Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Stop using calorie?



herbgottlieb@juno.com says:

Ludwik... I still do not understand how reference to calorimetry would
simplify your response to this unusual student. However, I do believe
that there is justification in teaching calorimetry as an outmoded
concept that has historical significance and has helped science progress.


I am tempted to wonder if you understand what 'calorimetry' means, at least
in the way Ludwik and many others are using it. 'Calorimetry' is the
measurement of changes in internal energy, usually* by the means of
measuring the temperature change of a object with known heat capacity (as
in a 'bomb calorimeter'). In its modern usage, 'calorimetry' has *nothing*
to do with 'caloric' the non-existant substance (except etymologically).

Now, to do Joule's paddle wheel experiment, you need to measure the work
done, measure the change in internal energy, and compare them. The second
step *is* calorimetry. I don't see any way around that.

In the context of Ludwik's unusual student, you would have to explain about
heat capacity related internal energy to temperature and so forth. That
is, you would have to teach them calorimetry; you might not call it that,
but a rose by any other name....

--
--James McLean
jmclean@chem.ucsd.edu
post doc
UC San Diego, Chemistry

* I say 'usually' because I believe that there are more complicated set ups
in use these days. A search on the WWW brought up pages on things like
'differential scanning calorimetry', whatever that is.