An Exercise in Freezing Point Depression

Part A. Determination of the Calorimeter ConstantRefer to Experiment 5 for a sample calculation of a calorimeter constant. Yourcalorimeter is not perfectly insulating; that is, a small amount of heat is either absorbed orreleased by the calorimeter each time you run an experiment. The amount of heat gainedor lost by the calorimeter per degree change in temperature is called the calorimeterconstant. It is the heat capacity of your calorimeter. You will determine this constant bymixing warm water with cool water in your calorimeter.1. Using your small graduated cylinder, measure approximately 5 mL of cool water(approximately 10°C – you may use the water from your ice bath used in thecalibration of your temperature sensor) and record its volume to the nearest 0.02mL. Pour the water into a calorimeter well. Using a clamp place the temperatureprobe into the well such that it is reading the temperature of the water but is nottouching the sides or bottom of the well.2. Go to the “set up run” menu and adjust the run to 5 minutes with a sampling rate of60 samples per minute. Begin the run and then quickly, using the same smallgraduated cylinder as before, measure approximately 5 mL of hot water (about 30 -35°C) from the hot-water tap and record its volume to the nearest 0.02 mL.Immediately before mixing the two solutions read and record the initial temperatureof the hot water using the digital thermometer.3. Pour the hot water into the well and stir until the temperature stops rising. Click onthe stop run button. To obtain the initial temperature of the cold water, use themouse to highlight the portion of the graph immediately prior to the addition of thewarm water and then click on the “stat” button (a box will appear that will give youthe average temperature of the water for the portion of the graph you highlighted).Repeat this procedure to obtain the maximum temperature reached. This is the finaltemperature of the solution. Record these initial and final temperatures in yournotebook. For all temperature measurements, do not rest the probe on the bottomof the flask!10-10