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, chlorine is reduced because it gains electrons. The equation for the reaction is:

$Cl_2 + 2Br^- \rightarrow 2Cl^- + Br_2$

In this reaction, chlorine goes from a zero oxidation state in Cl2 to a negative oxidation state in Cl- as it gains electrons, indicating a reduction process.

The half equation for the formation of bromine from bromide ions is:

$2Br^- \rightarrow Br_2 + 2e^-$

The balanced equation for the reaction between aluminium and 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 involves using electrodes connected to a power supply. When solid ionic compound is dissolved in water, inserting the electrodes into the solution and observing whether a current flows can indicate the presence of charged particles. If a current is observed, it confirms the presence of ions in the solution.