# Physics 312, Extra Credit for Week #9: due May 13, 1998, at 5 PM

Check the purity of your jewelry.

This project may be done by teams of 1-2 individuals. You must design an experiment that allows you to measure directly the specific heat capacity of a piece of jewelry. Perhaps the lecture notes from this week will give you some ideas on how to build a calorimeter. It isn't necessary to make an container which never touches the walls of the outer container ... just try to minimize the area of contact. Styrofoam cups are reasonably good insulators.

The goal is the measure the heat capacity of an object made of some metal, then compare that to the expected heat capacity of the metal. If the two match precisely, then the object is probably a pure sample of the metal. If the two are significantly different, then the jewelry may be an alloy of some precious metal and a common one (such as copper or tin).

If you don't have any gold or silver jewelry, you may use any small metallic object. But make sure that you know the primary metal from which the nail is made!

You'll need to measure very carefully the mass of the jewelry, fluid, and inner container of the calorimeter. Perhaps you could use one of the scales in the Physics Department to make these measurements. You'll also need a good thermometer, in order to measure the starting temperature of the calorimeter, the starting temperature of the jewelry, and the final temperature of the whole system. The hotter you can make the jewelry, the larger the change to a final temperature. But don't melt it!

Describe carefully the calorimeter you design and build. Include a drawing of the finished system, and indicate the cost of each item. Measure the object's size and mass, and do the same for any extra weights and other apparatus in your experiment.

Submit a report which contains the pictures and descriptions of your experiment, as well as the results. You may also include interesting items you discovered during the course of the procedure.