What is the order of decreasing reactivity of these four metals? Tick (✓) one box - AQA - GCSE Chemistry Combined Science - Question 1 - 2019 - Paper 1

1. Mass of metal used: Ensuring the same amount of metal is tested helps in measuring reactivity accurately.

2. Concentration of hydrochloric acid: Having a consistent concentration will provide fair comparison of the metal reactions.

The independent variable in this reaction is the type of metal/element being tested against hydrochloric acid.

Beryllium is predicted to be less reactive than magnesium.

Reason: Beryllium is higher in the group compared to magnesium, and reactivity decreases as you move up the group in the periodic table due to stronger nuclear attraction making it harder to lose electrons.

To calculate the concentration, use the formula:

$ext{Concentration} = \frac{\text{mass of solute}}{\text{volume of solution}}$

1. Convert volume from cm³ to dm³: $50 \text{ cm}^3 = 0.05 \text{ dm}^3$
2. Use the mass of hydrogen chloride which is 3.2 g: $\text{Concentration} = \frac{3.2 g}{0.05 dm^3} = 64 g/dm^3$

Thus, the concentration of hydrogen chloride is 64 g per dm³.