[CKabes]

What's really going on in this reaction? I'm sure it's not happening how the description says it is.

http://www.youtube.com/watch?v=QZLxtbz__XQ&feature=plcp&context=C4ac5933VDvjVQa1PpcFO4LWMx4Vs7twUB7bYBWyj5kGQdLCdOlvE%3D

NaHSO₄ is added to a solution of KI
I assume this is to simply make the solution acidic

Next, H₂O₂ is added and an obvious oxidation takes place, because the Iodine turns brown

Finally, the solution is filtered and solid iodine is present?

What's happening here?

[Olympiad_Tutor]

Iodine is a solid at room temperature.
What is its solubility in water?

[manofohm]

Your sodium bisulfate is displacing the potassium leaving you with a hydrogen iodide solution then when you add the H2O2 the hydrogen iodide is oxidized leaving you with elemental iodine. There is actually a series of reaction intermediates between the hydrogen iodide and the final Iodine formation involving the formation of hydrogen triiodide

NaHSO4 + KI------> NaKSO4 + HI
2HI + H2O2 --------> I2 + 2H2O
I2+ HI-------> HI-I-I
2HI3 + H2O2 --------->3H2O + 2I2

I believe thats all the reactions taking place in an ideal system.

[Borek]

Your sodium bisulfate is displacing the potassium leaving you with a hydrogen iodide solution

No way. You have just a mixture containing all ions, there is no reaction taking place.

[vmelkon]

I agree with Borek.
You just have ions floating around in the water.
The hydrogen iodide is ionized. The H+ probably plays some kind of role in a multistep process along with the H2O2 and I- and so you have the simplified equation of
2HI + H2O2 --> I2 + 2H2O