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.