# Gas Laws - University of California, Irvine Gas Laws Advanced Problem Solving Please turn off all downloads. You can usually pause them by clicking on them and clicking pause. Facebook and youtube are officially banned during class time (this is not me micromanaging, its a legit internet issue as told to me by OIT). Visit: https://checkin.ics.uci.edu/ Log in and select Chem 1A. When prompted, type the word of the day: tougher Remember back 5 rows of even side are no seating zones Ensure when asked if you will share your location you select allow. Visit: https://learningcatalytics.com/ Sign in MasteringChemistry account name When prompted, type session ID:28491493 Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493 SURVEY QUESTIONS

Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493 How to know what specific formulas to use for specific gas law problems 1 1 2 2 Use PV=nRT if only one set of conditions are given, in which case nothing cancels.= 1 1 2 2 Use ratio form, if two sets of conditions are given. Cancel anything that is constant. Will we has problems that use limiting reagents and ideal gas laws? Will the final contain ideal gas law problesm? Absolutely and yes. The final will contain everything. A myriad of questions about conversions between moles and grams, mol ratios, and using chemical reactions for mol ratios. Please come see me/ Paul/ Tutors in office hours. Do we need to know {insert whatever conversion you are wondering about here}? No, they are on the front page of the exam equation sheet that you already have. DALTONS LAW Dinitrogen oxide gas was generated from the thermal decomposition of ammonium nitrate and collected over water. The

wet gas occupied 126 mL at 21 C when the atmospheric pressure was 755 Torr. What volume would the same amount of dry Dinitrogen oxide have occupied if collected at 755 Torr and 21 C. The vapor pressure of water is 18.65 Torr at 21 C. Pressure of N2O: Atmospheric =P(N2O)+P(H20vapor) Hint 1: If the total pressure is 755 Torr, what is the pressure of N2O? Hint 2: How do you determine thehttps://checkin.ics.uci.edu/ volume of a gas at a new Visit: Word of the day: tougher pressure? 755-18.65 torr=736.35 torr Then use: LearningCatalytics: session ID:28491493 V2=123mL REACTIONS: SINGLE GAS PRODUCT Suppose that 200.0 mL of propane gas C3H8 at 1.00 atm and 298K is mixed with 1.00 L of oxygen gas at the same pressure and temperature and burned to form carbon dioxide gas and liquid water. Determine the final volume of the reaction mixture at 2.00 atm and 298 K if the reaction goes to completion. (note: volume of liquid water is negligible).

Hint1: Write out the equation and balance it. Balance Carbons and Hydrogens first then oxygens. Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493 1C3H8:5O2 mol V mol ratio= volume ratio (At constant temp/pressure) REACTION S: Hint 2: Check for any limiting reagents, which may leave some gaseous reactant unreacted. You could solve for moles of CO2 here, but that would be a lot of calculations and a lot of time/possibilities for mistakes. Instead look

for how much volume would be made at the SAME temp and pressure, and then alter it for the new Short way: more thinking, more logic jumps, less math Suppose that 200.0 mL of propane gas C3H8 at 1.00 atm and 298K is mixed with 1.00 L of oxygen gas at the same pressure and temperature and burned to form carbon dioxide gas and liquid water. Determine the final volume of the reaction mixture at 2.00 atm and 298 K if the reaction goes to completion. (note: volume of liquid water is negligible). 1C3H8 : 5O2 mol V mol ratio= volume ratio (At constant temp/pressure) 200.0mL of propane requires 1.00L of O2 We have exactly that, no excess reagent, reaction goes to You may fill in and solve OR Pressure doubles, so volume. Halves

Volume=300.mL Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493 Long way: less thinking, less logic jumps, more math REACTIONS: SINGLE GAS PRODUCT Suppose that 200.0 mL of propane gas C3H8 at 1.00 atm and 298K is mixed with 1.00 L of oxygen gas at the same pressure and temperature and burned to form carbon dioxide gas and liquid water. Determine the final volume of the reaction mixture at 2.00 atm and 298 K if the reaction goes to completion. (note: volume of liquid water is negligible). 3 8= 2 = = = 1.00 0.2000 =0.008175 3 8 0.0821 298

1.00 1.00 =0.040873 2 0.0821 298 3 2 =0.245 1 3 8 3 2 =0.245 5 3 8 Same mol created. Both are used up! 0.245mol CO2 created! 2 = = 298

