1.7 Oxidation, Reduction and Redox Reactions Flashcards
What is oxidation?
● The loss of electrons
OR
● Gain of Oxygen (or any electronegative element)
OR
● Loss of Hydrogen (or any electropositive element)
What is reduction?
● The gain of electrons
OR
● Loss of Oxygen (or any electronegative element)
OR
● Gain of Hydrogen (or any electropositive element)
What is an oxidising agent?
Species that gains electrons
What is a reducing agent?
Species that loses electrons
Define oxidation state.
A number which represents the number of electrons lost or gained by an atom of that element in the
compound. (If electrons are lost number is positive, if electrons are gained number is negative.)
What is the oxidation state of oxygen in OF2 ?
[O] = +2
Otherwise [O] = -2 in most other compounds
What is the oxidation state of hydrogen in KH ?
([H] = -1 is for metal hydrides. Otherwise [H] = +1 in most other compounds)
What is the oxidation state of chlorine in NaClO ?
[Cl] = +1
Otherwise [Cl] = -1 in most other compounds. NaClO is formed in a disproportionation reaction.
Define the term disproportionation
Where in a redox reaction, the oxidation states of atoms of the same element, increase for some atoms, whereas decrease for some atoms.
What is the oxidation state of phosphorus in PCl5 ?
[P] = +5
What is the oxidation state of nitrogen in ammonia?
[N] = -3
As ammonia is NH3
What is the oxidation state of arsenic in AsO4-3 ?
[As] = +5
What is the oxidation state of iron in K4Fe(CN)6?
[Fe] = +2
Why is 1s22s22p5 a weaker reducing agent than 1s22s22p63s23p64s2 ?
The 2p electron is closer to the nucleus (smaller atom) than the 4s electron. Hence the nuclear attraction is stronger so the 2p electron is lost less easily than the 4s electron.
What happens in a redox reaction.
● Electrons are transferred from one species
(element) to another.
● One element is oxidised whilst another is
reduced.
