HEAT ENGINE/ GAS LAW APPARATUS

Transcription

1 nstruction Manual and Experiment Guide for the PSCO scientific Model TD-8572 HET ENGNE/ GS LW PPRTUS ' a1 "~.J" Foothil/s Blvd. Roseville, C US ""..! r--llrl ' Phone (916) ' FX (916) web: bel/ar waysto teach science

2 C Heat Engine/Gas Law pparatus ntroduction The P SCO TD-8572 Heat Engine/Gas Law pparatus is used for quantitative experirnents involving the deal Gas Law (as described below) and for investigations ofa work:ing heat engine. The equipment allows the amount ofwork done by thermal energy to be measured. Equipment The heart ofthis apparatus is a nearly friction-free pistonl cylinder system. The graphite piston fits snugly into a precision-ground Pyrex cylinder so that the system produces almost friction-free motion and negligible leakage. mass platform for adding a load to do work experiments li precision-bore pyrex cylinder inside a protective plastic shield ~ piston-holding thumbscrew millimeter scale for measuring piston displacement The apparatus incudes the following equiprnent base apparatus (Figure 1) - piston diameter: 32.5 mm ± mass ofpiston and platform: 35.0 g ±.06 air chamber (Figure 2) 3 hose configurations: one with one-way check valves and one with a clamp (Figure 2), and one plain piece oftubing (not shown) 1 each, one-holed and two-holed rubber stopper./ tubingfor./ connecting chamberto cylinder two port sh ut-off valves Figure 1. Base apparatus The Heat Engine/Gas Law pparatus is designed with two pressure ports with quick-connect fittings for connecting to the air chamber tubing. The apparatus can be connected to a Low Pressure Sensor for use with P SCO computer interfaces. Do not apply lubricant to the piston or ~ cylinder. Do not immerse the base apparatus in liquido Note: Use only non-caustic/non-toxic gases such as air or helium. one-way check valves pressure port mating connectors Figure 2. ir charnber and tubing lways release the tubing clamps prior to storage to avoid permanently deforming the tubing. Maxirnum Pressure: 345 kpa.

3 J4C Heat Engine/Gas Law pparatus Experiment 1: Operation ofa Heat Engine Eq uipmentrequired: Heat Engine/Gas Law pparatas container ofhot water gmass.. container ofice water Equiprnent Setup (j) Using the one-holed stopper, connect the tubing with the one-way valves to the air chamber and to a connecting pon on the base assembly. (lj Close the shut-offvalve on the tubing from the ullused Set a mass of 100 to 200 g on the mass platform. Close lhe shul-off valve on lhe tubing from lhe unused porto,... Note: Use a maximum mass of200 grams in the experirnent. larger mass will cause the valve seals to leak. (j) Move the air chamber from an ice water bath to a hot water bath. You will note that the air in the chamber quickly expands through the tubing and moves the piston up. Note also that the one-way check valve in the tubing connecting the base apparatus and the air chamber pernuts air to enter the cylinder, while the other one-way check valve prevents air from leaving through the branched tube. direclion of airflow Figure 1.1. Setup for the Heat Engine Move the air chamber back to the cold bath and note that externai air is sucked into the air chamber through the one-way valve located at the end ofthe branched tube. Note also that the one-way valve in the connecting tube prevents the air from escaping from the piston, so the height ofthe piston remains the same. Repeat steps 3 and 4 until the mass has been completely lifted.,... Note: The greater the temperature differential between the hot and cold water baths, the greater the lift achieved through each cycle through them. 3

4 ~ -----~ ~ ~-- --~-~ ~ --~~ C Heat Engine/Gas Law pparatus Experiment2: Charles' Law Equipment Required: Heat Engine/Gas Law pparatus container ofhot water. thennometer. ice Theory Charles' law states that at a constant pressure, the volume ofa fxed mass or quantity ofgas varies directly with the absolute temperature: V=cT (at constant P and where Tis expressed in degrees Kelvin) Setup (j) Using the one-holed stopper and plain tubing, connect the base apparatus and the air chamber. Ql Close the shut-off valve on the tubing from the unused porto Tum the base apparatus on its side. (n this position, the force acting on the apparatus is the atmospheric pressure and is equal throughout the range of operation ofthe piston.) Close the shut-off valve on lhe lubing from lhe unused porto dd ice... Do nol allow lhe lip of lhe lhermomeler lo louch lhe botlom of lhe conlainer. Hot CD Place the air chamber in a container ofhot water. fier the chamber equilibrates to the temperature, record the temperature and the height ofthe piston. Ql dd ice to the container and record the temperature and pressure at regular time intervals. Calculate the gas volumes at the various piston positions you measured and make a graph ofplots oftemperature versus volume. (Hint: The diameter ofthe piston is 32.5 llli11.)

5 C Heat EngineiGas Law pparatus Experiment 3: Boy/e's Law Theory EquipmentRequired: Heat Engine/Gas Law pparatus. Science Workshop computer interface*. Pressure Sensor (C-6532) *For details on setting up and operating the Pressure Sensor with Science Workshop, please consult the instruction sheet for the Pressure Sensor and the User's Guide for Science Workshop. Boyle's law states that the product of the volume of a gas times its pressure is a constant at a fixed temperature: PV a Therefore, at a fixed temperature, the pressure will be inversely related to the volume, and the relationship will be linear: a p v Setup CD With the platform raised to its uppermost posi tion, connect the Pressure Sensor to a port on the base apparatus with a short piece of tubing (Figure 3.1). Cf) Close the shut-offvalve 011 the tubing from the u11used port. G) Connect the Pressure Sensor to the computer interface and set up Scie11ce W orkshop to record pressure. Be sure that you set up the keyboard sampling option so you can enter height data by hand. (Consult the Science Workshop User 's Cuide, "Keyboard Sampling," for details.) to compuler inleliace Close the shut-off valve on lhe lubing from lhe unused pari. () Record the height of the piston and the pressure when the platfbrm is raised to its highest position. Cf) Press the platform down to a series oflevels and record the height and pressure at each leve. Pressure Sensor G) Convert the height measurements to gas vohune Figure 3.1. Experimental setup measurements. (Hint: The diameter ofthe piston is 32.5 rum.) Prepare a graph ofpressure versus volume.,... Note: The relationship between pressure and volume may not be linear at pressures greater than 120 kpa because ofair leakage from the valves and ports at higher pressures. 7