The document discusses several gas laws: Boyle's law states that gas volume is inversely proportional to pressure; Charles's law says gas volume directly increases with temperature; and Gay-Lussac's law finds pressure directly increases with temperature. It provides examples of applying these laws to calculate gas properties when conditions change. The document also introduces Dalton's law of partial pressures, stating the total gas pressure equals the sum of individual gas pressures. Finally, it shows combining multiple gas laws to solve a quantitative problem involving a chemical reaction and collecting the product gas.

1. Gas Laws and Chemistry
• Some Background
• Standard Temperature and Pressure (STP)
• Molar Volume of Gas @ STP
• 22.4 liters

2. What is STP?
• Standard Temperature oK= oC + 273
• Measured in Kelvin 20oC= 293oK
not Celsius
• Standard Pressure
• 760 mm
Lord Kelvin

3. Boyle’s Law
• Volume varies inversely with pressure
Robert Boyle

4. An Application of Boyle’s Law
• What would be the
volume of 15 liters of
gas if the pressure
changed from 700 mm
to 850 mm?
15 liters x 700 mm = 12.35 liters
850 mm

5. Charles’s Law
• Volume varies directly
with temperature
Jacques Charles

6. An Application of Charles’s
Law...
• What would be the volume of 20 liters of
gas at 25oC if the temperature were
changed to 0oC?
Convert oC to oK
25oC (25oC + 273 = 298oK)
0oC (0oC + 273 = 273oK)
20 liters x 273oK = 18.32 liters
298oK
A balloon on dry ice

7. Gay-Lussac’s Law
• Pressure varies directly
with temperature
Joseph Gay-Lussac

8. Application of Gay-Lussac’s
Law
• What would be the change in pressure of a
fixed volume of gas at 40oC and 600 mm
pressure, if the temperature were increased
to 80oC ?
600 mm x 353oK = 676.67 mm
313oK

9. Combined Gas Law Problem
• What would be the volume of 75 liters of a
gas at 30oC and 700 mm pressure if the
temperature and pressure were changed to
70oC and 800 mm?
75 liters x 343oK x 700 mm = 74.29 liters
303oK 800 mm

10. Dalton’s Law of Partial
Pressures
• The total pressure of a
mixture of gases is equal to
the sum of the partial
pressures of the gases

11. Combining the Gas Laws to
Solve a Quantitative Problem
Mg + 2 HCl MgCl2 + H2
• If 0.5 grams of Mg are completely reacted with
HCl to form H2, how many liters of H2 will be
collected over water at 30oC and a pressure of
700 mm?
0.5 g Mg x 1 mole Mg x 1 mole H2 x 22.4 liters H2 = 0.46 liters H2 @ STP
24.31 g Mg 1 mole Mg 1 mole H2

12. The Final Step...
• Take volume of H at STP and convert it to
2
lab conditions using Boyle’s, Charles’s, and
Dalton’s Laws
Dalton’s Law correction
700 mm (pressure at lab conditions) – 31.8 mm (water vapor pressure) = 668.2 mm
0.46 liters H2 x 760 mm x 303oK = 0.58 liters of H2 at lab conditions
668.2 mm 273oK