Edexcel International A Level Chemistry
Topic 8
Redox &
Groups 1, 2 and 7
Topic 8 brings together redox chemistry and the inorganic chemistry of the s-block and Group 7. Part 8A builds oxidation numbers, half-equations and disproportionation; 8B covers the trends and reactions of Groups 1 and 2, their compounds, tests for ions and titrations; 8C covers the halogens as oxidising agents, the disproportionation reactions of chlorine and the halide ions. All of it is examined in Unit 2 and assessed practically through Core Practicals 3 and 4.
Exam Unit
Unit 2
WCH12/01 – IAS
Specification Points
8.1 – 8.28
28 points covered
Topic Parts
3 parts
15 revision pages
Exam Board
Edexcel IAL
Pearson International
Revision Notes
8.1 – 8.10
Redox
Chemistry
Chemistry
oxidation numbers, half-equations, disproportionation
1
Available
Topic 8A Redox Chemistry
Oxidation numbers and their rules, electron transfer and half-equations, disproportionation, and classifying unfamiliar reactions as redox.
Start revising8.11 – 8.23
Groups
1 and 2
1 and 2
trends, reactions, tests, titrations
2
Available
Topic 8B Groups 1 and 2
Trends down the s-block, reactions of the elements and their compounds, solubility and thermal stability, flame colours, tests for ions, titrations and uncertainty.
Start revising8.24 – 8.28
Group 7
halogens and halide ions
3
Available
Topic 8C Group 7
Trends in the halogens, displacement and oxidising power, the disproportionation reactions of chlorine, and the halide ions as reducing agents with their tests.
Start revisingSpecification Coverage
Topic 8 Redox Chemistry and Groups 1, 2 and 7 – Edexcel International A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 8.
8A: Redox Chemistry
8.1
know what is meant by the term ‘oxidation number’ and understand the rules for assigning oxidation numbers
8.2
be able to calculate oxidation numbers of elements in:
i
compounds
ii
ions
iii
peroxides
iv
metal hydrides
8.3
be able to indicate the oxidation number of an element in a compound or an ion, using a Roman numeral
8.4
be able to write formulae given oxidation numbers
8.5
understand oxidation and reduction in terms of:
i
electron transfer
ii
changes in oxidation number
iii
application to reactions of s-block and p-block elements
8.6
know that oxidising agents gain electrons and reducing agents lose electrons
8.7
understand that a disproportionation reaction involves an element in a single species being simultaneously oxidised and reduced
8.8
know that oxidation number is useful for classifying reactions as redox or disproportionation
8.9
understand that metals generally form positive ions by loss of electrons with an increase in oxidation number, and that non-metals generally form negative ions by gain of electrons with a decrease in oxidation number
8.10
be able to write ionic half-equations and use them to construct full ionic equations
8B: The Chemistry of Groups 1 and 2
8.11
understand reasons for the trend in ionisation energy down Groups 1 and 2
8.12
understand reasons for the trend in reactivity down Group 1 (Li to K) and Group 2 (Mg to Ba)
8.13
know the reactions of the Group 1 elements Li to K and the Group 2 elements Mg to Ba with:
i
oxygen
ii
chlorine
iii
water
8.14
know the reactions of:
i
oxides of Group 1 and 2 elements with water and dilute acid
ii
hydroxides of Group 1 and 2 elements with dilute acid
8.15
know the trends in solubility of Group 2 hydroxides and sulfates
8.16
understand reasons for the trends in thermal stability of Group 1 and 2 nitrates and carbonates in terms of cation size and charge
8.17
understand the formation of characteristic flame colours by Group 1 and 2 compounds in terms of electron transitions, and know the flame colours
8.18
know experimental procedures to show:
i
patterns in the thermal decomposition of Group 1 and 2 nitrates and carbonates (including the tests for carbon dioxide and oxygen)
ii
flame colours in compounds of Group 1 and 2 elements
8.19
know reactions, including ionic equations where appropriate, for identifying:
i
carbonate ions, CO₃²⁻, and hydrogencarbonate ions, HCO₃⁻, using an aqueous acid to form carbon dioxide
ii
sulfate ions, SO₄²⁻, using acidified barium chloride solution
iii
ammonium ions, NH₄⁺, using sodium hydroxide solution and warming to form ammonia
8.20
be able to calculate solution concentrations, in mol dm⁻³ and g dm⁻³, including simple acid-base titrations using the indicators methyl orange and phenolphthalein
8.21
CORE PRACTICAL 3: Finding the concentration of a solution of hydrochloric acid
8.22
understand how to minimise the sources of measurement uncertainty in volumetric analysis and estimate the overall uncertainty in the calculated result
8.23
CORE PRACTICAL 4: Preparation of a standard solution from a solid acid and use it to find the concentration of a solution of sodium hydroxide
8C: Inorganic Chemistry of Group 7
8.24
understand reasons for the trends for Group 7 elements in:
i
melting and boiling temperatures and physical state at room temperature
ii
electronegativity
iii
reactivity down the group
8.25
understand the trend in reactivity of Group 7 elements in terms of redox reactions of Cl₂, Br₂ and I₂ with halide ions in aqueous solution, and know the colours of the elements in standard conditions, in aqueous solution and in a non-polar organic solvent
8.26
understand, in terms of changes in oxidation number, the following reactions of the halogens:
i
oxidation reactions with Group 1 and 2 metals
ii
the disproportionation reaction of chlorine with water and the use of chlorine in water treatment
iii
the disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide to form bleach
iv
the disproportionation reaction of chlorine with hot alkali
v
reactions analogous to those specified above
8.27
understand the following reactions:
i
solid Group 1 halides with concentrated sulfuric acid, to illustrate the trend in reducing ability of the hydrogen halides
ii
precipitation reactions of the aqueous anions Cl⁻, Br⁻ and I⁻ with aqueous silver nitrate solution and nitric acid, and the solubility of the precipitates in aqueous ammonia
iii
hydrogen halides with ammonia gas (to produce ammonium halides) and with water (to produce acids)
8.28
be able to make predictions about fluorine and astatine and their compounds using knowledge of trends in halogen chemistry
Specification Coverage
Topic 8 Redox Chemistry and Groups 1, 2 and 7 – Edexcel International A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 8.
