The combined gas law is a gas law which combines Charles's law, Boyle's law,and Gay-Lussac's law. These laws each relate onethermodynamic variable to another mathematically while holding everything else constant. Charles's law states that volume and temperature are directly proportional to each other as long as pressure is held constant. Boyle's law asserts that pressure and volume are inversely proportional to each other at fixed temperature. Finally, Gay-Lussac's law introduces a direct proportionality between temperature and pressure as long as it is at a constant volume. The inter-dependence of these variables is shown in the combined gas law, which clearly states that:
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The ratio between the pressure-volume product and the temperature of a system remains constant.
PV=k T where: p is the pressure V is the volume T is the temperature measured in kelvins k is a constant (with units of energy divided by temperature).
For comparing the same substance under two different sets of conditions, the law can be written as:
Check out this video and answer the problems below.
1) A sample of sulfur dioxide occupies a volume of 652 mL at 40.° C and 720 mm Hg. What volume will the sulfur dioxide occupy at STP?
2) A sample of argon has a volume of 5.0 dm3 and the pressure is 0.92 atm. If the final temperature is 30.° C, the final volume is 5.7 L, and the final pressure is 800. mm Hg, what was the initial temperature of the argon?
3) 322 L of hydrogen occupies a volume of 197 L at STP. What was the initial pressure exerted on the hydrogen?
4) The initial temperature of a 1.00 liter sample of argon is 20.° C. The pressure is decreased from 720mm Hg to 360 mm Hg and the volume increases to 2.14 liters. What was the change in temperature of the argon?