Australia's Science Forum

Hi all,

I have a question about the colour of Potassium Iodide.
I have a small amount in a bottle, made up some time ago, that is a strong yellow colour.
I needed to make some up today, it is clear.
The older solution says saturated, the one I made today is 2M.
What colour should it be ???

TIA
Helen.

Hi Helen. I've got saturated KI in the chem store, which is quite yellow, and some 1M, which is clear. So your 2M stuff should probably be clear.

Thanks Marama T

Potassium iodide is usually reacted with lead nitrate to give a bright yellow precipitate.
Could it be that your potassium iodide is contaminated?

Potassium iodide of any strength 1M or 2M, will eventually turn yellow in its container, usually pale yellow. That colour change happens after a long period of time. Even my 0.1M solution has a faint hint of colour but it has been sitting on the shelf for a long time. So I may have to make up a fresh batch when it is next required. The saturated solution is a dark yellow right now. Another fresh batch coming up when someone needs it.

Thanks for the replies, everyone!

maybe it is Iodine (Potassium Iodide)