1.1. An electrolysis experiment is carried out on different solutions, J, K and L.

Electricity is passed through each solution as shown in Figure 3.

Figure 3

Any products formed at the electrodes are identified.

The results are given in Figure 4.

Figure 4

i) State an improvement that can be made to the circuit to show that a current is flowing during the electrolysis.

(1)

Some of these solutions are electrolytes.

ii) State what is meant by the term electrolyte.

(2)

iii) Which of J, K and L are electrolytes?

(1)

1.2. Copper sulfate solution was electrolysed for five minutes using copper electrodes.

Figure 5 shows the mass of the anode and of the cathode before electrolysis and after electrolysis.

Figure 5

Calculate the mass of copper deposited.

mass of copper deposited = ............................................................... g

1.3. Identify the products formed at the anode and cathode when molten potassium iodide is electrolysed.

Anode ...................................

Cathode ................................

1.4. In a different electrolysis, molten sodium fluoride is decomposed.

2NaF → 2Na + F₂

(relative atomic masses: F = 19, Na = 23)

(relative formula mass NaF = 42)

Calculate the maximum mass of sodium that could be formed from 168g of sodium fluoride.