Chapter 7 - Oxidation, Reduction and Redox

Question 1

What is a redox reaction?

Answer 1

It is when a transfer of electrons has taken place from the reducing agent to the oxidising agent

Question 2

What is oxidation? What is an oxidising agent?

Answer 2

Oxidation can have three definitions:
Gain of oxygen
Loss of hydrogen
Loss of electrons
Therefore an oxidising agent is a chemical species which causes oxidation in other species, so it itself is reduced (gains electrons) - an electron recipient

Question 3

What is reduction? What is a reducing agent?

Answer 3

Reduction can have three definitions:
Loss of oxygen
Gain of hydrogen
Gain of electrons
Therefore a reducing agent is a chemical species which causes reductions in other species, so it itself is oxidised (loses electrons) - an electron donor

Question 4

What are the rules for assigning oxidation states? (order of priority)

Answer 4

Fluorine will always exist in a -1 state, no matter what
Group 1 and 2 metals will always exist as +1 and +1 ions respectively
Aluminium will always exist as a +3 ion
Hydrogen will only not form +1 ions when in metal hydrides
Oxygen will only not form -2 ions when in peroxide compounds (also in OF2 it takes +2 oxidation state)
Chlorine will only form -1 ions when all of the above conditions have first been met (usually only O and F will force it to become a +1 ions)

Question 5

What oxidation states do elements have?

Answer 5

Elements are always oxidation state 0

Question 6

What are half equations?

Answer 6

Half equations of a reaction are the equation which only shows the reaction with either the oxidised or reduced species, and the 2 half equations can be combined to form one complete equation

Question 7

What is a spectator ion?

Answer 7

It is an ion which does not change oxidation state during a reaction, these are very often group 1 and 2 metals which react in aqueous solution because they’re dissosciated anyway so not really relevant