1. Ideal Gas Law

2.  It is called the Ideal Gas Law because it assumes that gases are behaving “ideally” (according to the Kinetic-Molecular Theory)  It relates all four variables to each other

3. PV = nRT New variable… R = 0.0821 atm L mol K

4. Sample Problem: How many moles of gas at 100. o C does it take to fill a 1.00 L flask to a pressure of 1.50 atm? n = ? T = 100 o C 100+273=373 K V = 1.00 L P = 1.50 atm PV = nRT 1.50(1.00)=n(0.0821)(373) 1.50 = n(30.6233) 1.50 = n(30.6233) n = 0.0490 mol n = 0.0490 mol

5. Sample Problem: What is the volume occupied by 9.45 g of C 2 H 2 at STP? V = ? m = 9.45 g C 2 H 2 P = 1.00 atm T = 273 K 9.45 g x = 0.36346 mol molPV=nRT(1)(V)=(0.36346)(0.0821) (273) (273) V = 8.15 L

6. A variation of PV=nRT  The R’s always cancel out  Any other variable that stays constant will cancel out

7. Sample Problem: An air filled balloon has a volume of 225 L at 0.94 atm and 25 o C. Soon after, the pressure changes to 0.99 atm and the temperature changes to 0 o C. What is the new volume of the balloon? V 1 = 225 L P 1 = 0.94 atm T 1 = 25 o C P 2 = 0.99 atm T 2 = 0 o C V 2 = ?

8. (0.94)(225) = 298 (0.99)(V 2 ) 273 (0.99)(V 2 ) 273 211.5 = 1.0916 211.5 = 1.0916 0.99 V 2 1.0916(0.99)V 2 = 211.5 V 2 = 195.71 L = 200L V 2 = 195.71 L = 200L