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Unformatted text preview: P251 Thermodynamics Lab 1 Physics 251 Laboratory Thermodynamics Part 1 Pre-Lab: Please do the pre-lab exercises on the web. Introduction It had been recognized by the 18 th century that the amount of heat, Q, required to change the temperature of a system is proportional to the mass, m, of the system and to the temperature change, T. This proportion is what we now know as specific heat and is often abbreviated by c. This value is valid for heat flow into or out of the system. This lab will help us see how to determine the specific heat of a known substance. Equipment/Supplies Calorimeter Unknown sample #2 Unknown sample #1 Thermometer Water Stirrer Graduated cylinders Paper towels Boiler Balance Section 1: Calorimetry Calorimetry is the quantitative measurement of heat exchange. When different parts of an isolated system are at different temperatures, heat will flow from the portion at higher temperature to the portion at lower temperature. If the system is completely isolated, no heat can flow into or out of the system, that is, the energy of the system is conserved. You can determine the specific heat of an unknown material by recognizing the First Law of Thermodynamics, in this case, Q sys lost = Q sys gained. The specific heat of water is 4190 J kg K / . The density of water is 1.0 g/cm 3 . The specific heat of the calorimeter is 910 J kg K / . Q sys lost is found by adding up all the Q=mc T from each object whose temperature decreases. Similarly, Q sys gained is found by adding up all the Q=mc T from objects whose temperature rises. 1. In the pre-lab exercise on the web you derived the formula to calculate the specific heat of an unknown object given its mass, m s , by adding it at temperature T a to a mass, m w , of water at T b and the system coming to an equilibrium temperature T f . Write this equation on your results sheet for use in section 2. P251 Thermodynamics Lab 2 2. Develop an experiment to determine the specific heat of an unknown sample using the...
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