This is about electrolysis - AQA - GCSE Chemistry Combined Science - Question 1 - 2018 - Paper 1

Copper is less reactive than hydrogen. This indicates that copper can be reduced at the cathode, while hydrogen is produced at a lower reactivity.

To find the mean mass of copper produced after 3 minutes, we can use the values from Table 1:

Experiment 1: 2.40 mg Experiment 2: 2.41 mg Experiment 3: 2.39 mg

Mean mass = ( \frac{2.40 + 2.41 + 2.39}{3} = 2.40 , \text{mg} )

From Table 1, to find the mass X after 5 minutes, we have: Mass after 5 minutes for Experiment 1: 3.02 mg Mass after 5 minutes for Experiment 3: 3.01 mg

Mean mass for 5 minutes = ( \frac{3.02 + 3.01 + X}{3} ) Setting equal to the mean (as we see that Experiment 2 is in the range of the others), we can approximate: Mean = 3.06 mg thus, X is calculated to yield approximately 3.06 mg.

We know that the copper chloride solution contained 300 grams per dm³. The student used 50 cm³ of this solution in each experiment. Therefore:

Mass of CuCl₂ in 50 cm³ = ( 300 , \text{g/dm}^3 \times \frac{50}{1000} , \text{dm}^3 = 15 , \text{g} )

Thus, the mass of solid copper chloride used in each experiment is 15 g.