Electrochemical cells and cell potentialsEdexcel International A Level Chemistry: Mind map

Exam questions on Electrochemical cells and cell potentials

1. A cell is built from a zinc half-cell and a copper half-cell under standard conditions. Standard electrode potentials: Zn²⁺(aq)|Zn(s) −0.76 V; Cu²⁺(aq)|Cu(s) +0.34 V.
   Write the overall ionic equation for the cell reaction, including state symbols, and state the direction of electron flow in the external circuit.2 marks
2. A student builds a cell from a silver half-cell and an iron(III)/iron(II) half-cell, both under standard conditions. Standard electrode potentials: Ag⁺(aq)|Ag(s) +0.80 V; Fe³⁺(aq)|Fe²⁺(aq) +0.77 V.
   The student repeats the experiment using 0.50 mol dm⁻³ silver nitrate solution in the silver half-cell. Explain why the cell emf would no longer be the standard value of E°cell.2 marks
3. A data table gives these standard electrode potentials: Mg²⁺(aq)|Mg(s) −2.37 V; Ni²⁺(aq)|Ni(s) −0.25 V; Ag⁺(aq)|Ag(s) +0.80 V; Cl₂(g)|Cl⁻(aq) +1.36 V.
   A cell is made from the Mg²⁺|Mg and Ni²⁺|Ni half-cells under standard conditions. Write the cell diagram and calculate E°cell.3 marks