This question is about metals and the reactivity series - AQA - GCSE Chemistry - Question 2 - 2020 - Paper 1

The pale grey crystals observed in the reaction indicate that silver has been displaced from the silver nitrate solution. This suggests that copper is more reactive than silver, as it can displace silver ions from the solution. Additionally, the blue color of the solution suggests the formation of copper ions, which further confirms that copper is replacing silver.

1. Add the metals X, Y, and Z separately to a test tube containing dilute hydrochloric acid.
2. Observe and record the reaction of each metal.
   • For copper, expect no reaction; there should be no bubbles or change.
   • For magnesium, look for vigorous bubbling and a temperature increase, and note that it forms a colourless solution.
   • For iron, note bubbles, but expect a less vigorous reaction than magnesium, and observe a coloured solution.
3. Control variables to ensure accurate results:
   • Use the same concentration and volume of hydrochloric acid for each test.
   • Ensure each metal sample has the same mass.
   • Maintain the same temperature during the experiments.

To calculate the relative atomic mass (A_r) of metal M, use the formula:

$A_r = \frac{(203 \times 30) + (205 \times 70)}{100}$

Calculating:

• Numerator: (203 × 30) + (205 × 70) = 6090 + 14350 = 20440
• Denominator: 100

Thus, the relative atomic mass A_r = \frac{20440}{100} = 204.4.

Therefore, the answer to 1 decimal place is 204.4.