HW 3C
1. What are the four ideas of the kinetic molecular theory?
2. Which two of the ideas in #1 are not technically true?
3. What is the Van der Waal’s equation? What does it correct for?
4. Which gas in each pair would deviate most from ideality and why?
a. N2 vs. CO
b. CH3OH vs. O2
c. Ne vs. Xe
5. Two equal balloons are made; one with Helium and one with Neon. How much faster does
the Helium balloon deflate compared to the Neon?
6. SO2 diffuses 1.5 times as fast as an unknown gas. What is the molar weight of the unknown
gas?
7. If BH3 is put into one end of a tube marked 0 cm and NF3 is put into the other end marked
100 cm, at what distance mark on the tube do they meet?
8. What is the RMS speed of O2 gas at STP?
9. What is the RMS speed of Rn gas at STP?
10. You have four gas samples:
a. 1 L H2 at STP
b. 1 L of Ar at STP
c. 1 L of H2 at 27 oC and 760 mm Hg
d. 1 L of He at 0 oC and 900 mm Hg
i. Which sample has the most atoms or molecules?
ii. Which sample has the least atoms or molecules?
iii. Which sample has the largest mass?
iv. Which sample has the largest KE?
11. Five identical balloons are each filled to the same volume at the same temperature and
pressure but are filled with CO2, O2, He, N2, and CH4.
a. Which has the greatest mass?
b. Compare the KEavg of the molecules in each of the balloons. Explain.
c. Which should deviate most from ideality? Why?
d. All of the balloons decrease in size over time. Which balloon will be the smallest? Why?
12. CO and CO2 are put in separate containers of the same size and the same temperature. The
pressure of CO gas is 2 atm while the pressure of the CO2 gas is 1 atm.
a. Compare the KEavg of the 2 samples. Explain.
b. Which gas has a greater RMS speed? Explain why
c. Which container contains a greater number of molecules. Justify your answer.
13. Two containers each have a volume of 1.0 L at 298 K. Container A has 0.10 moles of N 2 (g)
and container B has 0.10 moles of H2 (g). The average kinetic energy of the N2 (g) molecules
is 6.2 x10-21 J. Assume both gases exhibit ideal behavior.
a. Is the pressure in the container of H2 greater than, less than, or equal to the pressure of the
N2? Justify your answer.
b. What is the average kinetic energy of the H2 (g) molecules. Justify your answer.
c. The molecules of which gas, N2 or H2have the greater average speed? Justify.
d. What change could be made that would decrease the average kinetic energy of the N 2
molecules? Justify.
e. If the volume of the container of H2 was decreased to 0.50 L at 298 K, what effect would
that have on:
i)
The pressure in the container. Justify.
ii)
The average speed of the H2 molecules. Justify.
2. A rigid 5.0 L cylinder contains 24.5 g of N2 and 28.0 g of O2.
a. Calculate the total pressure, in atm, of the gas mixture in the cylinder at 298 K.
b. The temperature of the gas mixture in the cylinder is decreased to 280 K. Calculate:
i) The mole fraction of N2 in the cylinder
ii)
The partial pressure, in atm, of N2 in the cylinder
c. If the cylinder develops a pinhole-sized leak and the gases begin to escape, would the ratio
of moles of N2/moles of O2 in the cylinder increase, decrease, or remain the same. Justify
your answer