalis?
OH⁻ (hydroxide ions)
28
What type of reaction occurs between an acid and an alkali?
Neutralisation
29
What is the general equation for neutralisation?
Acid + alkali → salt + water
30
What is the ionic equation for neutralisation?
H⁺(aq) + OH⁻(aq) → H₂O(l)
31
What is made when an acid reacts with an alkali?
Salt and water
32
What is made when a metal carbonate reacts with an acid?
Salt, water, and carbon dioxide
33
What is the formula for hydrochloric acid?
HCl
34
What is the formula of sulphuric acid?
H₂SO₄
35
What is the formula of nitric acid?
HNO₃
36
What salt is made from hydrochloric acid?
Chloride
37
What salt is made from sulphuric acid?
Sulphate
38
What salt is made from nitric acid?
Nitrate
39
How can you make a soluble salt?
By reacting a metal, metal hydroxide or metal oxide with an acid
40
What should you do when making a soluble salt?
Keep adding the metal until no more reacts
41
What do you do with the unreacted metal/metal hydroxide when making a soluble salt?
Filter it off
42
What is the process called when a solid salt is obtained from a salt solution?
Crystallisation
43
What is a strong acid?
An acid that is completely ionised in aqueous solution (e.g. Hydrochloric and nitric)
44
What is a weak acid?
An acid that is only partially ionised in aqueous solution (e.g. Ethanoic, citric, carbonic)
45
What does a change in pH of one unit mean?
The hydrogen ion concentration of the solution has changed by a factor of 10
46
What is electrolysis?
The breakdown of a compound back to its elements using electricity
47
What must compounds be for electrolysis to work?
Molten (melted) or in solution
48
Why must a compound be melted or in solution for electrolysis to work?
So that the ions are free to move
49
What is a solution called that can conduct electricity?
Electrolyte
50
What are positive ions called?
Cations
51
What are negative ions called?
Anions
52
What is the positive electrode called?
Anode
53
What is the negative electrode called?
Cathode
54
What does PANIC stand for?
Positive anode, negative is the cathode
55
What are electrodes normally made from?
Graphite (carbon) as it conducts electricity
56
What do opposite charges do?
Attract
57
What electrode do positive ions (cations) move to?
Negative (cathode)
58
What electrode do negative ions (anions) move to?
Positive (anode)
59
What electrode do metals form at?
Cathode (as metals form positive ions)
60
What electrode do non-metals form at?
Anode (as non-metals form negative ions)
61
What electrode does hydrogen form at?
Cathode as hydrogen ions are positive
62
What is formed at each electrode for molten potassium bromide?
Potassium at the negative electrode (cathode), bromine at the positive electrode (anode)
63
What happens to positive ions at the cathode in terms of electrons?
Gain electrons (reduction)
64
What happens to negative ions at the anode in terms of electrons?
Lose electrons (oxidation)
65
What does OILRIG stand for?
Oxidation is loss, reduction is gain of electrons
66
What is produced when a metal reacts with oxygen?
Metal oxide
67
How are metals ordered in the reactivity series?
The tendency of the metal to lose electrons and form positive ions
68
why is extracting a metal using electrolysis expensive?
Uses large amounts of energy to melt the compound and for the electrical current
69
What is the ore aluminium extracted from
Aluminium oxide (bauxite)
70
What is added to aluminium oxide when it is extracted using electrolysis
Cryolite
71
Why is cryolite added to aluminium oxide when its extracted using electrolysis
To lower the melting point so reduces energy costs
72
What are the electrodes made from in the electrolysis of aluminium oxide
Carbon (graphite)
73
Why do the carbon electrodes need replacing often in the electrolysis of aluminium oxide?
The oxygen produced reacts with the carbons electrodes to make carbon dioxide so they wear away
74
What is the equation to show how the carbon electrodes wear away in the electrolysis of aluminium oxide
Carbon + oxygen —> carbon dioxide
75
What electrode does aluminium form at during electrolysis
Negative (cathode) as aluminium is positively charged
76
What electrode does oxygen form at during electrolysis of aluminium oxide
Positive (anode) as oxide is negatively charged
77
What is the half equation for the formation of aluminium
Al3+ + 3e- → Al (reduction is gained electrons)
78
What is the half equation for the formation of oxygen
2O2- → O2 + 4e- (oxidation is lost electrons)
79
What do the substances formed at the electrode depend upon in aqueous solutions
Their reactivity (the less reactive ion goes to the the electrode)
80
What is formed at each electrode for aqueous potassium bromide (dissolved in water)
Hydrogen at the negative electrode (cathode) as its less reactive than potassium,bromine at the positive electrode (anode)
81
What is produced at the cathode if the metal is more reactive than hydrogen
Hydrogen
82
What is produced at the anode in an aqueous solution
Oxygen unless the solution contains halide ions when the halogen is produced
83
Why does hydrogen get produced when an aqueous solution is electrolysed
Water molecules break down into hydrogen ions and hydroxide ions
84
What always happens at the negative (cathode) electrode
Gain of electrons so reduction
85
What always happens at the positive (anode) electrode
Loss of electrons so oxidation
86
Write the half equation for the reduction of copper ions
Cu2+ + 2e- → Cu
87
Write the half equation for the oxidation of chloride ions
2Cl- → Cl2 + 2e-
88
Write the half equation for the oxidation of oxide ions
2O2- → O2 + 4e-
89
Write the half equation for the reduction of hydrogen ions
2H+ + 2e- → H2
90
What is a halide ion?
Negatively charged particles made when halogens gain an electron e.g. fluorine

Chemistry (14 decks)

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