Charles Law - Irwin [3296]

Irwin Charles Law. A clear simple way of demonstrating that the volume of a fixed mass of gas is proportional to its absolute temperature. It comprises a Jolly's apparatus on an anodised stand. A scale is marked in mm. Spring clips secure an air reservoir and adjustment is made using a vertical clamping rod. Comes complete with a leveling tube and Jolly air thermometer. Supplied with oil bead included. Thermometer -10 - 100°C. Height 33.5cm x width 40cm x depth 1.5cm. Does not use mercury as this is now deemed as a highly dangerous substance.

Instructions:

Fill a 400ml beaker with water, sit it on a tripod/gauze and then immerse the Charles’ Law Apparatus into the water so that the water level is about the 10mm position on the scale. It is advisable to hang the apparatus from a clamp rod mounted on a retort stand. A suitable hole is provided for this. Take a temperature reading and a scale reading from the bottom of the bead in the capillary bore. Heat the water using a Bunsen burner and take both readings every 30s. Plot a graph of length (volume) against temperature. Plot a line of best fit. You should get a straight line which intersects the volume axis. If you rescale the graph so that the temperature axis goes down to about - 300oC, you should be able to extrapolate the absolute zero of temperature. The straight line supports Charles’ Law demonstrating that volume of a gas is directly proportional to its temperature provided the pressure is kept constant. (In this case the pressure is atmospheric pressure). The Kelvin scale may then be introduced.

N.B. Before carrying out the experiment ensure that the base of the capillary tube is aligned with the zero mark on the base plate. If there is a small amount of oil at the base of the tube align the top of the oil mark to the zero mark.

The Irwin Charles’ Law Apparatus comprises a capillary tube, which is sealed at the bottom, showing a scale from 0 to 200mm. This is mounted onto a backing plate which also has a -10 to 100oC thermometer mounted alongside the tube. Due to movement of the oil in the capillary tube in transit, separation of the bead may occur.

Refill set also available as an optional extra (Code 80857).

Video Presentation available on the IPC Irwin website: http://www.ipcirwin.com/charles-law-apparatus