The half-reaction method
Answers are for parents and teachers.
1
Find the sum of all coefficients in 2KMnO₄ + 5Na₂SO₃ + 3H₂SO₄ = 2MnSO₄ + 5Na₂SO₄ + K₂SO₄ + 3H₂O.
21
2
What is the sum of the coefficients in Cr(OH)₃ + 5OH⁻ − 3e⁻ → CrO₄²⁻ + 4H₂O (alkaline medium)?
14
3
What is the sum of the coefficients in the ionic equation 2MnO₄⁻ + 5H₂O₂ + 6H⁺ → 2Mn²⁺ + 5O₂ + 8H₂O?
28
4
Find the sum of the coefficients in Cl₂ + 2OH⁻ → Cl⁻ + ClO⁻ + H₂O.
6
5
Why must the numbers of electrons be equalised before the half-reactions are added?
The electrons accepted by the oxidising agent must equal those given by the reducing agent.