Question

In the balanced half-reaction MNO₄⁻ + e⁻ + H → Mn²⁺ + H₂O, what is the coefficient for H when all coefficients are reduced to the lowest whole number?

a) 1
b) 2
c) 3
d) 4

Answer 1

The coefficient for hydrogen (H) in the given balanced half-reaction is 8. This is determined by balancing the oxygen and hydrogen atoms in the reaction and reducing the coefficients to the lowest whole numbers.

Step-by-step explanation:

The student's question asks for the coefficient of hydrogen (H) in the balanced half-reaction MnO₄⁻ + e⁻ + H → Mn²⁺ + H₂O when the coefficients are reduced to the lowest whole number. To balance the half-reaction in an acidic solution, we need to ensure mass and charge balance. Balancing the oxygen first, we see that we need 4 water molecules (H₂O) to balance the 4 oxygen atoms in MnO₄⁻. This introduces 8 hydrogen atoms on the product side. To balance the hydrogen atoms, we would need 8 H⁺ on the reactant side. Therefore, the full balanced equation is MnO₄⁻ + 8 H⁺ + 5 e⁻ → Mn²⁺ + 4 H₂O. When reduced to the lowest whole numbers, coefficients remain the same because they are already at their lowest integer values. The coefficient for H (hydrogen) is 8, which is not stated in the options provided by the question.