C7 - Redox Reactions Flashcards
What is a redox reaction?
A reaction in which reduction and oxidation occurs simultaneously
What is oxidation?
Addition of oxygen
Loss of hydrogen
Loss of electrons
What is reduction?
Loss of oxygen
Gain of hydrogen
Gain of electrons
What are oxidising agents?
Oxidise other species
Accept electrons
Are themselves reduced
What are reducing agents?
Reduce other species
Donate electrons
Are themselves oxidised
What is oxidation state?
A numerical value of the degree of oxidation or reduction
of an atom/element
How do you determine the maximum oxidation state?
The group number
How do you determine the minimum oxidation state?
Group number - 8
During oxidation what happens to the oxidation state?
It increases
H2 → 2H+ + 2e-
Oxidation number goes from 0 to 1
During reduction what happens to the oxidation state?
It decreases
Fe3+ + e- → Fe2+
Oxidation number goes from 3+ to 2+
What is a half equation?
An equation that includes electrons and helps to show the oxidation and reduction processes in a chemical reaction
How can half equations be balanced?
Using electrons
Water molecules
H+ ions in acidic conditions
OH- ions in alkali conditions
What is a displacement reaction?
When a more reactive element displaces a less reactive element
Equations can be split into 2 half equations, one for oxidation, one for reduction
What is a spectator ion?
Ions that are not directly involved in the reaction
What is a disproportionation reaction?
A disproportionation reaction is one in which the same species is both oxidized and reduced
E.g. 2NaOH + Cl2 → NaCl + NaOCl + H2O
(Reduced in NaCl and oxidised in NaOCl)
