Gases in Chemical Reactions Stoichiometry Revisited

STRATEGIZE You can determine the mass of oxygen from the amount of oxygen in moles, which you can calculate from the ideal gas law if you know the partial pressure of oxygen. Since the oxygen is mixed with water vapor, you find the partial pressure of oxygen in the mixture by subtracting the partial pressure of water at 293 K (20 °C) from the total pressure. 

use the ideal gas law to determine the number of moles of oxygen from its partial pressure, volume, and temperature. 

Finally, use the molar mass of oxygen to convert the number of moles to grams. 

SOLVE Follow the conceptual plan to solve the problem. Begin by calculating the partial pressure of oxygen in the oxygen/ water mixture. You can find the partial pressure of water at 20 °C in Table 5.4. 

Before substituting into the ideal gas law, convert the partial pressure of oxygen from mmHg to atm. 

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