Chem152_Thermo1_Report

Chem152_Thermo1_Report - NAME and ID Number: Quiz Section:...

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NAME and ID Number: LAB PARTNER: Quiz Section: Total Points = 60 pts PURPOSE AND METHOD DATA AND CALCULATIONS A: HEAT CAPACITY OF THE CALORIMETER Run 1 Run 2 Run 3 Voltage, V (J/C) 4.8 4.7 4.8 Current, A (C/s) 3.26 3.38 3.34 Time (s) 186.60 123.31 180.37 23.1 23.0 23.6 31.4 29.5 31.4 *Eletrical power input into calorimeter (q), J 2920 1959 2892 5 pts 352 301 371 341 Standard Dev 36 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 STD = standard deviation, (in Excel type "=stdev(range of values)") 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 This will be determined by measuring the temperature change that happens when some predetermined amount of heat is added to a calorimeter. We will add heat electrically. The energy is determined by: Energy(J) = Current (C/s) X Voltage (J/C) X Time (s) Since the heat generated by the electrical heating is equal to the heat gained by the calorimeter, the heat capacity of the calorimeter is the heat gained by the calorimeter divided by the temperature change. The equation we will use to determine the Heat capacity of the calorimeter (Ccal), is: Ccal= qcal/ temperature ii) Measure the heat of fusion of ice The heat of fusion is the energy required to convert ice into liquid water. To find the head of fusion, we need to separate into two parts: Heat lost by the calorimeter and the heat gained by ice/water. The equation we will use to find the heat lost by the calorimeter is: -q= -Ccal* ∆Tcal. Where ∆Tcal = Tfinal-Tinitial The Equation that we will use to find the heat gained by ice/water is: q= (Mice)(∆Hfusion) + (Mice)(4.184 J/g*C°)(∆T water that was ice) Where ∆T water that was ice= T final- T icecube. Set q=-q and you will have two unknowns: ∆Hfusion and Mice. The mass of ice can be determined using simple alegebra so find ∆Hfusion. iii) Measure the heat of neautralization The net ionics for the neutralization of HCl and NaOH and the acetice acids are exothermic. We will use q=Ccal∆T to determine the magenitude of the heat released. The initial temperatures will be measured for each of the acids and bases before the mixing. The Ccal value will be assumed to be the same values
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This note was uploaded on 04/07/2008 for the course CHEM 152 taught by Professor Chiu during the Spring '08 term at University of Washington.

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Chem152_Thermo1_Report - NAME and ID Number: Quiz Section:...

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