I have finished grading CHM 100 Test #1, and have posted the grades on Desire2Learn.  You may see your grades there now, or wait until Wednesday when I return the papers in class.

Update: 9/14/09 11:20 PM: I have finished grading CHM 110 Test #1, and have posted the grades on Desire2Learn.  You may see your grades there now, or wait until Wednesday when I return the papers in class.

If you’re a CHM 100 student, you might have noticed that a part of the oxygen lab that you didn’t get to do involved a compound called sodium peroxide.  Sodium peroxide (Na₂O₂) is nasty stuff.  It’s a strong oxidizer – which means that it’s dangerous to put into direct contact with anything that burns easily.  It also reacts violently with water.  So what does the lab manual suggest that we do with sodium peroxide?  Sprinkle it onto easily-burned cotton balls and then add water.

No, really.  That’s what the lab manual suggests.  And if you have the Flash plugin installed in your browser (you probably do), here’s what that would look like:

[flv:http://scienceattech.com/wp-content/uploads/2009/09/n2o2_1_lo.flv 320 240]

What’s happening?  The sodium peroxide reacts with water to make hydrogen peroxide and sodium hydroxide.  Plus, you get lots of heat.

Na₂O₂ + 2H₂O –> 2NaOH + H₂O₂

Then, the hydroegn peroxide formed in the first reaction decomposes to make oxygen.

2H₂O₂ -> 2H₂O+O₂

If you did the oxygen lab, you know what the presence of pure oxygen does to combustion!  it’s just too bad that no one told the poor evaporating dish.