Ch 202 Problem 10.66

A mixture of gases contains 10.25 g N₂, 1.83 g H₂, and 7.95 g of NH₃. If the total pressure of the mixture is 1.85 atm, what is the partial pressure of each component?

Here, we apply Dalton's Law of partial pressures, which states that the total pressure of a mixture of gases equals the sum of the pressures that each gas would exert if it were present alone. So in our example, we have to find the partial pressures P_N2, P_H2 and P_NH3. We do this for each gas by the relation

P₁ = X₁P_total

where P₁ is the partial pressure of component 1, X₁ is the mol fraction of component 1, and P_total is the total pressure. Considering that we don't know the temperature and volume, are there any other ways to do this problem?

first, we find moles of the components:

mol N₂

mol H₂

mol NH₃

now we compute mol fractions:

mol fraction nitrogen:

mol fraction hydrogen:

all the mol fractions must sum to 1, so for ammonia,

now, find the partial pressures:

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DAC 7/14/08