Measurement 1

Date Performed: Name: Date Submitted: Partner: Instructor: Measurement 1 Objective To measure temperature changes in water, become familiar with common laboratory equipment, make a good laboratory notebook record, and write a lab report. Experimental Data Part A Temperature Changes Part B Mixing Hot and Cold Water Calculations of Hot and Cold Water Sample Calculation Correction factor =21.48 - 22.00?C =-0.25?C Density at 68.60?C =0.9806 - 0.9778 =0.0028 density range =65 - 68.60 =-3.6 density reduced in proportion =0.9806 - 3.6 x (0.0028) 5 =0.9786 g/mL Mass of 50.00 mL of Water at 68.60?C =0.9786 x (50) =48.93 g ?T Hot =T Hot ? T Final ?T Cold =T Final ? T Cold gH?TH = (mass of hot water) x ?T Hot gC?TC = (mass of cold water) x ?T Cold Results and Conclusions The temperature change in water of Part A is concluded to be -40.00?C for the temperature of water in the beaker and -43.66?C for the temperature of the water in the polystyrene cup, over a 60 minute period. The graph in Part A contains two exponential lines instead of two linear lines because the change in temperature is not a linear function. The two lines are coincident and never cross one another. The polystyrene cup acts as an insulator and can trap heat more efficiently than the glass beaker. Therefore, the temperature of the cup will be above that of the beaker during a 60 minute period. Water cools more quickly in glass containers than polystyrene containers over a period of time. Results for Part A: The temperature change in Part B is concluded to be-28.90?C after adding 40.00 mL of water in total. The gH?TH ? gC?TC after adding 40.00 mL of water to the boiled water in the polystyrene cup. This result is not in good agreement with the accepted value. Results of Part B: The T Hot (?C) gives the temperature of the hot H2O in the cup before adding 10 mL of the cold water. T Cold (?C) gives the temperature of the cold H2O in the cup which is added in 10 mL intervals to the hot water. T Final (?C) gives the temperature of the H2O after the cold water is added. The ?T Hot (?C) gives the change in temperature of the hot H2O from its T Hot minus its T Final. ?T Cold (?C) gives the change in temperature of the cold H2O from its T Final minus its T Cold. gH?TH (J/g??C) gives the specific heat of the hot water; it is the mass of hot water times its temperature change. gC?TC (J/g??C) gives the specific heat of the cold water. It is the mass of cold water times its T change. The last two columns of the table above should display the same value for each pair of gH?TH and gC?TC. The values of gH?TH do not follow a trend, the value decreases (till step 3), and increases (to step 5). The values of gC?TC however follow a trend, as it continually increases throughout every step. Discussion of Experimental Uncertainty The accepted value is gH?TH = gC?TC. According to the Law of Conservation of Energy, the heat lost by the hot water should equal the heat gained by the cold water. In this experiment the values will not be equal because the experiment was not conducted in a closed system. Sources of experimental uncertainty include the environment in which the experiment was conducted. Excess heat could have been given off, or the temperature of the room adversely affected the temperature readings leading to the unaccepted value. Graphs The Affect of Time on Temperature Time (mins) 0 5 10 15 20 25 30 35 40 45 50 55 60 T of H2O in Beaker (?C) 62.00 49.00 43.00 37.00 35.00 32.00 29.00 27.00 26.00 25.00 24.00 23.00 22.00 T of H2O in Cup (?C) 66.64 52.05 46.87 41.50 38.11 35.41 32.41 30.39 28.63 27.15 25.82 24.43 22.98 The Affect of Added Volume on Temperature Step Volume in Cup (mL) Volume Added (mL) Initial T (?C) Final T (?C) 1 50 10 68.60 56.15 2 60 10 56.15 48.60 3 70 10 48.60 45.35 4 80 10 45.35 42.47 5 90 10 42.47 39.70 The Affect of Time on Temperature Time (mins) 0 5 10 15 20 25 30 35 40 45 50 55 60 T of H2O in Beaker (?C) 61.48 48.48 42.48 36.48 34.48 31.48 28.48 26.48 25.48 24.48 23.48 22.48 21.48 T of H2O in Cup (?C) 66.64 52.05 46.87 41.50 38.11 35.41 32.41 30.39 28.63 27.15 25.82 24.43 22.98 The Affect of Temperature on Specific Heat step mass of hot water (g) mass of cold water (g) T Hot (?C) T Cold (?C) T Final (?C) ?T Hot (?C) ?T Cold (?C) gH?TH (J/g??C) gC?TC (J/g??C) 1 48.93 9.98 68.60 23.00 56.15 12.45 33.15 609.18 330.84 2 59.12 19.95 56.15 23.00 48.60 7.55 25.60 446.36 510.72 3 69.21 29.93 48.60 23.00 45.35 3.25 22.35 224.93 668.94 4 79.21 39.90 45.35 23.00 42.47 2.88 19.47 228.12 776.85 5 89.21 49.88 42.47 23.00 39.70 2.77 16.70 247.11 833.00