need chemical equations for two processes for a qualitative analysis lab involvi

Question

need chemical equations for two processes for a qualitative analysis lab involving a test sample of anions.

1) testing for iodide ion
test solution containing potassium iodide (KI) + Iron 3 chloride (FeCl3). this oxidized the I- to I2 then add Hexane (C6H14) and agitate to result in a purple colored layer that signifies iodide (I-) was in the test solution.

so far I have 2I- + 2Fe3+ = 2Fe2+ + I2 but I do not know how to add in the hexane.

2) test solution with potassium bromide (KBr) + chlorine water. the hexane is added and a brown layer indicated Br- was in the test mix.

it seems like hexane is only being used to identify color so I am not sure if it needs to be included as these test were to id the anions present in a test sample.

thank you in advance

Explanation / Answer

1) FeCl3 reacts with iodide (I-) to form ferric triiodide (FeI3). The triiodide (I3-) ion dissociates into iodine (I2) and I-. I2 is responsible for lending the hexane layer purple.

FeCl3 (aq) + 3 I- (aq) ------> FeI3 (aq) + 3 Cl-

This is a displacement reaction and not a redox reaction.

FeI3 (aq) ------> Fe3+ (aq) + I3- (aq)

I3- (aq) -----> I2 (aq) + I- (aq)

I2 (aq) + hexane ------> purple color

2) Chlorine water (an aqueous solution of chlorine, Cl2) displaces bromide (Br-) to form bromine (Br2). Br2 is responsible for making the hexane layer reddish-brown.

2 KBr (aq) + Cl2 (aq) -------> 2 KCl (aq) + Br2 (aq)

Br2 (aq) + hexane ------> brown color

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