6 Example ProblemA sample of helium gas in a balloon is compressed from 4.0 L to 2.5 L at a constant temperature. If the pressure of the gas in the 4.0 L volume is 210 kPa, what will the pressure be at 2.5 L?P1V1 = P2V2
16 Sample ProblemA gas at 110 kPa and 30.o oC fills a flexible container with an initial volume of 2.oL . If the temperature is raised to 80oC and the pressure increased to 440 kPa, what is the new volume?
17 Avagadro’s PrincipleEqual volumes of gases at the same temperature and pressure contain equal numbers of particlesMolar volume = the volume one mole of gas occupies at 0oC and 1.0 atm pressureOne mole of any gas will occupy 22.4L
18 Practice ProblemCalculate the volume that 2.0 Kg of methane gas (CH4) will occupy at STP
19 Ideal Gas LawIdeal gases have almost no volume and the particles are far enough apart to not exert any type of repulsive or attractive force on another particle.Do not exist in real world, but most gases behave like ideal gases at STPPV=nRT
20 PracticeCalculate the number of moles of gas contained in a 3.0L vessel at 3.00 x 102 K with a pressure of 1.5 atmPV = nRTP = 1.5 atmV = 3.0LR = .0821T = 3oo KN = ?
21 Gas StoichiometryRemember, coefficients represent the number of moles of a reactant or product2 C4H O2 8 CO H2O
22 Calculations involving only volume CH4 + 2 O2 CO2 + 2H2OIt takes 2 liters of oxygen to react with 1 L of methane to produce 1 liter of carbon dioxide and 2 liters of water
23 Volume to volume problem What volume of oxygen gas is needed for the complete combustion of 4.0 L of propane gas (C3H8)? Assume constant pressure and temperature.C3H8 + 5O2 3CO2 + 4H2OStart with what you know: 4.0L C3H8What is the ratio of Oxygen to propane? 5 oxygen1 propane3. Multiply the amount of propane by the ratio to get oxygen 5 x 4 = 20 L
24 Volume to Mass ProblemAmmonia is synthesized from hydrogen and nitrogen gases. N2 + 3H2 2 NH3If 5.00 L of nitrogen reacts completely by this reaction at a constant pressure and temperature of 3.00atm and 298K, how many grams of ammonia are produced?
25 1. Analyze problem (V, P, T, ) 2. Solve for unknown Determine volume ratioUse ratio to determine liters of ammonia producedRearrange and use ideal gas law to solve for n (use liters of ammonia produced as V)3. Convert moles of ammonia to grams of ammonia