Question

Name: Section: Gas Law Practice (IC-6) 1. At what temperature will 5.00 g of Cl, exert a pressure of 900. torrat a volume of 750 ml? 2. What pressure will be exerted by 25 g of CO, at a temperature of 25 "C and a volume of 500 mL? 3. Find the number of grams of CO, that exert a pressure of 785 torrs at a volume of 32.5 L and a temperature of 32°C 4. An elemental gas has a mass of 10.3 g. If the volume is 58.4 L and the pressure is 758 torts at a temperature of 2.5°C, what is the molar mass of the gas? 5 A flask of unknown volume containing a gas at 4.0 atm is attached to a S.OL evacuated flask. The air from the first flask is allowed to expand into the second flask and the observed final pressure is 2.5 atm. What is the volume of the first flask (L.)? 6. A 300 mL sample of helium at 127°C is cooled to 150°K. What is the volume (mL.) if the pressure is kept constant?

Answer 1

To find the temparature of 5.00g of Cl, Given that Pressure of 900torr at a volume of 750mL First find the moles of Cl, mass moles = molarmass molarmass of Cl, = 70.9 g/mol moles = a 70.9 g/mol = 0.0705mole To find the temparature of Cl, Use the ideal gas law: PV = nRT p = pressure V = volume n=n moles of any gas R = gas constant T = temperature p = 900torr Convert pressure torr to atm 1 atm = 760 torr 1 atm 900torr = 900torr X -= 1.184 atm 760 torr n=0.0705mole R = 0.0821 L.am/mol.K T = ? V = 750mL = 0.750L PV =nRT TPV nR 1.184atm x 0.750L 0.0705molex0.0821L. atm/mol.K = 153.42K Hence the temparature of C1, = 153.42K

(2) To find the pressure Given that 25g of CO2 First find the moles of CO, mass moles molarm ass molarmass of CO, = 44.01g/mol 25g moles=2 44.01g/mol = 0.568mole To find the pressure Use the ideal gas law: PV = nRT p = pressure V = volume n=n moles of any gas R = gas constant T = temperature p = ? n=0.568mole R = 0.0821 L.atm/mol.K T = 25+273 = 298K V = 500mL = 0.500L PV = nRT P=nRT V 0.568mol 0.0821L.atm/mol.Kx298K 0.500L = 27.80atm Hence the pressure = 27.80atm

To find the grames of CO, First find the moles of CO, Use theideal gas law : PV = nRT p= pressure V = volume n=n moles of any gas R = gas constant T = temperature p = 785torr Convert pressure torr to atm 1 atm = 760 torr 785torr = 785tort 1 atm 760 torr _=1.03 atm n = ? R = 0.0821 L.atm/mol.K T= 32+273 = 305K V = 32.5L PV = nRT 1 RT 103atm x 32.5L 0.0821L.atm/mol.Kx305K = 1.336m ol To find the grames of CO, mass = moles Xmolarmass molarmass of CO, = 44.01g/mol mass = 1.336mol 44.01g/mol = 58.80g Hence the grames of CO, = 58.80g