Note the different value and unit for R, to be in agreement with using mmHg for the pressure unit. (0.400 mol) (0.08206 L atm / mol K) (284 K)Įxample #4: Calculate the approximate temperature of a 0.300 mol sample of gas at 780. Note the conversion from mmHg to atm and from Celsius to Kelvin.Įxample #2: A sample of gas at 28.0 ☌ has a volume of 6.20 L and exerts a pressure of 720.0 mmHg. The ChemTeam will use the 0.08206 value in gas-related problems almost every time.Įxample #1: A sample of gas at 25.0 ☌ has a volume of 11.0 L and exerts a pressure of 660.0 mmHg. Those of you that take more chemistry than high school level will meet up with 8.31447 Joules per mole Kelvin, but that's for another time. (Here's a whole bunch.) It depends on which units you select. This is not the only value of R that can exist. Notice the weird unit on R: say out loud "liter atmospheres per mole Kelvin." Solving for R gives 0.08206 L atm / mol K, when rounded to four significant figures. Notice how atmospheres were used as well as the exact value for standard temperature. Let's plug our numbers into the equation: It is the volume of ANY ideal gas at standard temperature and pressure. We will use the value of 22.414 L.īy the way, 22.414 L at STP has a name. The volume of this amount of gas under the conditions of STP is known to a high degree of precision. We will assume we have 1.000 mol of a gas at STP.
If you wind up taking enough chemistry, you will see it showing up over and over and over. Sometimes it is referred to as the universal gas constant. Let the cube root of k 1k 2k 3k 4k 5 / k 6 be called R.Įach unit occurs three times and the cube root yields L-atm / mol-K, the correct units for R when used in a gas law context.
When you multiply them all together, you get: The subscripts on k indicate that six different values would be obtained. Note that the last law is written in reciprocal form. For a static sample of gas, we can write each of the six gas laws as follows: What follows is just one way to "derive" the Ideal Gas Law. The Ideal Gas Law was first written in 1834 by Emil Clapeyron. Fifteen Examples Boyle's Law No Name Law Ideal Gas Law Probs 1-10 Charles' Law Combined Gas Law Ideal Gas Law Probs 11-25 Gay-Lussac's Law Dalton's Law All Ideal Gas Law examples and problems Avogadro's Law Graham's Law Return to KMT & Gas Laws Menu Diver's Law