The purpose of the Gas Thermometry experiment is to construct a temperature scale and determine the absolute zero temperature. This experiment demonstrates the temperature dependency of the pressure of a constant gas volume. In addition, the absolute temperature scale is determined by extrapolation towards low temperatures. The temperature readings given by a gas thermometer are nearly independent of the substance used in the thermometer. Generally, gases used in gas thermometry are Ideal Gases.
The apparatus consists of a table with three reservoirs beneath. The left reservoir contains boiling water and is connected to a variac that controls the power. The middle reservoir contains a polypropylene cylinder placed into a large Styrofoam block for insulation and contains a near equilibrium mixture of ice and water. The right reservoir is also a polypropylene tube in a Styrofoam block but this tube contains liquid nitrogen. Each of these reservoirs acts as a stable temperature reference and are accessible through a flange covering a hole in the table.
The main piece of the apparatus is a dipper which consists of a steel gas vessel attached to valves and tubing and mounted to a Lexan sheet (to prevent splashing/steam/vapor and to protect the manometer), a digital manometer and a handle. The dipper is designed to fit into each reservoir and rest on the flange on the lexan sheet.
The manometer has a digital readout screen. It is suggested you use Torr or mmHg as your unit of measurement, but it is not necessary if you make the appropriate conversions. Note that like most pressure gauges, the manometer reads in gauge pressure. This means pressure relative to the outside atmosphere.