P1. Topic 4- Chemical Changes 🥇 Flashcards
1
Q
What is the range of the pH scale
A
0-14
2
Q
Range on pH scale for an acid
A
1-6
3
Q
Range on pH scale for an alkali
A
8-14
4
Q
pH for a neutral substance
A
7
5
Q
Examples of substances with pH 0-2
A
Car battery acid, stomach acid
6
Q
Examples of substances with pH 3
A
Vinegar, lime juice
7
Q
Examples of substances with pH of 4
A
Acid rain
8
Q
Examples of substances with pH of 5
A
Normal rain
9
Q
Examples of substances with pH of 7
A
Pure water
10
Q
Example of substances with pH of 8
A
Washing up liquid
11
Q
Example of substances with pH of 9-10
A
Pancreatic juice
12
Q
Example of substances with pH of 11
A
Soap powder
13
Q
Example of substances with pH of 12
A
Bleach
14
Q
Example of substances with pH of 13-14
A
Caustic soda
15
Q
Methods of measuring pH
A
Litmus paper
Universal indicator
pH probe
Phenolphthalein
16
Q
What type of reaction is between an acid and base
A
Neutralisation
17
Q
What is an acid
A
A substance that forms aqueous solutions with a pH of less than 7 and form H+ ions in water
18
Q
What is a base
A
A substance with a pH greater than 7
19
Q
What is an alkali base
A
A base that dissolves in water to form a solution with a pH greater than 7, also forming OH- ions
20
Q
Equation for neutralisation for acids and bases
A
Acid + base -> salt + water
21
Q
Equation for neutralisation for acids and alkali’s in terms of H+ and OH-
A
H+(aq) + OH- (aq) -> H2O (l)
22
Q
What do hydrogen and hydroxide ions react together to produce
A
Water
23
Q
What is the purpose of a titration
A
To find out the concentration of a solution
24
Q
Equipment for a titration
A
Conical flask, burette, pipette, white tile, clamp, clamp stand, phenolphthalein, acid, alkali
25
What is the purpose of the conical flask
To put the alkali and phenolphthalein in, creating a pink colour.
26
What is the purpose of the burette
Allows the acid to drop into the conical flask drop by drop
27
What is the purpose of the pipette
Accurately fills the burette with acid
28
What is the purpose of the white tile
To see the colour change more easily
29
What is the purpose of the clamp and clamp stand
To hold the apparatus in place
30
What colour is phenolphthalein in an acid
Colourless (NOT clear)
31
What colour is phenolphthalein in an alkali
Pink
32
What should you do while the acid is dripping into the alkali
Gently swirl
33
What should you do before you allow the acid to drip down
Measure the initial volume
34
Where should you measure the final volume of acid from
The meniscus, the bottom of the curve where the acid is
35
What should you do to get more accurate results
Do the titration multiple times
36
What is a concordant result
Regulates that are within 0.1 of each other
37
Why is phenolphthalein a good indicator to use in titrations
It is a single indicator
38
What calculation would you use for a titration calculation
Concentration
39
What is a strong acid
Completely dissociate to release H+ particles and ionise completely in water
40
What is a weak acid
Partially dissociate and do not fully ionise
41
What is a concentrated acid
Many acid particles in a fixed volume
42
What is a dilute acid
Few acid particles in a fixed volume
43
Acid + metal oxide -> ?
Salt + water
44
Acid + metal carbonates -> ?
Salt + water + carbon dioxide
45
Can you make soluble salts from an insoluble base?
Yes- copper sulphate
46
Describe how to make pure, dry copper sulphate crystals using copper oxide and sulphuric acid (6)
Gently heat an evaporating basin with a fixed volume of sulphuric acid in using a Bunsen burner, tripod, heatproof mat and gauze.
Transfer The acid into a beaker and add spatulas of copper oxide until it has fully reacted and solid copper oxide starts to collect at the bottom.
Filter the mixture using filter paper and a funnel to remove the excess solid copper oxide and transfer the solution back into the evaporating basin.
