Chemical Changes: Oxidation & Reduction in Terms of Electrons + Half Equations (NOT DONE)

Question 1

What is the mnemonic for reduction and oxidation in terms of electrons?

Answer 1

The mnemonic for oxidation and reduction in terms of electrons is as follows:

O - oxidation
I - is
L - loss of electrons
R - reduction
I - is
G - gain of electrons

Question 1

Half-Equation / Is reduction or oxidation happening here to the Mg atom?

Mg ➔ Mg^2+➕ 2e^-

Here we have a magnesium atom forming a magnesium ion and 2 electrons.

Answer 1

The magnesium atom has been oxidised as it has lost 2 of its electrons.

Question 2

Half-Equation / Is reduction or oxidation happening here to the sulphur atom?

S ➕ 2e- ➔ S^2-

The sulphur atom has formed an ion.

(ion is a charged particle)

Answer 2

The sulphur atom has been reduced as its gained electrons.

Question 3

Half-Equation / Is reduction or oxidation happening here to the aluminium atoms?

Al ➔ Al3+ ➕ 3e-

Answer 3

The aluminium atom has been oxidised as it has lost 3 of its electrons. It is now an ion.

Question 4

Half-Equation / Is reduction or oxidation happening here to the oxygen atom?

O ➕ 2e- ➔ O2-

Answer 4

The oxygen atom has been reduced as its gained 2 electrons. Its now an ion.

Question 5

Identify in the reaction below which element has been oxidised and which has been reduced.

Zinc + Copper Sulphate ➔ Zinc Sulphate + Copper

Zn + CuSO4 ➔ ZnSO4 + Cu

ions present:
Cu^2+

Zn^2+