MORE… Mole/Gas Laws Review

 

Vocabulary

gas

pressure

volume

temperature

Kelvin

kinetic energy

partial pressure

mm Hg

atm

Boyle's Law

Charle's Law

Gay-Lussac's Law

Ideal Gas Law

ideal gas constant

diffusion

Graham's Law

 

Important Identities

K = °C + 273     and 1 atm = ______mmHg

Dalton's Law of Partial Pressure: 

Boyle's Law for P-V Changes [___________ Proportion]:

Charle's Law for T-V Changes [_________ Proportion]:

Combined Gas Law:

Ideal Gas Law:

where R =   __________      

 n = _____________

Review Problems

1. Explain whether the two variables in each scenario are directly or inversely related.

(a) What happens to the pressure when gas particles are added or removed at a constant volume and constant temperature?

 

(b) What happens to the pressure when the volume is either increased or decreased at a constant temperature and constant number of gas particles?

 

2. Dalton’s Law of Partial Pressure:  A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 250 mm Hg.  If P= 50 mm Hg, P= 175 mm Hg, what is P?  What is the total pressure in atm?

3. Boyle's Law for Pressure-Volume Changes:

 (a) The pressure on 2.50 L of anesthetic gas is changed from 760 mm Hg to 304 mm Hg.  What will be the new volume if the temperature remains constant?

 

(b) A given mass of air has a volume of 6.0 L at 1 atm.  What volume will it occupy at 190 mm Hg if the temperature does not change?

 

4. Charle's Law for Temperature-Volume Changes:

(a) If a sample of gas occupies 6.8 L at 327 °C, what is the volume at 27 °C if the pressure does not change?

 

(b) Five liters of air at -50 °C are warmed to 100 °C.  What is the new volume if the pressure is constant?

 

5.  Combined Gas Law:  A 5.0 L air sample at a temperature of -50 °C has a pressure of 800 mm Hg.  What will be the new pressure if the temperature is raised to 100 °C and the volume expands to 7.0 L?

 

6.  Ideal Gas Law:  What pressure will be exerted by 0.450 mol of a gas at 25 °C if it is contained in a vessel whose volume is 650 cm3 (1 cm3  = 1mL)?

 

Mastery Problems

7. If 4.50 gm of methane gas (CH4) is introduced into an evacuated 2.00 L container at

35 °C, what is the pressure in the container in atm?

 

8. A 3.50 L gas sample at 20 °C and a pressure of 650 mm Hg is allow to expand to a volume of 8.00 L.  the final pressure of the gas is 425 mm Hg.  What is the final temperature of the gas in degrees Celsius?

 

9. A gas cylinder contains nitrogen gas at 10 atm pressure and a temperature of 20 °C.  The cylinder is left in the sun, and the temperature of the gas increases to 50 °C.  What is the pressure in the cylinder?

 

10. Calculate the number of liters occupied at STP for a & b:

(a) 2.5 mol N2       (b) 0.600 gm H2       

 

11.  2 KClO3  ®  2 KCl  +  3 O2

      How many grams of potassium chloride are produced if 25.0 g of potassium chlorate decompose?

 

 

12.  N2  +  3 H2  ®  2 NH3

      How many grams of hydrogen are necessary to react completely with 50.0 g of nitrogen in the above reaction?

 

 

13.  Calculate the percent of each element present in potassium phosphate from its formula.