Ideal Gas Law Van der Waals combined Boyle’s and Charles’ Laws

PV = nRT P = ? –Pressure (atm) V = ? –Volume (Liters) n = ? –Moles R = ? –Gas Constant ( L atm/ mol K) T = ? –Temperature (Kelvin)

Let’s talk about R Value of R – The UNITS of R –L atm / mol K Do NOT plug anything into the UNITS

Units for R PV = nRT (atm) (L) = (moles) (L*atm) (K) mole K (atm) (L) = (L * atm) (atm) (L)

Let’s try a problem! How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C? P = 1.2 atm V = 2.5 L n = ? T = 25°C ARE THE UNITS CORRECT?

Let’s try a problem! How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C? P = 1.2 atm V = 2.5 L n = ? T = 25°C atm ? L ? Moles ? Kelvin ? How do we convert into Kelvin?

Let’s try a problem! How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C? P = 1.2 atm V = 2.5 L n = ? T = 25°C = 298 K Now we can solve for n

Let’s try a problem! How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C? P = 1.2 atm V = 2.5 L n = ? T = 298 K PV = nRT RT PV = n RT

Let’s try a problem! How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C? P = 1.2 atm V = 2.5 L n = ? T = 298 K PV = n RT (1.2) (2.5) = n (0.0821) (298) moles

Rules for the Test Must show ALL WORK 3 points for correct equation 2 points for correct numbers used in variables (including correct units) 5 points for correct answer (must include UNITS) #4 The temperature is 298K

As Pressure increases, Volume ________ As Temperature increases, Volume _______ What volume will be occupied by 80 grams of CO 2 at a temperature of 20 o C and a pressure of kPa? Helium occupies a volume of 3.8 Liters at - 45 o C, what volume will it occupy at 45 o C? A gas exerts a pressure of 900 Torr. If the pressure is changed to 1.50 atm, and the final volume is 250mL, what is the original volume?