Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > Chemical Changes > Flashcards

Chemical Changes Flashcards

1
Q

Range of pH scale

A

0 to 14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is lower on pH scale

A

More acidic solutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is higher on pH scale

A

More alkaline solutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

pH of neutral substances

A

7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do you use to measure pH of a solution

A

An indicator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Indicator

A

Dye that changes colour depending on whether it’s above or below a certain pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Wide range indicator

A

Indicator that contains a mixture of dyes so they gradually change colour over a broad range of pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Example of wide range indicator

A

Universal indicator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Colour of acidic solutions on universal indicator

A

Orange-red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Colour of alkaline solution on universal indicator

A

Blue-purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Colour of neutral solution on universal indicator

A

Green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How to measure pH electronically

A
  • pH probe and pH meter
  • probe placed in solution, meter gives numerical value of pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

More accurate method of measuring pH

A

pH probe and pH indicator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Acid

A

Substance that forms aqueous solutions with pH less than 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What ions do acids form in water

A

H⁺

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Base

A

A substance with pH greater than 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Alkali

A

Base that dissolves in water to form a solution with pH greater than 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What ions do alkalis form in water

A

OH⁻

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Neutralisation

A

Reaction between acid and base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Neutralisation reaction word equation

A

acid + base —> salt + water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Neutralisation reaction between acids and alkalis symbol equation

A

H⁺ + OH⁻ —> H₂O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens when an acid/alkali neutralise each other

A

Products will be neutral with pH 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens to strong acids in water

A
  • ionise completely
  • all acid particles dissociate to release H⁺ ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens to weak acids in water

A
  • do not fully ionise
  • small proportion of acid particles dissociate to release H⁺ ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Is ionisation of weak acids reversible

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is ionisation of weak acids reversible

A
  • reaction sets up equilibrium between undissociated and dissociated acid
    as only a few acids particles release H⁺, equalibrium position lies well to left
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which kind of acid is more reactive

A

Stronger ones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why are stronger acids more reactive

A

Higher concentration of H⁺ ions increases reactivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

pH

A

Measure of concentration of hydrogen (H⁺) ions in a solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What happens to concentration of H⁺ ions as pH decreases by 1

A

It increases by a factor of 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Formula for factor of change in H⁺ ion concentration

A

Factor H⁺ ion concentration changes by = 10⁻ˣ
X = change in pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Acid strength

A

Proportion of acid molecules that ionise in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Acid concentration

A

How much acid there is in a certain volume of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How does acid concentration affect pH

A

pH decreases as acid concentration increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Metal bases

A
  • metal oxide
  • metal hydroxide
  • metal carbonate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Do metal oxides dissolve in water

37
Q

Do metal hydroxides dissolve in water

38
Q

Acid + metal oxide —>

A

Salt + water

39
Q

Acid + metal hydroxide —>

A

Salt + water

40
Q

Acid + metal carbonate —>

A

Salt + water + carbon dioxide

41
Q

Making salts practical

A
  • pick right acid and insoluble base
  • gently warm dilute acid with Bunsen burner, turn off
  • add insoluble base to acid a bit at a time until no more reacts - base is in excess and sinks to bottom of flask after stirring as all acid has been neutralised
  • filter out excess solid to get salt solution
  • pure/solid salt crystals - gently heat solution in water bath to evaporate some water, stop, leave solution to cool, crystals form to be filtered + dried
42
Q

What is reactivity series

A

List of metals in order of reactivity towards other substances

43
Q

Reactivity series

A
  • potassium
  • sodium
  • calcium
  • magnesium
  • aluminium
  • carbon
  • zinc
  • iron
  • lead
  • tin
  • hydrogen
  • copper
  • silver
  • gold
  • platinum
44
Q

