Arkansas
State University
Department
of Chemistry
and
Physics |

Answers |
Gas Laws 2 |

**1. A sample of 0.50 moles of gas is placed in a container of volume
of 2.5 L. What is the pressure of the gas in torr if the gas is at
25 ^{o}C? P = 4.89 atm = 3719 torr**

**2. A sample of gas is placed in a container at 25 ^{o}C and
2 atm of pressure. If the temperature is raised to 50^{o}C,
what is the new pressure? P = 2.17 atm**

**3. At 1 atm of pressure water boils at 100 ^{o}C, if the sample
was placed under 2 atm of pressure, what would be the temperature?
(This would be like a pressure cooker).**

**4. At what temperature would water boil if the pressure is 600 torr?
(Use information from problem 3: this shows why food doesn't cook
well at higher elevations)**
**T = 294 K = 21.5 ^{o}C = 70.7^{o}F**

**5. Calculate the volume of 40.6 g of F _{2} at STP. V
= 23.9 L**

**6. A sample of 2.0 moles of hydrogen gas is placed in a container
with a volume of 10.4 L. What is the pressure of the gas in torr
if the gas is at 25 ^{o}C? P = 4.70 atm =
3576**

**7. The tire pressure is 32 psi. What is the pressure in torr
if 1 atm = 14.7 psi?**
**P = 1654 torr**

**8. A gas is placed in a balloon with a volume of 3.0 L at 28 ^{o}C
and 900 torr. What would be the new volume for the gas if placed
under STP? V = 3.2 L**

**9. How many moles of gas would occupy a volume of 14 L at a
pressure of 700 torr and a temperature of 30 ^{o}C? n
= 0.52 mol**

**10. Calculate the volume of 24.0 g of HCl at STP. V
= 14.8 L**

**11. What is the volume of one mole of acetylene gas at STP? V
=22.414 L**

**12. What is the volume of 0.75 mol of gas at 72 ^{o}C and
2 atm? V = 10.6 L**

**13. After eating beans, a student collects a sample of gas at 0.97
atm and 26 ^{o}C which occupies a volume of 3.5 L, calculate its
volume at STP. V = 3.1 L**

**14. Ammonia (NH _{3}) is placed in 1.5 L flask at 25^{o}C.
If the pressure of the gas is 0.899 atm, what is the density? d
= 0.626 g/L**

**15. A mixture of Ar and CO gases is collected over water at 28 ^{o}C
and an atmospheric pressure of 1.05 atm. If the partial pressure
of Ar is 600 torr, what is the partial pressure of CO? (vapor pressure
of water at 28^{o}C is 28.3 mmHg) P_{CO}
= 0.223 atm**

**16. Determine the partial pressures of each of the gases in the following
mixture: 17.04 g NH _{3}, 40.36 g Ne and 19.00 g F_{2}.
The gases are at 1.5 atm of pressure.**

**17. Potassium chlorate decomposes under heat as follows:**

** 2 KClO _{3} (s) -------> 2 KCl (s)
+ 3 O_{2} (g)**

** The oxygen gas is collected over water at 25 ^{o}C.
The volume of gas is 560 mL measured at 1 atm. Calculate the number
of grams of KClO_{3} used in the reaction. (vapor pressure
of water = 0.0313 atm) n_{O2} = 0.022 mol;
1.81 g KClO_{3}**