5.4.1.4 Oxidation and Reduction in Terms of Electrons

Question 1

What is oxidation?

Answer 1

• loss of electrons

Question 2

What is reduction?

Answer 2

• gain of electrons

Question 3

How do you write an ionic equation (example is sodium being oxidised)?

Answer 3

• lost an electron so it is a +1 charge
• Na → Na+ + e- (products are reactants when sodium is reduced)
• charges on each side of equation should add up to same number

Question 4

How can you tell which element has been oxidised and reduced in an equation (e.g. 2Na + 2HCl → 2NaCl +H2)?

Answer 4

• HCl is made up of H+ ions and Cl- ions
• NaCl is made up of Na+ ions and Cl- ions
• sodium has been oxidised as it lost electrons
• chlorine has not been oxidised or reduced
• hydrogen has been reduced as it gained electrons