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Help with chemical reaction

Posted: Thu Jul 25, 2024 12:19 am
by Mawkish
I had a lab and now im bit confused about the reaction
What I did is I added 4 drops of 0,1 m FeCl3 to 4 drops of 0,1 m KI. Then i added C6H6 and shaked the test tube a bit. Result was Oily yellow colored benzene like liquid and above it dark blood red liquid.

1st reaction is simple which has 2 options i came up FeCl3 + KI --- FeCl3 + 3 KI = FeI3 + 3 KCl

and the 2nd one would be

2 FeCl3 + 2 KI = 2 FeCl2 + I2 + 2 KCl

2nd reaction seemed to fit better in this situation due the free I2, because FeCl2 or KI salts dont react with benzene.

So my problem is what happened with the benzene and free iodide. Does it form a C6H5I or something else?

Re: Help with chemical reaction

Posted: Thu Jul 25, 2024 1:02 am
by ChenBeier
It's only iodine dissolved in benzene and also in water.
A reaction of iodine with benzene need other stronger reactants
.

Re: Help with chemical reaction

Posted: Mon Jul 29, 2024 7:13 pm
by levelexpect
Mawkish wrote: Thu Jul 25, 2024 12:19 am I had a lab and now im bit confused about the reaction
What I did is I added 4 drops of 0,1 m FeCl3 to 4 drops of 0,1 m KI. Then i added C6H6 and shaked the test tube a bit. Result was Oily yellow colored benzene like liquid and above it dark blood red liquid.

1st reaction is simple which has 2 options i came up FeCl3 + KI --- FeCl3 + 3 KI = FeI3 + 3 KCl

and the 2nd one would be

2 FeCl3 + 2 KI = 2 FeCl2 + I2 + 2 KCl

2nd reaction seemed to fit better in this situation due the free I2, because FeCl2 or KI salts dont react with benzene.

So my problem is what happened with the benzene and free iodide. Does it form a C6H5I or something else?
The oily yellow liquid is likely iodobenzene (C₆H₅I), which forms due to the reaction of iodine (I2) with benzene (C6H6) in the presence of the iron(III) chloride catalyst. The dark blood-red liquid is iodine dissolved in benzene.

Re: Help with chemical reaction

Posted: Mon Jul 29, 2024 9:53 pm
by ChenBeier
This works only in absence of water.