Charles’ Law and Absolute Zero
Date of experiment: November 4, 2010 Date submitted: November 11, 2010 Introduction: As per Charles’ Law, there is a linear relationship between the temperature and volume of a gas. Charles discovered that -273°C is the point at which a gas has no volume. Since that’s as cold as he thought things could ever get, that originated the idea of absolute zero.
In this experiment, Charles’ Law was applied and made into data to determine an experimental value for Absolute Zero. To do so, a fixed amount of gas was confined in a small, uniform sample tube.The temperature of the gas was changed, by being placed in water. The expected result is that as the temperature of the gas gets cooler (decreases), the volume of gas will decrease. Procedure: A 400mL beaker was filled with tap water and place on a hot plate until the thermometer read 55°C. Then a sample tube filled with two mercury plugs was obtained from the instructor. With a ruler, the distance between the two mercury plugs was recorded. Using small rubber bands, the sample tube was strapped to the ruler, which was then attached to the bottom of thermometer.A cork was attached onto the top of the thermometer, and then clamped in the beaker of pre-heated water. The initial temperature and distance between each plug in the pre-heated water were then recorded. Ice was added and stirred every so often to cool the temperature of the water. When the beaker was going to overflow, small amounts of the water were removed by a pipet. The temperature and distance between each plug were then recorded every two minutes. Eight sets of temperatures were recorded when the goal temperature of 0. °C was achieved. Data: 1) Temperature and Distance Between Mercury Plugs Every 2mins Time (minutes)| Temperature of water (°C)| Distance between plugs (mm)| 0 (Plugs out of water)| 49. 8| 60. 2 (in room temp)| 2 (Plugs in water)| 46. 3| 63. 8| 4| 42. 2| 63. 3| 6| 39. 3| 62. 2| 8| 24. 9| 60. 0| 10| 19. 1| 58. 6| 12| 7. 8| 56. 6| 14| 1. 9| 55. 1| 16| 0. 1| 54. 4| 18| 0. 1| 54. 4| Calculations: 1) Line of best fit: y=0. 1981x+54. 752 Slope (m): 0. 198 mm/C Y-Intercept (b): 54. 8 mm 2) Absolute zero (V=0): -276. 8°C 3) % Error:Excepted value: -273°C Discussion: My results show that as the temperature of the water decreased, the distance between the two mercury plugs decreased. This supports Charles’ Law which states . When creating my graph, I did not include the first initial temperature and length recordings. The plot was not anywhere near the others, and would have thrown off the slope. My value for absolute zero was fairly close to the excepted -273°C. There was a small difference of 3. 8°C between the two values, with a percent error or 1. 4%.My results were expected because I was obviously not going to get the perfect -273°C absolute zero value, due to experimental error. Sources of experimental error that could occur are if the initial temperature of the water was over 55°C and if the mercury plugs were not fully submerged in the water. If the water was over 55°C, then the ruler would have deformed from melting. This would make the ruler’s readings unreliable. If the mercury plugs were not fully submerged in the water then they would not get the full effect of temperature change.