Chem 152 - Lab 3 - Thermodynamics 1

Chem 152 - Lab 3 - Thermodynamics 1 - NAME and ID Number:...

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LAB PARTNER: Chris Luong Quiz Section: Total Points = 60 pts Notebook: No points are specifically assigned to your notebook for this lab, however, your TA may deduct up to 5 points for notebook pages that are disorganized, difficult to read, or do not contain complete data and observations. PURPOSE AND METHOD DATA AND CALCULATIONS A: HEAT CAPACITY OF THE CALORIMETER Run 1 Run 2 Run 3 Voltage, V (J/C) 2.3 2.3 2.3 Current, A (C/s) 2.85 3.04 2.97 Time (s) 118.75 136.32 146.69 24.7 24.7 24.2 28.9 28.8 28.2 *Eletrical power input into calorimeter (q), J 778.4 953.1 1002.0 185.33 232.3 250.51 5 pts 241.4 Standard Dev 9.1 Help In Excel type "=average(range of values)" Instead of entering a range, just click at one end of the values and drag mouse to the other end For standard deviation, in Excel type "=stdev(range of values)". NAME and ID Number: Alice Meng-Ju Hsieh 0734371 Initial temperature, o C Final temperature, o C *Calorimeter Constant, C cal, J/ o C Average, C cal Our goals are to: i) Determine the heat capacity of the calorimeter ii) Measure the heat of fusion of ice iii) Measure the heat of neautralization iv) Determine the enthalpy of hydration magnesium sulfate. Explain how each of these is accomplished in this experiment . (2 pts each = 8 pts): i). To determine the heat capacity of the calorimeter, several values need to be measured - voltage, current, time, initial and final temperature. The initial and final temperature allows us to find the change in temperature. To find the heat capacity of the calorimeter, we need to calculate the amount of heat added first. The equation is given by: qcal = current x voltage x time. Current is measured in amps, voltage is measured in volts while time is measured in seconds. In this lab, we assume that the amount of heat added into the system is equal to the amount of heat absorbed by the calorimeter because there is no heat loss. Then, we can calculate the heat capacity of the calorimeter by the euqation "Ccal = qcal / delta T". ii). To measure the heat of fusion of ice, we need to know the amount of heat that took place. We need to find the total heat lost by the calorimeter. Also, we know that ice melting is an endothermic reaction, thus heat is absorbed by the system. There is an equation given in the pre-lab introduction to find ∆Hfusion. q = Ccal∆Tcal = (mass of ice)(∆Hfusion) + (mass of ice)(specific heat of water)(∆Twater that was ice) Keep in mind that specific heat of water is 4.184J/g˚C. iii). In order to measure the heat of neutralization, we need to know the number of moles of the substance and the heat released by the system.
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This note was uploaded on 10/27/2010 for the course CHEM 152 taught by Professor Chiu during the Spring '08 term at University of Washington.

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Chem 152 - Lab 3 - Thermodynamics 1 - NAME and ID Number:...

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