Multiple choice

A cylinder contains 0.3 mole $N_{2}$, 0.1 mole $O_{2}$ and 0.1 mole $He$. If the total pressure of gas mixture is 1 atmosphere, the partial pressure of $O_{2}$ in $mm$ of $Hg$ is:

  1. 152

  2. 304

  3. 380

  4. 760
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A Correct answer
Explanation

Total moles = 0.3 + 0.1 + 0.1 = 0.5. Mole fraction of O2 = 0.1 / 0.5 = 0.2. Partial pressure = mole fraction * total pressure = 0.2 * 1 atm = 0.2 atm. 1 atm = 760 mm Hg. Partial pressure = 0.2 * 760 = 152 mm Hg.

AI explanation

Using Dalton's law of partial pressures, the partial pressure of a gas is its mole fraction multiplied by the total pressure. The total number of moles in the cylinder is 0.3 plus 0.1 plus 0.1, which is 0.5 moles, making the mole fraction of oxygen 0.1 divided by 0.5, equal to 0.2. The total pressure is 1 atmosphere, which equals 760 mm of mercury, so the partial pressure of oxygen is 0.2 multiplied by 760, resulting in 152 mm.

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