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Grade 11Physical Chemistry

The total pressure of a mixture of oxygen and hydrogen is 1atm . The mixture is ignited and water is removed. The remaining gas is purely hydrogen and exerts a pressure of 0.40 arm then measur d at the same values of T and V as the original volume. What was the original mixture in mole fraction

Profile image of Trisanu Bhar
8 Years agoGrade 11
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1 Answer

Profile image of User
7 Years ago
Since the reaction of H2 and O2 is 2 H2 + O2 --> 2 H2O, then twice as many moles of H2 than O2 were consumed. Or, the consumed air was 2/3 H2 and 1/3 O2. So, since (1.00 - .400) = .6 atm was consumed, that means that, of that 0.6 atm, .4 atm was H2 and .2 atm was O2. So, the initial partial pressures were 0.8 atm H2 and 0.2 atm O2. Since the total is 1.00, those values are also the mole fractions: 
.8 H2 and .2 O2. Converting that to percent: 80 % H2 and 20% O2.