Archive for September, 2009

Happy Days

Monday, September 14th, 2009

Here’s a picture of Cate having a Happy Day at Broadway at the Beach.

Ayyyyyyyyyyy!  (800x600 JPEG, click to enlarge)

Ayyyyyyyyyyy! (800x600 JPEG, click to enlarge)

Broadway at the Beach has added a bunch of old rides from the Pavilion and called it the Pavilion Nostalgia Park. While i never went to the Myrtle Beach Pavilion while it was open, the rides do remind me a lot of what you could ride at the county fair when I was a little kid.

Disinfected

Thursday, September 10th, 2009

There’s a reason I never leave my food unattended around students:

The teacher had stepped away from her desk for a few moments around 3:30 p.m. Sept. 2. After returning, she drank her tea and noticed it had a “peculiar taste,” according to a York County Sheriff’s Office report.

The taste of … hand sanitizer.

At the time of the incident, five students were in her classroom waiting on a school bus, the report stated. The students told the assistant principal and school resource officer they didn’t see anyone put anything in the teacher’s drink.

Of course they didn’t see anything.  And whichever one put the sanitizer in this teacher’s drink just wanted to make sure the drink had been disinfected.

Sodium peroxide

Tuesday, September 8th, 2009

I went looking through the chemicals the other day, and I decided that it had been too long since I recorded a good chemical demonstration video.

So I pulled out some sodium peroxide, Na2O2. The MSDS sheet looks interesting:

DANGER! CORROSIVE. STRONG OXIDIZER. CONTACT WITH OTHER MATERIAL MAY CAUSE FIRE. CAUSES SEVERE BURNS TO EVERY AREA OF CONTACT. HARMFUL IF SWALLOWED OR INHALED.

Also:

Contact with combustible, organic, or oxidizable substances may cause extremely violent combustion. May react explosively in contact with large amounts of water.

it’s a strong oxidizer, plus it reacts with water?  If there were ever a substance tailor-made for a cool reaction demonstration, sodium peroxide would have to be it.  So let’s see … what would happen if you took some sodium peroxide, sprinkled it on top of a few combustible cotton balls, and then added water?

No, really.  I’ve found this demonstration mentioned in several of my chemistry books. (Ever notice how the more impressive chemical demonstrations involve doing things the MSDS specifically warns against?)

The idea behind this particular demonstration is that the reaction of sodium peroxide with water will release hydrogen peroxide and quite a bit of heat.

Na2O2 + 2H2O –> 2NaOH + H2O2 … and lots of heat.

Under these conditions hydrogen peroxide also decomposes, releasing oxygen – which will speed up any combustion that happens to be occurring.

2H2O2 -> 2H2O+O2

In short, we get oxygen and a lot of heat.  This usually makes for a fun demonstration.  Take a look.

Looking a little more closely, you can see that after only a few seconds, the cotton catches fire.

The flame is bright orange, probably due to the presence of sodium ion in the flame.

The flame is bright orange, probably due to the presence of sodium ion in the flame.

And after several seconds more, the evaporating dish just can’t handle any more.

Bang!  You can't see it in the video, but there's a sand bath just below this evaporating dish - in case something like this were to happen.

Bang! You can't see it in the video, but there's a sand bath just below the evaporating dish - in case something like this were to happen.

… and this is why we always wear safety glasses when doing chemical demonstrations.  But perhaps I should have given the camera some safety glasses, too?