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Chapter 11 Chemistry Homework Answers: Definitions: Pressure is the force per unit area on a surface. A Newton is A barometer is a devise to measure atmospheric pressure. Millimeters of mercury, torr, atmospheres and pascals are all units of pressure. Dalton’s law of partial pressure states that the total pressure of a gas is the sum of the partial pressures of the component gases. Boyles Law states that the volume of a fixed mass of gas varies inversely with pressure at a constant temperature. Absolute zero is the lowest possible T and is 0 degrees K, and -273 degrees C. Charles Law states that the volume of a fixed mass of gas at constant pressure varies directly with temperature K. Gay-Lussac’s Law states that the pressure of a fixed mass of gas at constant volume varies directly with the K temperature. The Combined Gas Law expresses the relationship between pressure, volume and temperature of a fixed amount of gas. Avagadro’s Law states that equal volumes of gases at the same T and P contain equal numbers of molecules. The Standard Molar Volume of a Gas is the volume occupied by one mole of a gas at STP= 22.4 L. The Ideal Gas Law is the mathematical relationship among P, V, T and the number of moles of a gas. The Ideal Gas Constant is 0.082 L atm/mol K. Graham’s Law of Effusion states that the rates of effusion of gases at the same T and P are inversely proportional to the square roots of their molar masses. Practice Problems: 1.a. due to collisions with the sides of the container b. pressure is the force per unit surface area 2.a. atm, pascals and mmHg, b. I atm = 760 mm Hg, c. a pascal is the pressure exerted by the force of one Newton acting on an area of one square meter, d. 1 atm= 1.01 x 1023 Pa 3.a. the total pressure is a mixture of the sum of the partial pressures of the component gases, b. they are independent of each other 4.a. 1 atm/ 760 mm Hg = x atm/ 125 mm Hg. x=0.16 atm, b. 1 atm/ 1.01 x 1023 Pa= 3.2 atm/ x Pa x=3.23 x 1023 Pa c. 760 mm Hg/101.3 KPa= x mm Hg/5.38 KPa x=40.4 mmHg 5. 760 torr- (0.285 torr + 593.525 torr)= 166.19 torr 6. 742.0 torr- 42.2=699.8 torr 7.P1V1=P2V2 8. V1/T1=V2/T2 9.PV/T=k or P1V1/T1=P2V2/T2 10.a. P1V1=P2V2, V2= 100 ml b. P1=1.35 mmHg 11.a. V1/T1=V2/T2 V2= 93.3 ml b. T1= 588K – 273K= 315 C c.V1= 81 ml 12. V1/T1=V2/T2 140/340=50/T2 T2= -152 C 13. P1V1=P2V2 (.428)(240)=(.724)(V2) V2= 141.9 ml 14.the molar ratios and the volume ratios of the gases are the same and are reflected in the coefficients 15.a. they are proportional/ the same b. V=kn, where n= moles 16. 1 mole of any gas occupies 22.4 L at STP, so the mass varies, but the # of molecules is the same 17. a. PV=nRT b. the relationship between pressure, volume, moles temperature 18. a. and b. 1.08x1023 c. 2.16x1023 19. a. 1 mole b. 22.4 L/1 = 5.6 L/x x=0.25 mole c. 0.125 L/x = 22.4 L/1 mole x= 0.006 mole d. 22.4 L/1 = 0.07 L/x x=0.003 mole 20.a. 32g/22.4 L=8 g/x x=5.6 L b. 21.their mass 22. ammonia, because it is a smaller molecule 23.a. square root of mass of N/Square root of the mass of H= 3.74/1= H effuses 3.74 times as fast as N b. square root of mass of Cl/square root of mass of F = 5.94/4.35= Fl effuses 1.36 times faster