Practical Wizardry

A Guide to Wizardry 

Experiments in Physical Chemistry. 1967. 2E. David P. Shoemaker. Carl W. Garland. (MIT professors.)

I notice this book every time I pass by it in the university library. With that title and retro cover, it looks so bad-ass and wizarding. Today, I resolved to explore its contents.

The authors present examples of chemistry theory that an undergraduate scientist can quantify by experiment. Formulas are manipulated into a form that can be replicated in a physical setup. Suitable apparatuses are illustrated and described. Then the experimental procedures are explained.

Now Look Here, Son ...

The great thing about this book is how it detailed it is with first-hand knowledge on how to conduct the experiments in practical terms. The directions are not skimpy overviews, like 'set the pressure to X and record the temperature'. They're navigation charts through deceptive and treacherous waters. 'Listen carefully to what you need to do, if you don't want to end up a sorry sod!'

"For the initial equilibration of the system, close the needle valve and adjust the main gas supply valve until the regulator gauge reads about 40 psi.

Then very slowly open the needle valve until the pressure in the system (as indicated by the manometer) is increasing at about the rate of 5 cm Hg min-1. Continue to adjust the needle valve until delta_p is about 75 cm (this should take at least 15 min).

If the gas pressure is increased rapidly at the beginning, the coil will not be able to bring the initial surge of gas to bath temperature, and the porous frit will be cooled to below its steady-state value; this will cause a very slow (2 to 3 hr) attainment of the steady-state value of delta_T. With care in making all pressure changes, a steady state should be achieved in about 40 min."

Joule-Thomson Effect. 59.

The Right Advice Makes All the Difference 

I can just imagine the poor soul who tried this experiment without such experienced guidance, thinking he is a complete failure as a scientist. It has happened to me countless times in physics labs!

He sees his data is completely off, since he didn't know he needed to wait the full THREE HOURS for his experiment to reach steady-state! Never mind he couldn't afford that luxury of time even if he knew. Until you try the experiment for yourself, you can't foresee the importance of these details!

What a difference experience makes: three hours vs 40 minutes! To scientific theory, the two experiments are carried out the same, but to the conductor of the experiments one is a baffling dismal failure and the other is an enviable success!