**The following problems are taken from T. L. Brown, H.
E. Lemay, B. E. Bursten, & J. R. Burdge, Chemistry: The Central Science,
Ninth ^{} Edition, Chapter 10. To see the solution to a problem or to
return from the solution, click on the number of the problem.**

20**)** **A sample
of gas occupies a volume of 1248 ft ^{3} at 0.988 atm and 28.0°C.**

** (a) Calculate the pressure
of the gas if its volume is decreased to 978 ft ^{3} while its temperature
is held constant. **

** (b) At what temperature in
degrees Celsius is the volume of the gas 1435 ft ^{3} if the pressure
is kept constant? **

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26**)** ** Suppose
you are given two flasks at the same temperature, one of volume 2 L and the
other of volume 3 L. In the 2-L flask the gas pressure is X atm, and the mass
of gas in the flask is 4.8 g. In the 3-L flask the gas pressure is 0.1X, and
the mass of gas is 0.36 g. Do the two gases have the same molar mass? If not,
which contains the gas of higher molar mass?**

** **

32**)** ** An
aerosol spray can with a volume of 456 mL contains 3.18 g of propane gas (C _{3}H_{8})
as a propellant.**

** (a) If the can is at 23°C,
what is the pressure in the can?**

** (b) What volume would the propane
occupy at STP?**

** (c) The can says that exposure
to temperatures above 130°F may cause the can to burst. What is the pressure
in the can at this temperature?**

** **

46**)** ** Calcium
hydride, CaH _{2}, reacts with water to form hydrogen gas:**

** CaH _{2}(s) + 2H_{2}O(l)
Ca(OH)_{2}_{}(aq) + 2H_{2}(g) **

** This reaction is sometimes used to
inflate life rafts, weather balloons, and the like, where a simple, compact
means of generating H _{2} is desired. How many grams of CaH_{2}
are needed to generate 64.5 L of H_{2} gas if the pressure of H_{2}
is 814 torr at 32°C?**

** **

60**)** ** A sample
of 5.25 g of SO _{2}(g) originally in a 4.00-L vessel at 26°C is
transferred to a 13.6-L vessel at 25°C. A sample of 2.35 g N_{2}(g)
originally in a 3.18-L vessel at 20°C is transferred to this same 13.6-L
vessel.**

** (a) What is the partial pressure
of SO _{2}(g) in the larger container?**

** (b) What is the partial pressure
of N _{2}(g) in this vessel?**

** (c) What is the total pressure
in the vessel?**

** **

66**)** ** Suppose
you have two 1-L flasks, one containing N _{2} at STP, the other containing
CH_{4} at STP. How do these systems compare with respect to:**

** (a) number of molecules**

** (b) density**

** (c) average kinetic energy of the
molecules**

** (d) rate of effusion through a
pinhole leak?**

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