Collection of Gas Over Water


193 mL of O2 was collected over water on a day when the atmospheric pressure was 762 mmHg. The temperature of the water was 23.0 o C. How many grams of oxygen were collected?


  1. Use Dalton's law and the vapor pressure of water at 23.0 o C to correct the pressure to units of atmoshperes.
    PT = Poxygen +Pwater

  2. Convert the corrected pressure to atmospheres.

  3. Use the ideal gas law to find out how many moles of gas were produced:
    PV = nRT

  4. Use the number of moles and the molecular weight of oxygen to find out how many grams of oxygen were collected.

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