Chemical Changes Flashcards
1
Q
What is produced when a metal reacts with oxygen?
A
Metal oxide
2
Q
What is oxidation?
A
Gain of oxygen
3
Q
What is reduction?
A
Loss of oxygen
4
Q
What is the reactivity series?
A
Metals arranged in the order of their reactivity
5
Q
How are metals ordered in the reactivity series?
A
The tendency of the metal to lose electrons and form positive ions
6
Q
What is the order of metals in the reactivity series?
A
Potassium, sodium, lithium, magnesium, zinc, iron and copper
7
Q
What experiments can be done to metals in the reactivity series?
A
How they react with water and acids
8
Q
Why would you not use acids to predict the reactivity of sodium and potassium?
A
As they are very reactive, and it will be too dangerous
9
Q
What are the products when a metal reacts with water?
A
Metal hydroxide and hydrogen
10
Q
What are the products when a metal reacts with acid?
A
salt and hydrogen
11
Q
What two nonmetals are placed in the reactivity series
A
Carbon and hydrogen
12
Q
What is a displacement reaction?
A
When a more reactive metal can displace a less reactive metal from a compound
13
Q
How are unreactive native metals found in the earth
A
As a metal itself
14
Q
How are the metals that are less reactive than carbon extracted from their oxides?
A
Using carbon
15
Q
How are metals, which are more reactive than carbon extracted from their oxides
A
By electrolysis
16
Q
What is oxidation in terms of electron?
A
Loss of electrons
17
Q
What is a reduction in terms of electrons?
A
Gaining of electrons
18
Q
What is a redox reaction?
A
Reduction and oxidation occurring
19
Q
What is an oxidising agent?
A
A substance that causes another metal to gain oxygen
20
Q
What is a reducing agent?
A
A substance that causes another chemical to lose oxygen
21
Q
What is the pH scale?
A
A scale of how acidic or alkaline a substance is
22
Q
What are pH acids?
A
Less than seven
23
Q
What pH are alkalis?
A
More than seven
24
Q
What pH is neutral?
A
Seven
25
What can be used to measure pH?
universal indicator or a pH probe
26
What is a base?
A metal oxide
27
What is an alkali?
A base that is soluble typically metal hydroxides
28
What ion is in all acids?
H+ (hydrogen ion)
29
What ion is in all alkalis?
OH- (hydroxide ions)
30
What type of reaction occurs between acid and an alkali?
Neutralisation
31
What is the general equation for neutralisation?
Acid + alkali -> salt + water
Or
Acid+ base - > salt + water
32
What is the ionic equation for neutralisation?
H+ (aq) + OH- (aq) → H2O (l)
33
What is made when an acid reacts with an alkali/base?
Salt and water
34
What is made when a metal carbonate reacts with acid?
Salt, water and carbon dioxide
35
What is the formula for hydrochloric acid?
HCl
36
What is the formula for sulphuric acid?
H2SO4
37
What is the formula for nitric acid?
HNO3
38
What salt is made from hydrochloric acid?
Chloride
39
What else is made from sulphuric acid?
Sulphate
40
What salt is made from nitric acid?
Nitrate
41
How can you make a soluble salt?
By reacting a metal, metal hydroxide or metal oxide with an acid
42
How can you make sure all of the acid is used up when making a soluble salt?
Keep adding the metal etc. until no more reacts
43
How can you remove the metal/metal oxide or metal hydroxide when making a soluble salt?
Filter it off
44
What is the process called when a solid salt is obtained from a salt solution
Crystallisation
45
What is a strong acid
An acid that is completely ionised in an aqueous solution
46
What is a weak acid?
An acid that is only partially ionised in aqueous solution
47
What does a change in pH of one unit mean?
The hydrogen ion concentration of the solution has changed by a factor of 10
48
What is electrolysis?
The breakdown of a compound back to its elements, using electricity
49
What must compounds be for electrolysis to work?
Molten or in a solution
50
Why must a compound be melted or in solution for electrolysis to work?
So that ions are free to move
51
What is a solution called that can conduct electricity
Electrolyte
52
What are positive ions called
Cations
53
What are negative ions called
Anions
54
What is the positive electrode called?
Anode
55
What is the negative electrode called?
Cathode
56
What does PANIC stand for?
Positive anode negative is cathode
57
What are electrodes normally made from?
Graphite as it conducts electricity
58
What do opposite charges do?
Attract
59
What is electrode to positive ions move to?
Cathode
60
What electrode do the negative ions move to?
Anode
61
What electrode does metal form at?
Cathode
62
What is electrode do nonmetals form at?
Anode
63
What is electrode does hydrogen form at?
Cathode as hydrogen ions are positive
64
What is formed at each electrode for molten potassium, bromide
Potassium at the negative electrode
bromine at the positive electrode
65
What happens to positive ions at the cathode in terms of electrons?
Gaining of electrons: reduction
66
What happens to negative ions at the anode in terms of electrons
Loss of electrons: oxidation
67
What does OILRIG STAND FOR?
Oxidation is losing
reduction is gaining
68
Why is extracting a metal using electrolysis expensive?
Use as large amounts of energy to melt the compound, and for the electrical current
69
What is the ore aluminium is 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 it is 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 carbon electrodes need replacing often in the electrolysis of aluminium oxide?
The oxygen produced reacts with the carbon electrodes to make carbon dioxide, so they were away
74
What is an equation to show how the carbon electrodes wear away in the electrolysis of aluminium oxide
Carbon + oxygen → carbon dioxide
(C + O2 → CO2
75
What is electrode does aluminium form at during electrolysis?
Negative cathodes as aluminium is positively charged
76
What is 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 is a substance is formed at the electrode depend upon in aqueous solutions
Positive electrode: if hailide has his present, it goes to the electrodes, otherwise, oxygen always forms
Negative electrode: least reactive positive ion goes to the electrode
80
What is formed at each electrode for aqueous potassium bromide?
Hydrogen at the negative electrode : cathode as is less reactive than potassium
Bromine at the positive electrode, as is a halide
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, which then the halogen is produced
83
Why does hydrogen produced when an aqueous solution is electrolysed?
Water molecules breakdown into hydrogen ions and hydroxide ions
84
what always happens at the cathode
Gain of electrons so reduction
85
What always happens at the anode
Loss of electrons, so oxidation
86
Write a half equation for the reduction of copper ions
Cu2+ + 2e- → Cu
87
Write a half equation for the oxidation of chloride ions
2Cl- → Cl2 + 2e-
88
Write a half equation for the oxidation of oxide ions
2O2- → O2 + 4e-
89
Write a half equation for the reduction of hydrogen ions
2H+ + 2e- → H2
90
What technique can be used to measure the volumes of acids and other alkalis that reacts with each other?
Titrations
91
How do you know when the neutralisation point has been met?
Use an indicator. This will change the colour of the neutralisation point
92
What piece of equipment is used to measure the variable volume?
Burette
93
What piece of equipment is used to measure the fixed volume?
Pipette
94
How do you workout the mass in grams given the volume of a solution and concentration in mol/dm3
Workout moles, using concentration and volume (ensure volume is in dm3)
Rearrange moles, mass and Mr equation, so masses function on imput numbers
95
How to make out the concentration from a set of titration results
R ) 1. You are very likely to be given a set of results where you need to calculate the mean titre (excluding anomalies)
2. Using the concentration and mean titre volume work out the number of moles
3. Use the balance equation and ratio to work out the number of moles for the concentration you are trying to work out.
Using the moles and volume (will be a fixed volume usually around 25 cm³) in the question, workout the concentration
