John Boyle's Constant Theory

Boyle’s Law states that when temperature (T) is kept constant, pressure (P) and volume (V) have an inversely proportional relationship. Boyle’s constant (B) can be expressed by V=B/Pwhere volume is (in this lab) cm^3 and pressure is in atm.

Charles’ Law states that when pressure is held constant, temperature and volume are directly proportional. Charles’ constant (C ) can be expressed by V=CTwhere volume is in cm^3 and temperature is in Kelvin.

Gay-Lussac’s Law states that when volume is held constant, temperature and pressure are directly proportional. Gay-Lussac’s constant (G) can be defined as P=GTwhere pressure is in atm and temperature is in Kelvin.

All three laws play a role in the ideal gas law, PV= nRT where P stands for
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This makes volume the dependent variable and temperature the independent variable. The system volume was set by placing the piston about halfway through the cylinder to allow room for it to move up and down with the resulting volume change. The temperature was varied from a near-boiling temperature to a near-freezing temperature. The canister was placed into the water of the varied temperatures to change the temperature for the system. Each temperature changed the volume of the system as seen by the movement of the piston. The change in height was recorded and then that was used to calculate the new volume of the system. Following Charles’ Law, the volume increased as the temperature increased. This is shown in figure 2, the graph of volume vs temperature. To compare the experimental values to Charles’ Law, Charles’ constant was found using V = CT. The original volume of the system and room temperature were plugged in to find C, then various temperatures to find predicted …show more content…
In figure 1, it is evident that the experimental values for volume were always just under the predicted, indicating the leak in the system. Each series: room temperature (21°C), a hotter temperature (90°C), and a colder temperature (3°C) follows the trendline of predicted values. Also, as they are all about the same, it shows that temperature does not matter when finding volume after a change in pressure, as long as it is held constant.

The experimental values for Charles’ Law loosely follow the trend line of predicted values, as evident in figure 2. It starts off quite close, but then as the temperature and volume are increasing, the volume falls short of predicted more and more. This is because of a known air leak in the system. After each test, the volume was reset to try to eliminate error from the leak, but clearly that was not enough to counteract the leaks effect. Interestingly, the higher pressure did not mean more air leaked out compared to the lower pressures. It is shown that regardless of pressure, volume and temperature are still directly proportional, which is the premise of Charles’

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