KI solution color change in tap water.

In summary, the conversation discusses a reaction involving KI and tap water. The speaker had a beaker with 10ml of KI and when they added tap water, the solution turned clear yellow. They are curious about what caused this reaction and what substance was produced to create the yellow color. They mention previous experiments showing that increasing I3- concentration in a solution can turn it yellow. The speaker also suggests that the KI may have been old and contained elemental iodine.
  • #1
amorale
5
0
Hello,

My question is regarding a reaction with KI with some chemical in tap water.
Today I was working on a lab at school and had a beaker with about 10ml of 100mM KI in it, when I went to clean it and put tap water in the solution it automatically turned clear yellow.

So I was wondering what may have been in the tap water that made it react that way and also what exactly was being produce in the reaction that made the color yellow.

I know from previews experiments that if you increase I3- concentration in a solution it will turn yellow after a couple of minutes, so was I3- being form in this reaction or was it another Iodine ion?

Thank You, if you need me to clarify something please just ask.
 
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  • #2
There seems to be a lot of things that will turn yellow when KI is added to it.
It could be just that the KI was old and it had some elemental iodine in it.
 

1. Why does KI solution change color in tap water?

KI solution contains potassium iodide, which reacts with the chlorine in tap water to form iodine. The iodine then reacts with the starch in the solution, causing it to change color.

2. What causes the color change in KI solution and tap water?

The color change is caused by a chemical reaction between the potassium iodide and chlorine in tap water, which produces iodine. The iodine then reacts with the starch in the solution, resulting in a color change.

3. How can the color change in KI solution be used in scientific experiments?

The color change in KI solution can be used as an indicator of the presence of starch or chlorine in a solution. It is often used in titration experiments to determine the concentration of certain chemicals in a solution.

4. Does the color change in KI solution depend on the quality of tap water?

No, the color change in KI solution is not affected by the quality of tap water. As long as there is chlorine present in the water, the color change will occur.

5. How can the color change in KI solution be reversed?

The color change in KI solution can be reversed by adding a reducing agent, such as sodium thiosulfate, which will convert the iodine back to iodide ions. This will restore the original color of the solution.

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