The Combined Gas Law: used when both pressure and temperature change.


A combination of Boyle's Law and Charles' Law.

• The Combined Gas Law is expressed by the equation:
  

   

  Portfolio Assignment 212:
  Scoring criteria

   

  1. Work the following Charles' Law practice problems:
     1. A gas has a volume of 495 cm³ at STP. Assuming no pressure change, what volume will the gas occupy if the temperature is doubled?
     2. A sample of hydrogen gas occupies 2.5 dm³ at 20 ^oC. What will be its volume at -10 ^oC?
     3. A gas occupies a volume of 500 cm³ at 120 ^oC. Assume the pressure does not change, to what temperature must the gas be cooled for the volume to drop 10%?
        
  2. Work the following Combined Gas Law practice problems:
     1. Calculate the volume of a gas at STP if 5.05 dm³ of the gas are collected at 27.5 ^oC and 95.0 kPa.
     2. A gas occupied 355 cm³ at a pressure of 99.5 kPa and a temperature of 22 ^oC. The pressure increases 10 kPa and the temperature drops 7 C^o. What is the new volume?
     3. Assume the respiratory rate for a person is 15 breaths per minute and one breath contains 500 cm³ of air at 20 ^oC and 99.5 kPa. What volume of air, in cubic meters, corrected to standard conditions, does an individual breathe in one day?

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