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Ordering metals using cell voltages
A student investigated the voltage produced by different pairs of metal electrodes in a chemical cell.
- Place a nickel electrode and an electrode made from a different metal (electrode A) in 1.0 mol/dm³ sodium chloride solution.
- Measure the voltage produced.
- Repeat using different metals for electrode A.
| Electrode A | Symbol of metal | Voltage in volts |
|---|---|---|
| Copper | Cu | −0.59 |
| Magnesium | Mg | 2.12 |
| Nickel | Ni | 0.00 |
| Silver | Ag | −1.05 |
| Zinc | Zn | 0.51 |
Write the symbols of the five metals in Table 3 in order of reactivity. Justify your answer.
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Marking points
- 1 Order begins Mg, Zn, Ni.
- 2 Order continues Ni, Cu, Ag, producing Mg → Zn → Ni → Cu → Ag overall.
- 3 Justification correctly links voltage sign/value or voltage magnitude to reactivity.
Full-mark answer
Most reactive → least reactive: Mg, Zn, Ni, Cu, Ag. The more positive the voltage relative to nickel, the more reactive the metal; the most negative voltage identifies the least reactive metal.
Why this answer loses marks
I ordered the metals by voltage magnitude only.
The sign relative to the reference metal sets the reactivity direction before magnitude refines the order.