(same ratio for every gas) So far we’ve seen… constant PV nT V  1/P (Boyle’s law) V  T (Charles’s law) P  T (Gay-Lussac’s law) V  n (Avogadro’s law) = R (same ratio for every gas) R = 0.08206 L∙atm mol∙K ideal gas constant: PV = nRT Ideal Gas Law NO Units of : mL , mmHg , kPa , grams , °C

(Standard Temperature & Pressure) STP (Standard Temperature & Pressure) 273.15 K & 1 atm

Ideal Gas Law Calculations A 5.00 L balloon is at 0.855 atm and 25oC. How many moles of gas are in the balloon? PV = nRT R = 0.08206 (0.855 atm)(5.00 L) = n (0.08206)(298 K) A balloon shrinks when submerged in cold water (0.855)(5.00) (0.08206)(298) = n n = 0.175 mol

Ideal Gas Law Calculations What is the pressure of 0.435 mol He gas in a volume of 8.12 L at 0.oC? PV = nRT R = 0.08206 P (8.12 L) = (0.435mol )(0.08206)(273 K) (0.435)(0.08206)(273) (8.12) P = P = 1.20 atm

Ideal Gas Law Calculations A sample of aluminum chloride gas weighing 0.0500 g at 350.oC and 760. mmHg of pressure occupies a volume of 19.2 mL. Calculate the Molar Mass of the gas. PV = nRT R = 0.08206 (1.00 atm)(0.0192 L) = n (0.08206)(623 K) n = 0.000376 mol __0.0500 g_ 0.000376 mol Molar Mass grams mole M = = AlCl3 = 133 g/mol