Klarinet Archive - Posting 000280.txt from 1999/12

From: Tony@-----.uk (Tony Pay)
Subj: Re: [kl] klarinet Digest 10 Dec 1999 09:15:01 -0000 Issue 1894
Date: Sat, 11 Dec 1999 00:06:24 -0500

On Fri, 10 Dec 1999 09:40:07 -0500, 100012.1302@-----.com said:

> Message text written by INTERNET:klarinet@-----.org

> > Come to think of it, Roger may have had it right after all. Does
> > "index" translate to "exponent?"
>
> Yes it does.
>
> > Roger: "7.0 - that's the index (with sign changed) of the square
> > root of the dissociation constant of pure water"
>
> > Bill: "negative log of 10e-14"
>
> > Are they the same thing? Anyone speak both British and
> > American chemistry?
>
> Square root isn't the same as logarithm. But as you both say, 7 is
> neutral water.

I *think* that the point is that the dissociation constant is the
*product* of the hydrogen ion concentration and the hydroxide ion
concentration, and for water at some standard temperature this is equal
to 10^-14 where the symbol ^ stands for exponentiation. The square root
comes in because the hydrogen ion concentration and the hydroxide ion
concentration are equal for water, each therefore being 10^-7 (the
square root of 10^-14).

Then the pH of water, being the negative log to base 10 of the hydrogen
ion concentration, is 7.

I believe that this relationship is sometimes written in terms of the
exponents, and so additively rather than multiplicatively, as

pH + pOH = 14

We do in fact sometimes call exponents 'indices' in UK, so that figures.

Why did you say you were wrong, Roger? Or am I misunderstanding you?

Tony
--
_________ Tony Pay
|ony:-) 79 Southmoor Rd Tony@-----.uk
| |ay Oxford OX2 6RE GMN family artist: www.gmn.com
tel/fax 01865 553339

... Madness takes its toll - please have exact change

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