1411 -CHAPTER 5- Practice Problems
GASES
1. Perform the following conversions:
a) 0.357 atm to torr b) 6.60x10-2 torr to atm c) 745 torr to pa d) 802 mmHg to atm
2. A barometer reads the atmospheric pressure 764.7 torr. A sample of gas is placed in vessel attached
to an open-end mercury monometer. The level of mercury in the open-end arm of the monometer
has a height of 136.4 mm, and that in the arm that is in contact with the gas has a height 103.8 mm.
What is the pressure of gas in atmosphere?
3. Write an equation or proportionality expression that expresses each of the following statements:
a) Law of combining volumes explained by Avogadro,s hypothesis.
b) For a given quantity of gas, the product of pressure and volume is proportional to absolute
temperature.
c) For a given quantity of gas at constant temperature, the product of pressure and volume is
constant.
4. Calculate the following quantities for an ideal gas:
a) Pressure, in atms, if 8,25x10 - 2 mol occupies 174 ml at -15 0C;
b) Number of moles in 2.50 L at 37 0C and 725 torr.
c) Volume of a gas occupied by 6.72x10 - 3 mole at 145 0C and a pressure of 59.0 torr;
d) Absolute temperature of the gas at which 9.87x10 - 2 mol occupies 164 ml at 682 torr;
5. Consider 5.62 L chlorine gas, Cl2 ,at 740 torr and 33 0C.
a) What volume will the gas occupy at 107 0C and 680 torr?
b) What volume will the gas occupy at STP?
c) At what pressure will the volume be 5.00 L if the temperature is 67 0C?
d) At what pressure will the volume be twice as much as original, if temperature remains constant?
e) How many moles Cl2 gas are in original condition?
6. Calculate the following
a) Density of SO3(g) at 0.96 atm and 35 0C.
b) Density of SO3(g) at STP condition.
c) Molar mass of a gas if its density is 3.67 g/L at 15 0C and 825 torr.
d) Molar mass of gas if 4.40 g occupies 3.50 L at 560 torr and 41 0C.
e) Molar mass of a gas if its density is 2.86 g/L at STP , also identify the molecular formula of the
gas.
7. Perform the following calculations;
a) Partial pressure and total pressure of each of the following gases in the mixture of 4.00 g of each
gas CH4(g), C2H4(g) and C4H10(g), in 1.50 L flask at 0 0C.
b) Partial pressure of each component in a mixture of gases contains 0.55 mol N2, 0.20 mol O2, and
0.10 mol CO2. The total pressure of the mixture is 1.32 atm.
c) Partial pressure of each component in a mixture of gases contains 3.50 g N2, 2.15 g H2, and 5.27 g
of NH3, if the total pressure of the mixture is 2.50 atm.
8. Consider the following gases at 25 0C; CO2, He, Cl2, CO, CH4, N2
a) Place them in order of increasing average molecular speed.
b) Calculate and compare the rms speeds of CO(g) and CO2(g).
c) Calculate the rate of diffusion of gases CH4(g) and He.
d) Which gas effuses 1.41 times faster than O2(g)?
e) Which two gases have the same rate of diffusion?
10. If the atmospheric pressure is 0.975 atm, what is the pressure of the enclosed gas in each of the
cases below?
h
h
h
(I) h = 45 mm
(closed)
(II) h = 78 mm
(open-end)
(III) h = 67 mm
(open-end)