Re: Chemistry 101

[lmittel@ibm.net (Larry Mittell)]

>  The
>equations are DeltaTf = m*Kf and DeltaTb = m*Kb where Kf is -1.86 (the
>cryoscopic constant) and Kb = +0.52 (the ebullioscopic constant) and m is
>the molality of the EG.  Molality is defined as the number of moles of
>solute per Kg of solvent.  A 50% solution (by weight not volume) of EG in
>water will freeze at -24 deg F or -31 deg C.  (These solutions are usually
>made by volume not weight and calculated temperatures will therefore be
>different.)  These numbers assume that the solute is a non-electrolyte (they
>don't form ions in solution).  The calculated temperature changes can
>approximately double or even triple when dealing with solutes which are
>electrolytes (the DO form ions in water).  The exact amount of this effect
>depends upon the number of ions produced per mole of solute.  For NaCl it
>will double.  For K2SO4 it will triple.  For Na3PO4 it will quadruple.  (As
>a first approximation.)

Thanks a lot, Myers.  I thought I'd got rid of them years ago, but your
message has brought them back. I'm having those nightmares about taking the
Chem Final without having studied for it.  Yechh!

Hasta luego,
Larry
87 5kcstq