A-Level Chemistry Specification

OCR A H432

Section 2.1.5: Redox

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#2.1.5a

rules for assigning and calculating oxidation number for atoms in elements, compounds and ions

Learners will be expected to know oxidation numbers of O in peroxides and H in metal hydrides.

#2.1.5b

writing formulae using oxidation numbers

#2.1.5c

use of a Roman numeral to indicate the magnitude of the oxidation number when an element may have compounds/ions with different oxidation numbers

Examples should include, but not be limited to, iron(II) and iron(III).
Learners will be expected to write formulae from names such as chlorate(I) and chlorate(III) and vice versa.
Note that 'nitrate’ and ‘sulfate’, with no shown oxidation number, are assumed to be NO3 and SO42–.

#2.1.5d

oxidation and reduction in terms of:

(i) electron transfer
(ii) changes in oxidation number

Should include examples of s-, p- and d-block elements.

#2.1.5e

redox reactions of metals with acids to form salts, including full equations (see also 2.1.4c)

Metals should be from s-, p- and d-blocks e.g. Mg, Al, Fe, Zn.
Ionic equations not required.
In (e), reactions with acids will be limited to those producing a salt and hydrogen. Reactions involving nitric acid or concentrated sulfuric acid could be assessed in the context of (f).

#2.1.5f

interpretation of redox equations in (e), and unfamiliar redox reactions, to make predictions in terms of oxidation numbers and electron loss/gain.