Chlorine reacts with potassium iodide. What would the color of the resulting sol
ID: 738365 • Letter: C
Question
Chlorine reacts with potassium iodide. What would the color of the resulting solution be? What is the oxidation half-reaction for this step?Explanation / Answer
Potassium is very soft and easily cut. The resulting surface is bright and shiny. However, this surface soon tarnishes because of reaction with oxygen and moisture from the air. If potassium is burned in air, the result is mainly formation of orange potassium superoxide, KO2. the equations for them can be expressed in full formula style e.g. Cl2(aq) + KI(aq) ==> 2KCl(aq) + I2(aq/s) OR more fundamentally as redox ionic equations with spectator ions (e.g. K+) excluded e.g. Cl2(aq) + 2 I-(aq) ==> 2Cl-(aq) + I2(aq/s) the chlorine (molecule) is reduced, oxidation state change from 0 to -1 the iodide (ion) is oxidised, oxidation state change from -1 to 0 note on the balancing: electrons are shown in the half-cell reactions BUT not in the ionic equation, getting the right ratio of one half-cell reaction to another should ensure their transfer is 'hidden'!