Physics Thermodynamics Lab - Essay Example

?Your Full Your Thermodynamics Physics Thermodynamics Lab Video The experiment done aimed to prove the efficiency of the equation E = mc?T by measuring the temperature change of an ice water and hot water system with the calculated temperature using the equation mentioned (Sabbagh, youtube.com). Specific heat is the quantity of energy, in the form of heat that is needed to raise one unit mass of a substance by one temperature degree, either by Celsius or Kelvin. This equation however, is not applicable to systems involving a change in phase (“Specific Heat”, gsu.edu). Materials Approximately 40mL of ice water was measured and weighed, and the initial temperature was taken. On a separate graduated cylinder, 20mL of hot water was measured and weighed, and its initial temperature was also recorded. The ice water and hot water were mixed in a cup and the final temperature after the mixing was measured (Sabbagh, youtube.com). Results and Calculation Four trials were done during the experiment. Table 1 presents the data gathered (see table 1). The theoretical temperature was calculated using the following equations: Heat gained by ice H2O = Heat loss by hot H2O (Eqn 1) Heat loss = m x c x change in T = 4.186 J/g-?C x m (grams) x (initial T – final T) (Eqn 2) Heat gained = m x c x change in T = 4.186 J/g-?C x m (grams) x (final T – initial T) (Eqn 3) Table 1 Results Obtained Trial 1 Trial 2 Trial 3 Trial 4 Mass of ice H2O 39g 39g 39g 39g Mass of hot H2O 21g 19g 20g 19g Temp of ice H2O 12.2?C 16.9?C 16.3?C 16.9?C Final Temp after mixing 34.0?C 35.8?C 35.4?C 34.8?C Actual Temp of hot H2O 73.6?C 71.6?C 72.2?C 72.7?C Theoretical Temp of hot H2O 74.49?C 74.59?C 72.65?C 71.54?C % error 1.20% 4.18% 0.61% 1.59% Source: Sabbagh, A. “Physics Thermodynamics Lab.m4v”. You Tube. 18 Jan 2011 Using the equations stated earlier, the theoretical temperature of hot water for Trial 1 was computed in the following manner (Sabbagh, youtube.com): Heat gained by ice water = Heat loss by hot water mass (ice H2O) x c x (Initial Temp – Final Temp) = mass (hot H2O) x c x (Final T – Initial T) (39g) x (4.186 J/g-?C) x (12.2?C – 34.0?C) = (21g) x (4.186?J/g-?C) x (34.0?C – X?C) X = Theoretical temperature of hot water = 74.49?C The rest of the trials were also calculated using the same equations. The percent error was used to compare the theoretical hot water temperature with the actual temperature that was measured in the experiment. So for trial 1, the percent error was calculated in this manner: % error = (actual – theoretical) / theoretical x 100 = |(73.6?C – 74.49?C)| / 74.49?C x 100 % error = 1.20% The experiment done by Sabbagh, et al (youtube.com) was able to prove the experimental applicability of the equation for specific heat using the ice water-hot water system, and they were able to get an average 1.20% error in the four trials that have been conducted. Thermodynamics Equilibrium The first law of thermodynamics deals with energy conservation of a system at equilibrium, most commonly, energy is expressed as heat. It states that the change in internal energy is the difference between the heat supplied to the system and the work that was done (“First Law of Thermodynamics”, gsu.edu). This law then governs the transfer of heat in a system at equilibrium, from a system with high temperature to the system with lower temperature (“Heat Transfer”, gsu.edu). In this experiment, a gaseous system in equilibrium was investigated, with changes dictated on the temperature and the number of particles present in the system. The changes that were done were observed and recorded. First Experiment. Write down the initial temperatures for each of the two chambers. The initial temperature of the left chamber was 150?C, while the right chamber had a temperature of 750?. What do you think the final equilibrium temperature will be? I expect the final equilibrium temperature to be approximate 450?. Why are there more particles in the cold side than the warm side when you first start mixing the chambers? There are more particles in the cold side than the warm side when first mixing was started because the high pressure at the warm side brought about by the higher temperature pushes the particles to the chamber that reduces the pressure of the system. How long does it take for the temperature to equilibrate? The system reached equilibrium approximately 2 minutes and 14 seconds. After equilibrium is reached close the chamber door and raise the temperature in the right chamber to 900?. Reopen the chamber to determine the new equilibrium temperature. After raising the temperature of the right chamber to 900?, the new equilibrium temperature of the system was 671?. Second Experiment Write down the initial temperatures for each of the two chambers. The initial temperature of the left chamber was 500?C, while the right chamber had a temperature of 400?. What do you think the final equilibrium temperature will be? The final equilibrium temperature is expected to be approximately 450?. Will this system take a longer or a shorter time to equilibrate than the previous one? It is expected that the system will take a shorter time to reach equilibrium. Actual time of the experiment to reach equilibrium was 1 minute 25 seconds. Third Experiment Write down the initial temperatures for each of the two chambers. The initial temperature of the left chamber was 200?C, while the right chamber had a temperature of 100?. What do you think the final equilibrium temperature will be? The final equilibrium temperature is expected to be 150?. Will this system take a longer or shorter time to equilibrate that experiment 2 which had the same temperature difference as this one? It is expected that this system will take the same amount of time as the system in experiment 2. However, the actual time it took for equilibrium to be reached was 4 minutes 21 seconds. Fourth Experiment Write down the initial temperatures for each of the two chambers. The initial temperature of the left chamber was 150?C, while the right chamber had a temperature of 750?. Write down how many particles are in each gas initially. The left chamber contained 50 particles while the right chamber had 200 particles. Will this system reach equilibrium faster or slower than it took in the First Experiment with the same temperature difference? It is expected that this system will reach equilibrium faster than that of the first experiment. Compare the rate of temperature change on the left and right sides. Why are they so different? The rate of temperature change on the left and right sides are very different because there are more particles with higher temperature that moved from the right side causing the rapid increase in temperature of the system at the left side. Time how long it takes for about 125 particles to exist in each chamber and note the temperature difference the first time this occurs. It took approximately 10 seconds for the system to contain 125 particles on each side. With the same number of particles, the left chamber had a temperature of 544? while the right chamber had a temperature of 715?. Conclusion The experiment on the first law of thermodynamics showed that the change brought about by an increase or decrease in temperature causes the system to react in a manner that contradicts the effect of the change. Heat transfer proved to be experimentally true because the shift in the temperatures from experiments 1 to 4 showed that the heat moved from the higher temperature to the lower temperature chamber. The effect of the amount of particles in the chambers also showed that any imbalance on a system pushes the system to achieve a different equilibrium where there is still conservation of heat or energy. Comparison of experiments 1 and 4 showed that even if both systems have the same temperature conditions, the third variable, which in this case is the number of particles, also affects the equilibrium because of the presence of more particles that absorb heat. Hence the internal energy of the system before the chambers were opened was not in equilibrium and caused the shift when the chamber was opened. Works Cited Bothun, G. “Thermodynamic Equilibrium”. jersey.uoregon.edu. n.d. Web. 26 Mar 2013. “First Law of Thermodynamics”. gsu.edu. n.d. Web. 29 Mar 2013. “Heat Transfer”. gsu.edu. n.d. Web. 29 Mar 2013. Sabbagh, A., Rothman, A., Best, L. and Lord, C.“Physics Thermodynamics Lab.m4v”. You Tube. 18 Jan 2011. Web. 28 Mar 2013. “Specific Heat”. gsu.edu. n.d. Web. 26 Mar 2013. Read More