Question 1

A student investigated the voltage produced by different pairs of metal electrodes in a chemical cell. Figure 6 shows the apparatus and Table 3 shows the results.

Table 3
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

This is the method used.

1. Place a nickel electrode and an electrode made from a different metal (electrode A) in 1.0 mol/dm3 sodium chloride solution.

2. Measure the voltage produced.

3. Repeat using different metals for electrode A.

Write the symbols of the five metals in Table 3 in order of reactivity.

Justify your answer.

Most reactive __ __ __ __ __

Least reactive __ __ __ __ __

Justification: __ __ __ __ __

Accepted Answer

1.  **Understand the setup:** A chemical cell is made with Nickel and another metal (Electrode A). The voltage is measured.
2.  **Relate voltage to reactivity:** In a chemical cell, the voltage produced depends on the difference in reactivity between the two metals. The more reactive metal will be the negative electrode and will have a more positive potential relative to the less reactive metal.
3.  **Order the metals:** The table shows the voltage of each metal relative to Nickel (which has a voltage of 0.00). A more positive voltage means the metal is more reactive than Nickel. A more negative voltage means it is less reactive than Nickel.
4.  **List the metals:** Arrange the metals in order from the most positive voltage to the most negative voltage. This will be the order of reactivity from most to least reactive.
5.  **Justify:** Explain the link between the size/sign of the voltage and the reactivity difference compared to the reference electrode (Nickel).

Question 2

What mistakes do candidates make on this AQA GCSE question?

Accepted Answer

✗ Reversing the order of reactivity.
✗ Justification is simply restating the order without explaining the principle (link between voltage and reactivity difference).
✗ Ignoring the signs of the voltages.

How to approach this question

Full Answer

Common mistakes

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