Fall 2008

A few experiments of this kind actually performed by himself will give the student a more intelligent interest in the subject, and will give him a more lively faith in the ex-actness and uniformity of nature, and in the inaccuracy and uncertainty of our observa-tions, than any reading of books, or even witnessing elaborate experiments performed by professed men of science.

Reading Assignment

Maxwell, J. C. 2001, Theory of Heat, Dover Publications. Ch. 3.

Scientific terms and concepts

1. calorimetry2. tacit3. method of cooling4. interstices5. indium6. method of mixture7. quicksilver8. capacity of heat9. specific heat

10. specific gravity11. counterpoise12. grain13. latent heat14. imponderable15. fusion16. evaporation17. condensation18. latent heat of expansion

Homework exercises

1. Specific heat of copper problem (from Adkins, 3.7) In a certain calorimetric experiment designed to determine the specific heat capacity of copper, 0.1 kg of the metal at 100 deg. C is added to 0.0002 cubic meters of water at 15 deg. C which are contained in a thermally insulated vessel of negligible thermal capacity. After the mixture has reached equilibrium, the temperature is found to be 18.8 deg. C. If the heat capacities of copper and water are essentially constant over the range of temperatures concerned, what is the specific heat capacity of copper? Is this experiment performed at constant pressure or at constant temperature?

2. Latent heat of melting problem On page 70, Maxwell describes how two experiments can be per-formed in succession in order to determine the latent heat of steam condensing into water. Suppose we adapt this method so as to determine the latent heat of ice melting into water. In particular sup-pose that instead of 100 grains of steam condensing, you allow 100 grains of ice at zero C to melt in a 5000 grain bath of water initially at 55.0 degrees C. The temperature at the end of the experiment is 52.3 degrees C. For the second experiment, we add 1000 grains of 5 C water (instead of ice) so as to cool a 5000 grain bath of water initially at 56.0 degrees C. The final temperature is 45.8 degrees C. Now, how much heat does each grain of ice absorb in order to melt?

Week 3: Calorimetry

Thermodynamics- Week 3, Fall 2008 1