=0.300 2 2.00 0.245 0.0821 Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:284 REACTIONS: The reaction of solid dimethylhydrazine, (CH3)2N2H2, and liquefied dinitrogen tetraoxide, has been investigated as a rocket fuel; the reaction produces gaseous carbon dioxide, nitrogen and water vapor, which are ejected as exhaust gases. In a controlled experiment solid H2O dimethylhydrazine reacted with excess nitrogen tetroxide with a final N2 pressure of 2.50 atm, with a temperature of 400.0K. Find the pressure CO2 of each gas. Type the total pressure into learning catalytics. Hint: Write out and balance the equation. Hint2: what do you think must be true of the ratio of the gases pressures? Remember nP They must equal the mole ratios coefficients: 4 H 2O: 2 CO2: 3N2 Hint3: What is the total pressure? What are the mol ratios of products? H2O=(4/9)*(2.50 atm)=1.11atm

CO2=(2/9)*(2.50 atm)=0.556 atm N2=(3/9)*(2.50atm)=0.834 atm Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:2849 A 1.00 L sample of chlorine gas at 1.00 atm and 298 K reacts completely with 1.00 L of nitrogen gas and 2.00 L of oxygen gas at the same temperature and pressure. There is a single gaseous product, which fills a 2.00L flask at 1.00 atm and 298 K. Use this information to determine the following characteristics of the product. A) its empirical formula, B) its molecular formula, C) the most favorable Lewis structure based on formal charge arguments (the central atom is an N atom); d) the molecular shape. Hint 1: (a)reacts completely in this question means no limiting reagent, everything reacts all the way to zero. A) B) Ratio of gas moles=ratio of gas volume: 1Cl2:1N2:2O2 Plan: find total grams, find total moles. Do grams/moles. Hint 2: (a) Remember V n at constant To find total grams: do the following for each reactant:

pressure. Also dont forget the reactants are diatomic gases. Then Turn into g using molar mass Hint 3: (b) You know P, V, T of the final reaction To find final total moles: use ideal gas law for final reaction flask. flask, what is n?, what mass of reactants were put in? Where did all Visit: https://checkin.ics.uci.edu/ those reactants go. Word of the day: tougher What is the units of LearningCatalytics: session ID:28 A 1.00 L sample of chlorine gas at 1.00 atm and 298 K reacts completely with 1.00 L of nitrogen gas and 2.00 L of oxygen gas at the same temperature and pressure. There is a single gaseous product, which fills a 2.00L flask at 1.00 atm and 298 K. Use this information to determine the following characteristics of the product. A) its emperical formula, B) its molecular formula, C) the most favorable Lewis structure based on formal charge arguments (the central atom is an N atom); d) the molecular shape. Find total g Put in by doing each reactant separately:

Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493 1.15g+2.90g+2.62g=6.67g total MORE REACTIONS: (Im not sure well make it to this one, if we dont the answer will be posted online) A 1.00 L sample of chlorine gas at 1.00 atm and 298 K reacts completely with 1.00 L of nitrogen gas and 2.00 L of oxygen gas at the same temperature and pressure. There is a single gaseous product, which fills a 2.00L flask at 1.00 atm and 298 K. Use this information to determine the following characteristics of the product. A) its emperical formula, B) its molecular formula, C) the most favorable Lewis structure based on formal charge arguments (the central atom is an N atom); d) the molecular shape. Ratio of gas moles=ratio of gas volume: 1Cl2:1N2:2O2 Total Mass (from other slide) =6.67g total Visit: https://checkin.ics.uci.edu/ Word of the day: tougher

LearningCatalytics: session ID:284 Total Moles reactant: Compare to mass of NClO2=14+35+32= 81g/ mol= same, so NClO2 is also the molecular A 1.00 L sample of chlorine gas at 1.00 atm and 298 K reacts completely with 1.00 L of nitrogen gas and 2.00 L of oxygen gas at the same temperature and pressure. There is a single gaseous product, which fills a 2.00L flask at 1.00 atm and 298 K. Use this information to determine the following characteristics of the product. A) its emperical formula, B) its molecular formula, C) the most favorable Lewis structure based on formal charge arguments (the central atom is an N atom); d) the molecular shape. Steric number 3: trigonal planar. hy cant we add another double bond to minimize formal charge furth Visit: https://checkin.ics.uci.edu/ Word of the day: tougher LearningCatalytics: session ID:28491493