Showing posts with label chemistry. Show all posts
Showing posts with label chemistry. Show all posts

12 June 2009

Science Scouts

I'll admit I really only wanted to be in Girl Scouts for the badges.  Okay, and maybe the cookies.  Because you could get a badge for selling cookies!

So, much delight to come across this!

Here's my sash!





13 April 2008

Meteorologica

About a week ago, with the onset of April, we had our first taste of summer. Humid mornings, towering clouds swelling to afternoon thunderstorms, temperatures in the upper 80s. I wasn't prepared. Readying myself for open-toed shoes and sandals is hard enough, much less for short sleeves and skirts. Today, though, we had another dose of winter weather. That which passes for winter in Florida: grey skies, drizzle, temperatures barely climbing out of the 60s.

In today's (however brief) return of all-day rain, things just strike me as a little more vibrant than usual. That probably has more to do with the soaking showers we had a week ago, but without the bleaching of strong overhead sun, colors seem a bit more intense today. It reminds me of California. Before the winter weather patterns arrive, the hills turn golden brown in early summer and remain that way through most of the fall. Oh, t
here's moisture in the air - just barely enough to sustain some kind of dormancy - but no real rain for months. When the rains do come again, green spreads itself over the hills about a week later. I remember returning from Thanksgiving in Indiana one year to see the hills had greened up in our absence; on the long approach path into San Jose from the south that parallels the 101, such delight it was to see that color again. When it does return, it's like an old friend you haven't seen in a while. You don't realize how much you had missed him until he's in your presence.


In my chemistry classes, I teach that acid-base indicators have two forms, one color in the presence of a base and another color in acid. The transition color - a blend between the two, like orange between red and yellow - isn't a separate third form, it is an equilibrium of both colors. Does spring truly exist? Perhaps spring isn't its own season distinct from winter or summer, but instead, it is equal parts both. This swing from winter into summer and back to winter will be followed by summer again - I'm hoping for at least a few days before this happens. I'm grateful for a prolonged slide into summer, but I know this reaction will inevitably go to completion. I'd be lying if I said I didn't enjoy the overstuffed clouds and the lightning. But I'll wait patiently for October.

23 October 2007

Happy Mole Day


Don't forget to celebrate Mole Day today, from 602a to 602p.

And you can dress up like a mole, if you like. This has me wondering why I don't own this. ------>


05 June 2007

The Pedantic Chemist

or Splitting - not dissolving - Hairs.

Go Here and click "Watch our TV Commercial" over on the right-hand side. Watch; pay attention to the pH claim at the end.

Ten times lower pH than regular Nair, huh? Methinks the ad execs need a high-school chemistry refresher...

Those of you in the room who paid attention in chemistry class should recall that pH = -log[H+], where [H+] is the hydrogen-ion concentration of the solution. The more H ions, the more acidic the solution, the lower the pH. The log indicates that the pH scale is (wait for it) a logarithmic scale. That makes acidity/alkalinity easier to discuss by simply using the power of ten on the hydrogen-ion concentration, instead of tripping over scientific notation all the time. So that means that a solution with a pH of 5 (1 x 10^-5 mol/L) has ten times more hydrogen ions as a solution with a pH of 6 (1 x 10^-6 mol/L), and is thus more acidic. So. Every increment of 1 on the pH scale represents a tenfold change in hydrogen-ion concentration.

I think you see where I'm going with this.

A cursory check of The Internets shows that ordinary depilatory creams have a pH around 12. (The basic conditions help break down sulfur bonds in hair, effectively decomposing it.) So, if New Sensitive-Formula Nair does indeed have a pH that is ten times lower, that would put New Sensitive-Formula Nair at around 1.2 on the pH scale. Which is crazy acidic, and nothing I'd put on skin - sensitive or otherwise. It appears that New Sensitive-Formula Nair actually has a pH around 11, which corresponds to a hydrogen-ion concentration that is ten times lower.

The claim they make is really for hydrogen-ion concentration, not pH. But I suppose the non-chemist target audience is more likely to "understand" (read: have heard of) pH instead of "hydrogen ion concentration". Still. You can't have it both ways, kids. Please don't perpetuate bad math. If you'd just said "ten times less alkaline" or some such verbage, I wouldn't have called you out on it.

Everything you always wanted to know about depilatory chemistry but were afraid to ask.