Ch 5 Gas Law Notes
Pressure Problems:
1. How many millimeters of mercury is equal to 1.50 atmosphere?
1140 mmHg
2. Convert the pressure of 955 mm of Hg to the following units:
a. atmospheres
1.26 atm
b. kilopascals
127 kPa
c. pascals
127000 Pa
3. If a force of 9.0 Newtons is applied to an area of 2.0 m2, what is the pressure?
4.5 Pa
4. An open ended manometer measures the atmospheric pressure to be 102 kPa. The difference in the height of the
mercury is 30 mm Hg. What is the pressure exerted by the gas?
795 mmHg
5. A sample of a gas under a pressure of 822 kPa has a volume of 312 cm3. The pressure is increased to a 948 kPa. What
is the new volume of the gas assuming that the temperature is constant? State the gas law that is applied to this
problem _______________________.
270. cm3; Boyle’s Law
6. The volume of a gas is 204 cm3 when the pressure is 925 kPa. A change in pressure caused the volume to change to
306 cm3. What is the pressure that causes this change in volume? State the gas law ____________________________.
616 kPa; Boyle’s Law
7. A sample of gas has a volume of 152 cm3 when its temperature is 18°C. If the temperature is increased to 32°C, what
will the new volume be assuming that the pressure is constant? Sate the gas law _______________________________.
159 cm3; Charles’s Law
8. A sample of gas has a volume of 125 cm3 when its temperature is 25°C. If the volume changes to 98cm3, what is the
new temperature? State the gas law _________________________.
230K; Charles’s Law
9. A gas has a volume of 31.2 dm3 at a temperature of 28°C and a pressure of 82.6 kPa. How many moles are there in the
gas sample? How many molecules are in the sample? The gas is an ideal gas. State the law ________________________.
1.03 mol; 6.19 x 1023 molecules; ideal gas law
10. What volume will 15.0 g of carbon monoxide (CO) occupy at STP? The gas is an ideal gas. State the law
________________________________.
12.0L; ideal gas law
11. How many dm3 of hydrogen gas is released at 25°C and at pressure of 98.3 kPa when 38.2 g of zinc reacts with
hydrochloric acid? State the law ________________________.
14.7 dm3; ideal gas law
12. Consider two samples of nitrogen gas. Sample 1 contains 1.5 moles of N2 and has a volume of 36.7 L. Sample 2 has a
volume of 16.5 L. Calculate the number of moles of N2 in sample 2. State the law _______________________________.
0.67 mol N2; Avogadro’s Law
13. If 46.2 g of oxygen gas occupies a volume of 100.0 L at a particular temperature and pressure, what volume of 5.00 g
of oxygen gas occupy under the same conditions? State the law ____________________________.
10.8L; ideal gas law
14. Consider a sample of hydrogen gas collected over water where the vapor pressure of water is 24 torr. The volume
occupied by the mixture is 0.500 L with a total pressure of 0.950 atm. Calculate the partial pressure of hydrogen gas and
the number of moles of hydrogen gas present. State the law _____________________________.
PH2 = 0.918 atm; n=0.0750 mol (need to know the temp  25°C)
15. A tank contains a mixture of 3.0 mol of N2 , 2.0 mol of O2, and 1.0 mol of CO2 at 25°C. The total pressure in the tank is
10.0 atm. Calculate the partial pressure (in torr) of each gas in the mixture. State the law ________________________.
Pn2 = 3.80 x 103 torr; PO2 = 2530 torr; PCO2 = 1270 torr
16. Calculate the rates of diffusion of oxygen and hydrogen.
Hydrogen diffuses 4X faster than oxygen
17. Which gas would reach you first, carbon dioxide or hydrogen sulfide?
H2S is faster  smaller molar mass
18. Calculate the rates of diffusion of CH4, methane, and sulfur dioxide.
Methane diffuses 2x faster than SO2
19. What is the mass of a 1.00 dm3 sample of oxygen if the volume was measured at 40.0°C and 99.2 kPa, and if the
density of oxygen at 20.0°C and 101.3 kPa is 1.43 g/dm3.
1.31g (you should use the second part to determine the actual molar mass of your particular sample)
20. A sample of helium gas has a volume of 1.24 dm3 when the temperature is 60.0°C and pressure of 202.0 kPa. If the
density of helium is 0.166 g/dm3 at 20.0°C and 101.3 kPa. What is the mass of the sample?
0.361g