Topic 4 Chemical Changes Flashcards

1
Q

What happens when metals react with water or acid?

A

Lose electrons and form positive ions

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2
Q

Which 2 non-metals are included in the reactivity series?

A

Hydrogen and carbon

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3
Q

What is the order of metals in the reactivity series?

A

Potassium
Sodium
Lithium
Calcium
Magnesium
Carbon
Zinc
Iron
Hydrogen
Copper

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4
Q

What is the order of the top 5 metals in the reactivity series?

A

Potassium
Sodium
Lithium
Calcium
Magnesium

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5
Q

What is the order of the bottom 5 metals (and nonmetals) in the reactivity series?

A

Carbon
Zinc
Iron
Hydrogen
Copper

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6
Q

How else can the pH be measured other than using universal indicator?

A

pH probe

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7
Q

What do acids produce in aqueous solutions?

A

Hydrogen ions

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8
Q

What are bases?

A

insoluble metal hydroxides and metal oxides

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9
Q

What are alkalis?

A

Soluble metal hydroxides

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10
Q

What do aqueous solutions of alkalis contain?

A

Hydroxide ions

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11
Q

What is the difference between an alkali and a base?

A

Alkalis are bases that dissolve in water to form alkaline solutions

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12
Q

What is the word equation for a neutralisation reaction?

A

Acid + base > salt + water

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13
Q

In neutralisation reactions between an acid and alkali what do hydrogen ions and hydroxide ions react to form?

A

Water

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14
Q

What are titrations used for?

A

find reacting volumes of acid and alkali solutions

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15
Q

What is pH a measure of?

A

Concentration of hydrogen ions in a solution

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16
Q

What happens to a strong acid in aqueous solution?

A

Ionised completely (all acid particles dissociate to release H+ ions)

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17
Q

What are 3 examples of strong acids?

A

Sulfuric
Hydrochloric
Nitric

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18
Q

What are 3 examples of weak acids?

A

Ethanoic
Citric
Carbonic

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19
Q

What happens to a weak acid in aqueous solution?

A

Partially ionised (small proportion of acid particles dissociate to release H+ ions)

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20
Q

What is the concentration of an acid a measure of?

A

How much acid there is in a certain volume of water

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21
Q

What is an acids strength a measure of?

A

What proportion of acid molecules ionise in water

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22
Q

What type of reaction is a metal reacting with oxygen to produce metal oxides?

A

Oxidation

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23
Q

How are most metals in the earth found?

A

As compounds

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24
Q

How are unreactive metals such as gold found in the earth?

A

As the metal itself

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25
Q

What is an ore?

A

rock that contains enough of metal or metal compound to make extracting metal worthwhile

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26
Q

How can metals less reactive than carbon be extracted from their oxides?

A

By reduction with carbon

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27
Q

How can metals higher than carbon in the reactivity series be extracted?

A

Using electrolysis

28
Q

In the reaction where a metal is extracted by reduction using carbon what is reduced?

A

ore as oxygen is removed

29
Q

In the reaction where a metal is extracted by reduction with carbon what is oxidised?

A

Carbon as it gains oxygen

30
Q

What type of reaction are displacement reactions?

A

REDOX

31
Q

In displacement reactions what is always reduced?

A

Metal ion (gains electrons)

32
Q

In displacement reactions what is always oxidised?

A

Metal atom (loses electrons)

33
Q

What does an ionic equation only show?

A

Particles that react and products they form

34
Q

What does an ionic equation for a displacement reaction only show?

A

Substances which are oxidised and reduced

35
Q

What do some metals react with acid to produce?

A

salt and hydrogen

36
Q

What is the word equation for a reaction between an acid and a metal?

A

Acid + metal > salt + hydrogen

37
Q

What is the word equation for a reaction between a metal and water?

A

Metal + water > metal hydroxide + hydrogen

38
Q

What is the word equation for a reaction between an acid and a metal carbonate?

A

Acid + metal carbonate > salt + water + carbon dioxide

39
Q

How can soluble salts be made?

A

By reacting acid with insoluble base

40
Q

What are the 3 steps to make soluble salts?

A

Add solid to acid until no more reacts
Filter out excess solid
Crystallise solution to produce solid salts

41
Q

For every decrease of 1 on the pH scale, how does this affect the concentration of H+ ions?

A

Increases by factor of 10

42
Q

What is the electrolyte?

A

Molten/dissolved ionic compound

43
Q

What is the electrode?

A

Solid that conducts electricity and is submerged in electrolyte

44
Q

What does passing an electric current through electrolytes cause?

A

Ions to move to electrodes

45
Q

Which is the negative electrode?

A

Cathode

46
Q

Where do the positive ions in the electrolyte move towards?

A

Cathode

47
Q

What happens at the cathode?

A

Positive ions gain electrons- reduced

48
Q

Which is the positive electrode?

A

Anode

49
Q

Where do the negatively charged ions in the electrolyte move towards?

A

Anode

50
Q

What happens at the anode?

A

Negative ions lose electrons- oxidised

51
Q

What happens at the electrodes?

A

Ions are discharged producing elements

52
Q

Why can molten ionic compounds be electrolysed?

A

Ions move freely and conduct electricity

53
Q

Why is extracting metals via electrolysis very expensive?

A

Lots of energy to melt compounds and produce electrical current

54
Q

Why does the anode need to be replaced regularly?

A

Made of carbon- reacts with oxygen to produce CO2

55
Q

What molten mixture is aluminium extracted from via electrolysis?

A

Aluminium oxide and cryolite

56
Q

Why is aluminium oxide mixed with cryolite (in the extraction of aluminium via electrolysis)?

A

Aluminium oxide has high melting point -to lower melting point

57
Q

What is used as the anode in the extraction of aluminium via electrolysis?

A

Carbon

58
Q

What is the chemical formula for aluminium oxide?

A

Al3O2

59
Q

What happens to the aluminium ions in electrolysis (in the extraction of aluminium)?

A

Pick up 3 electrons at cathode
Turn into neutral aluminium atoms
Sink to bottom of electrolysis tank

60
Q

What happens to the oxygen ions in electrolysis (in the extraction of aluminium)?

A

Lose 2 electrons at anode
Neutral oxygen atoms combine to form 02 molecules

61
Q

What is also present in aqueous solutions as well as ions from the ionic compound?

A

Hydrogen ions and hydroxide ions from water

62
Q

When will hydrogen gas be produced at the cathode?

A

Metal is more reactive than hydrogen

63
Q

When will hydroxide ions be discharged and oxygen produced at the anode?

A

If no halide ions present

64
Q

What are 3 halogens that could be produced at the anode?

A

Chlorine
Bromine
Iodine

65
Q

What are inert electrodes?

A

Don’t react with electrolyte

66
Q

What do half equations show?

A

Reactions at electrodes