Redox reactions
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In terms of electron transfer what does reduction mean?
The gaining of electrons
In terms of electron transfer what does oxidation mean?
The loss of electrons
Define oxidising agent
A reagent that removes electrons from another species
Define reducing agent
A reagent that adds electrons to another species
Define oxidation number
A measure of the number of electrons that an atom uses to bond with atoms of another element
What is the oxidation number of uncombined atoms?
0
What is the oxidation number of: i) Group 1 elements ii) Group 2 elements
i) +1 ii) +2
What is the oxidation number of fluorine atoms?
-1
Oxygen has an oxidation number of -2, apart from when it is in what? What does the oxidation number change to in that situation?
Except when oxygen is in a peroxide when the oxidation number is -1
i) What is the oxidation number of hydrogen usually? ii) In what situation is it -1?
i) +1 ii) When it is a hydride (E.g. LiH)
How are oxidation numbers represented when naming a compound?
Roman numerals in brackets E.g. copper (II) nitrate (V)
Define oxidation in terms of oxidation number
The oxidation number becomes more positive
Define reduction in terms of oxidation number
The oxidation becomes more negative
What is oxidised and reduced in each of the following reactions? i) Mg + H2SO4 —>MgSO4 + H2 ii) CaCO3 + 2HCl —> CaCl2 + H2O + CO2 iii) Fe2O3 + 3CO —> Fe + 3CO2
i) Mg is oxidised as ON increases from 0 to +2, H2 is reduced as ON decreases from +1 to 0 ii) Trick question- all ON are the same so not a redox reaction iii) Fe is reduced as the ON decreases from +3 to 0, C is oxidised as the ON increases from +2 to +4