5. (a) 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

Chlorine is reduced in this reaction because it gains electrons. The balanced equation shows that chlorine ($Cl_2$) reacts with potassium bromide ($2KBr$) to produce potassium chloride ($2KCl$) and bromine ($Br_2$). This indicates that chlorine ions ($Cl^-$) are formed from the chlorine molecule, demonstrating a gain of electrons in the process, which confirms that chlorine has been reduced.

The half equation for the formation of bromine from bromide ions can be written as:

The balanced equation for the reaction between aluminium and chlorine to form aluminium chloride is:

To demonstrate that charged particles are present in the solution, an experiment can be conducted using a simple circuit. A light bulb and a power supply can be set up with electrodes immersed in the ionic solution. When the solution conducts electricity, the light bulb will illuminate, indicating the presence of charged ions. Additionally, observing electrolysis effects, such as gas bubbles forming at the electrodes, further confirms the presence of charged particles in the solution.