Heat the solution until 3/4 has evaporated and leave in a dry place to allow the remaining water to evaporate, leaving pure, dry crystals behind and finally, pat the dry crystals with filter paper or tissue.
47
What is the reactivity series
A list of metals that indicate the reactivity towards other substances, and how easily they lose electrons. The higher up the reactivity series a metal is, the more easily they form positive ions.
48
State the reactivity series
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
Platinum
49
Acid + metal -> ?
Salt+ hydrogen
50
What will happen to rate of reaction with a very reactive metal in an acid
The reaction will go faster
51
Give some observations when reacting magnesium with cold, dilute acid.
Vigorous reaction, lots of effervescence (fizzing/bubbling)
52
Metal + water -> ?
Metal hydroxide + Hydrogen
53
Name 4 elements that will react in water
Potassium, sodium, lithium, calcium
54
Name 4 metals that don’t react in water
Iron, copper, gold, silver
55
How are metals found in our natural environment
As ores, commonly in oxides
56
What is the formation of metal ore
Oxidation
57
What is the extraction of metal ore
Reduction
58
What can some metals be extracted by reduction with
Carbon
59
Why is the reactivity important when determining if something can be reduced by carbon
Only metals below carbon in the reactivity series can be extracted by reduction using carbon
60
How can we extract metals more reactive than carbon
Electrolysis
61
What does oxidation mean
Loss of electrons
62
What does reduction mean
The gain of electrons
63
What is the mnemonic for redox equations
OIL RIG
64
What does OIL RIG stand for
Oxidation is loss (of electrons) , reduction is gain (of electrons)
65
What is a displacement reaction
When a more reactive metal will displace a less reactive metal from its compound
66
What is displaced in this reaction: Mg(s) + ZnCl2(aq) -> MgCl2(aq) + Zn(s)
Zinc
67
What does Cl- represent in the follow equation: Mg(s) + Zn2+(aq) +2Cl-(aq) -> Mg2+(aq) + 2Cl-(aq) +Zn(s)
Spectator ion
68
What is being oxidised in the following equation: Mg(s) + Zn2+(aq) +2Cl-(aq) -> Mg2+(aq) + 2Cl-(aq) +Zn(s)
Magnesium
69
What is being reduced in the following equation: Mg(s) + Zn2+(aq) +2Cl-(aq) -> Mg2+(aq) + 2Cl-(aq) +Zn(s)
Zinc
70
What does electrolysis literally mean
Splitting up with electricity
71
During electrolysis, an electric current is passed through an electrolyte, what is an electrolyte
A molten or dissolved compound
72
Why must the electrolyte be molten or dissolved
So the ions can move towards the electrodes
73
What do ions become during electrolysis
Elements
74
Name the negative electrode
Cathode
75
Name the positive electrode
Anode
76
How to remember which ions go to which electrode
Cations are pawsitive so they go to the cathode, anions are onions that are negative and make you cry so they go to the anode
77
What happens to positive ions at the electrode
Reduced at the cathode
78
What happens to the negative ions at the electrode
Oxidised at the anode
79
Which electrode do metal ions go to
Cathode
80
Which electrode do non-metals go to
Anode
81
What ore does aluminium come from
Bauxite
82
What is added to aluminium ore to lower the melting point
Cryolite
83
Where do Al3+ ions go
Negative electrode
84
Where do O2- ions go
Positive electrode
85
What other molecules may be in an aqueous solution
Water
86
87
What will be produced at the cathode if H+ ions and metal ions more reactive than hydrogen are present
Hydrogen gas
88
What will be produced at the cathode if the metal ion is less reactive than hydrogen
The metal
89
What is a halide ion
A negatively charged ion formed when a halogen atom gains an electron
90
What will be produced at the anode if OH- and halide ions are present
Molecules of halogens will be formed
91
What will be produced at the anode if no halide ions are present
The OH- ion will be discharged, forming oxygen
92
What is a half equation
An equation that shows the loss or gain of electrons to form an element
93
What are the electrodes made of
Graphite
94
Why must the positive electrode be continuously replaced
Oxygen formed at the anode will react with the carbon in the graphite and will form carbon dioxide, wearing it down over time,
