Friday, October 29, 2010

Lab Quote Friday #9

This week in lab the students were making alum from coke cans.  Alum is pronounced al-um, but students continually pronounced it like the shortened version of alumni.  Let's review:



Alum has some great uses.  You can read all about it here:

The importance of reading directions CAREFULLY:
The first step in the experiment is dissolving little aluminum pieces in boiling potassium hydroxide.  One group had a solution that was a different color than all the others.  The professor inquired about what they had used/done, but they claimed they had followed the directions.  Not long after, people in the lab started coughing a lot.  Turns out the group used concentrated sulfuric acid instead of potassium hydroxide.  Note: boiling concentrated sulfuric acid is NOT a good idea, reading directions carefully IS a good idea.

Later in the process, students get crystals to form by cooling their solution in an ice water bath.  If they have added too much liquid in earlier steps, they need to boil off some of the water or crystals will not form.  Here's a conversation I had:
Me:  You'll need to boil off some of your water before you move on to the next step.
Lab Girl:  Ok. 
  - She then proceeds to turn down the flame on her bunsen burner which causes it to go out. -
Lab Boy:  What did you do that for?
Lab Girl:  She told me to. 
Me:  I said you'll need to boil off some of your liquid, not turn off your burner.  "Boil off" means letting the solution boil so that the water evaporates and your volume decreases.
Lab Girl:  Oooooh, I get it.  I'm not too good with these scientific chemistry terms. 
Me (thinking only, of course):  You're probably not too good with simple cooking terms either!

Just a heads up- labs will be winding down over the next couple of weeks.  There will only be a one or two more lab quote Fridays before I take a break.  Labs will start up again mid-January.


Jeremy said...

I'll miss the lab quotes.

Alyson said...

So first of all, I'm surprised there aren't more tragic chem lab accidents with people boiling THE WRONG CHEMICAL and not using hoods and whatnot.

Secondly, I've always thought that good scientists generally make good cooks. They're practically the same thing.

Shelly said...

I don't understand how "boil off" and "turn off" can be interpreted as the same thing in any context! uuuugggghhhh...
I'll be sure to add you to my Friday prayer list. I'm going to pray for protection that your lab doesn't explode!!

Amanda said...

i love that they were boiling SULFURIC ACID! scary.