What determines reactivity of metals

A

How easily they lose electrons - forming positive ions

45
Q

What happens when metals react with water or acid

A

Lose electrons - forming positive ions

46
Q

Acid + metal —>

A

Salt + hydrogen

47
Q

What indicates speed of reaction between acid and metal

A

Rate at which bubbles of hydrogen are given off

48
Q

How to more reactive metals react

A
  • faster
  • explosively
49
Q

How do less reactive metals react

A
  • slower
  • less violently
50
Q

Metal + water —>

A

Metal hydroxide + hydrogen

51
Q

Which metals will react with water

A

More reactive ones

52
Q

Oxidation in terms of oxygen

A
  • metals reacting with oxygen to form oxides
  • gain of oxygen
53
Q

Reduction in terms of oxygen

A
  • reaction that separates a metal from it’s oxide
  • loss of oxygen
54
Q

How can some metals be extracted by reduction with carbon

A
  • metal reacted with carbon
  • ore is reduced as oxygen is removed from it
  • carbon gains oxygen and is oxidised
55
Q

Which metals are extracted by electrolysis

A

Metals above carbon on reactivity series

56
Q

Which metals are extracted by reduction using carbon

A

Metals below carbon on reactivity series

57
Q

Why are some elements mined in elemental form

A

They are so unreactive

58
Q

Oxidation in terms of electrons

A

Loss of electrons

59
Q

Reduction in terms of electrons

A

Gain of electrons

60
Q

Redox reaction

A

Reaction where reduction and oxidation happen at the same time

61
Q

Displacement reaction

A

Redox reaction where a more reactive metal displaces a less reactive metal from its compound

62
Q

Why are displacement reactions redox reactions

A
  • metal ion gains electrons - reduced
  • metal atom loses electrons 0 oxidised
63
Q

Electrolysis equipment

A
  • beaker
  • electrolyte solution
  • anode
  • cathode
  • wire + power source
64
Q

Electrolyte solution

A

Liquid/solution containing ionic compound - electrons free to move

65
Q

Electrodes

A

Solid conductors

66
Q

Anode charge

67
Q

Cathode charge

68
Q

What does electrolysis mean

A

Splitting up with electricity

69
Q

Versions of electrolysis

A
  • electrolysis of molten substance
  • electrolysis of aqueous solution
70
Q

How does electrolysis split up molten compounds

A
  • electric current flows through electrolyte
  • ions attracted to electrodes
  • ions discharged at electrodes
71
Q

What happens at anode

72
Q

What happens at cathode

73
Q

Oxidation

A
  • loss of electrons
  • gain of oxygen
74
Q

Reduction

A
  • gain of electrons
  • loss of oxygen
75
Q

Which process occurs first in electrolysis

76
Q

What happens after oxidation in electrolysis

A

Electrons travel through wire from anode to cathode for reduction

77
Q

Why is it preferable to extract metals through displacement with carbon

78
Q

When is electrolysis used to extract metals from metal oxide

A

When metal more reactive than carbon

79
Q

Downsides of electrolysis

A

Requires much energy so expensive

80
Q

Why is aluminum oxide not ready for electrolysis straight away

A
  • electrolysis needs ions free to move
  • aluminum oxide solid - ions fixed
81
Q

How to prepare aluminum oxide for electrolysis

A
  • purify bauxite into Al₂O₃
  • mix Al₂O₃ with cryolite mineral - lowers melting point
  • melt Al₂O₃ to become molten - ions free to move
82
Q

When is electrolysis of aqueous solution used

A

When substance being separated is soluble - dissolved in water (easy to do)

83
Q

What is always present from water in electrolysis of aqueous soltion

A
  • H⁺ ions
  • OH⁻ ions
84
Q

Which ions from water go to anode

85
Q

Which ions from water go to cathode

86
Q

Aqueous electrolysis rules at anode

A
  • group 7 metal - gets discharged
  • NO group 7 metal -OH⁻ gets discharged
87
Q

Aqueous electrolysis rules at cathode

A

Least reactive gets discharged

88
Q

H⁺ half equation

A

2H⁺ + 2e⁻ –> H₂

89
Q

OH⁻ half equation

A

4OH⁻ –> 2H₂O + O₂ + 4e⁻

Chemistry (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions