Describe what is seen when chlorine water is added to potassium bromide solution and the mixture shaken - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2018 - Paper 1

In the reaction ( Cl_2 + 2KBr \rightarrow 2KCl + Br_2 ), chlorine is reduced as it gains electrons to form chloride ions. The reduction process is demonstrated by the half-reaction: ( Cl_2 + 2e^- \rightarrow 2Cl^- ). Here, the chlorine molecule ( Cl_2 ) gains two electrons to become two chloride ions, indicating a reduction in oxidation state from 0 to -1.

The half equation for the formation of bromine from bromide ions is given by: ( 2Br^- \rightarrow Br_2 + 2e^- ). This equation shows that two bromide ions lose two electrons to form one molecule of bromine.

The balanced equation for the reaction of aluminium with chlorine to form aluminium chloride is: ( 2Al + 3Cl_2 \rightarrow 2AlCl_3 ).

A simple experiment to demonstrate the presence of charged particles in a solution is to set up a circuit with a battery, wires, and two electrodes immersed in the solution. When a solid ionic compound, like sodium chloride, is dissolved in water, and the circuit is completed, a current will flow due to the movement of ions. Observing the circuit shows that the light bulb lights up or the ammeter registers a current, confirming the presence of charged particles in the solution.