[CopperSmurf]

My lab instructor asked me a simple question about what temperature I'd expect during the steam distillation I was doing. I was finishing up my Sandmeyer reaction of CuCl with my o-toluidine and the NO₂ and basically doing steam distillation on that before doing the separation process work-up (by adding acid then base, removing the color, etc).
Anyways, I told my instructor that it would be around 100 degrees since it had mostly water in it and that the water will boil before the product does because it has a higher boiling point than water.
Then, the instructor got really shocked/mad (funny and scary ) and demanded a proper answer the next time I see her. She said there's something special about steam distillation compared to the regular simple distillation but she didn't tell me.
(sorry for edit, accidently pressed enter and it saved)

So I'm obviously not getting it about steam distillation  If it's boiling at 100 degrees due to water, and the product has a higher boiling point than that, then the water will just simply boil with my product into my collection flask. So, I don't see how this is special since it looks like a purification process to me. Any ideas what she might've meant?

[Mitch]

This seems to have a good description as is: http://en.wikipedia.org/wiki/Steam_distillation

[CopperSmurf]

thanks. I guess wikipedia has good explanations for just about everything. haha.   

[Two00proof]

First and formost, Do Not tell your TA that you got your answer from Wikipedia.  They hate that.
What she was looking for was an explanation of boiling point depression.  With steam distillation, the desired product is carried over with the water molecules at a lower temperature than either of the two components.  This is similar to an azeotrope. 

She probably thought you were describing a simple distillation.  Which only brings over a single component at any given time.  So what I recommend is that you hammer home the idea that the two components are coming over at the same time.

[CopperSmurf]

thanks for the warning Two00proof, but I've already told TA about wikipedia before (last year) and let's just say it didn't turn out very well.  I'll never mention wikipedia to them ever again. So boiling point goes down, so water and product gets carried over together, so product doesn't decompose, I think I hammered it in.