Sulfur dioxide gas, is bubbled through iodine solution, until no further change occurs. During the reaction the sulfur dioxide is oxidised to form sulfate ions.
1. Describe the colour change that occurs.
2. Link this colour change to species involved in this reaction.
3. Write the half-equation for the reduction of iodine that occurs during this reaction.
Colour change is brown to colourless.
The colour of the `I_2` solution is brown. So initially the colour of the solution is brown.
When SO_2 is bubbled in to the `I_2` solution, `SO_2` reacts with `I_2` an form `SO^(2-)_4` and `I^-` .
`SO^(2-)_4 ` and `I^-` are colourless. So the brownish colour of the solution will gradually decrease. When sufficient `I_2` was introduced to react all the `I_2` in the solution the colour of the solution will become colourless.
`I_2+2e rarr 2I^-`