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For an electrochemical cell based on the reaction Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g), what happens if H2SO4 is added to the cathode compartment?

1. The cell emf rises and the equilibrium moves toward products
2. The cell emf falls and the equilibrium moves toward products
3. The cell emf falls and the equilibrium moves toward reactants
4. The cell emf rises and the equilibrium moves toward reactants

Correct answer: The cell emf rises and the equilibrium moves toward products

Solution

Adding H2SO4 increases the concentration of H+ ions in the cathode compartment, which drives the reduction of H+ to H2, thus increasing the cell's emf and shifting the equilibrium toward the products.

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