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Combined Gas Law. Units first!. Volume in liters, milliliters, or cm 3 Temperature must always be in KELVIN!!! Pressure can be in atmospheres, torr, or mm of Hg, or kilopascals (kPa) 1 atm = 760 torr = 760 mm Hg = 101.3 kPa. STP.
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Units first! • Volume in liters, milliliters, or cm3 • Temperature must always be in KELVIN!!! • Pressure can be in atmospheres, torr, or mm of Hg, or kilopascals (kPa) 1 atm = 760 torr = 760 mm Hg = 101.3 kPa
STP Stands for Standard Temperature and Pressure (see Ref Table A) 273 K 1 atm or 101.3 kPa
P1V1 P2V2 = T1 T2 Initial conditions New conditions
Gas law problems • What volume will a gas occupy if the pressure on 244 ml of gas at 4 atm is increased to 6 atm? P1= 4 atm P2 = 6 atm V1= 244 ml V2 = ? T1= constant (1) T2 = constant (1)
Set up equation and solve for unknown value 4 atm x 244 ml = 6 atm x V2 1 1 4 x 244 = 6 x V2 4 x 244 = V2= 160 ml 6
You try it! 75 ml of gas is at STP. What volume will the gas occupy if the temp is raised to 75 0C and the pressure increased to 945 torr? CAREFUL! You must first convert temperature into Kelvin!