8A: Redox Chemistry
8.1
know what is meant by the term ‘oxidation number’ and understand the rules for assigning oxidation numbers
8.2
be able to calculate oxidation numbers of elements in:
i
compounds
ii
ions
iii
peroxides
iv
metal hydrides
8.3
be able to indicate the oxidation number of an element in a compound or an ion, using a Roman numeral
8.4
be able to write formulae given oxidation numbers
8.5
understand oxidation and reduction in terms of:
i
electron transfer
ii
changes in oxidation number
iii
application to reactions of s-block and p-block elements
8.6
know that oxidising agents gain electrons and reducing agents lose electrons
8.7
understand that a disproportionation reaction involves an element in a single species being simultaneously oxidised and reduced
8.8
know that oxidation number is useful for classifying reactions as redox or disproportionation
8.9
understand that metals generally form positive ions by loss of electrons with an increase in oxidation number, and that non-metals generally form negative ions by gain of electrons with a decrease in oxidation number
8.10
be able to write ionic half-equations and use them to construct full ionic equations
8B: The Chemistry of Groups 1 and 2
8.11
understand reasons for the trend in ionisation energy down Groups 1 and 2
8.12
understand reasons for the trend in reactivity down Group 1 (Li to K) and Group 2 (Mg to Ba)
8.13
know the reactions of the Group 1 elements Li to K and the Group 2 elements Mg to Ba with:
i
oxygen
ii
chlorine
iii
water
8.14
know the reactions of:
i
oxides of Group 1 and 2 elements with water and dilute acid
ii
hydroxides of Group 1 and 2 elements with dilute acid
8.15
know the trends in solubility of Group 2 hydroxides and sulfates
8.16
understand reasons for the trends in thermal stability of Group 1 and 2 nitrates and carbonates in terms of cation size and charge
8.17
understand the formation of characteristic flame colours by Group 1 and 2 compounds in terms of electron transitions, and know the flame colours
8.18
know experimental procedures to show:
i
patterns in the thermal decomposition of Group 1 and 2 nitrates and carbonates (including the tests for carbon dioxide and oxygen)
ii
flame colours in compounds of Group 1 and 2 elements
8.19
know reactions, including ionic equations where appropriate, for identifying:
i
carbonate ions, CO₃²⁻, and hydrogencarbonate ions, HCO₃⁻, using an aqueous acid to form carbon dioxide
ii
sulfate ions, SO₄²⁻, using acidified barium chloride solution
iii
ammonium ions, NH₄⁺, using sodium hydroxide solution and warming to form ammonia
8.20
be able to calculate solution concentrations, in mol dm⁻³ and g dm⁻³, including simple acid-base titrations using the indicators methyl orange and phenolphthalein
8.21
CORE PRACTICAL 3: Finding the concentration of a solution of hydrochloric acid
8.22
understand how to minimise the sources of measurement uncertainty in volumetric analysis and estimate the overall uncertainty in the calculated result
8.23
CORE PRACTICAL 4: Preparation of a standard solution from a solid acid and use it to find the concentration of a solution of sodium hydroxide
8C: Inorganic Chemistry of Group 7
8.24
understand reasons for the trends for Group 7 elements in:
i
melting and boiling temperatures and physical state at room temperature
ii
electronegativity
iii
reactivity down the group
8.25
understand the trend in reactivity of Group 7 elements in terms of redox reactions of Cl₂, Br₂ and I₂ with halide ions in aqueous solution, and know the colours of the elements in standard conditions, in aqueous solution and in a non-polar organic solvent
8.26
understand, in terms of changes in oxidation number, the following reactions of the halogens:
i
oxidation reactions with Group 1 and 2 metals
ii
the disproportionation reaction of chlorine with water and the use of chlorine in water treatment
iii
the disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide to form bleach
iv
the disproportionation reaction of chlorine with hot alkali
v
reactions analogous to those specified above
8.27
understand the following reactions:
i
solid Group 1 halides with concentrated sulfuric acid, to illustrate the trend in reducing ability of the hydrogen halides
ii
precipitation reactions of the aqueous anions Cl⁻, Br⁻ and I⁻ with aqueous silver nitrate solution and nitric acid, and the solubility of the precipitates in aqueous ammonia
iii
hydrogen halides with ammonia gas (to produce ammonium halides) and with water (to produce acids)
8.28
be able to make predictions about fluorine and astatine and their compounds using knowledge of trends in halogen chemistry
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