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Determining the initial mole and mass fractions of oxygen and nitrogen in a mixture using Dalton's law of partial pressure. Solution in MS Word.

A reaction vessel contained 5 liters of a mixture of N2 and O2 gases at 25oC and 2 atm pressure. The oxygen in the mixture was completely removed by causing it to oxidize with an excess of electrically heated zinc wire contained in the vessel to non-volatile solid ZnO. The pressure of N2 that remained (measured again at 25oC) was 1.5 atm. What were the mole and mass percent of O2 in the starting mixture?

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From the given data we can calculate the partial pressure of oxygen in the starting mixture:

p(O2) = p - p(N2) = 2 atm - 1.5 atm = 0.5 atm

where p = pressure of N2 and O2 mixture.
According to Dalton's law of partial pressures we ...