Multiple choice

A gaseous mixture contain 56 grams of N 2 , 44 grams of C O 2 and 16 grams of C H 4 . The total pressure of the mixture is 720 m m H g . The partial pressure of C H 4 is:

  1. $180$ $mm$
  2. $360$ $mm$
  3. $540$ $mm$
  4. $720$ $mm$
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A Correct answer
Explanation

Calculate the moles of each gas: N2 (56/28 = 2 mol), CO2 (44/44 = 1 mol), and CH4 (16/16 = 1 mol). The total moles are 4. The mole fraction of CH4 is 1/4, so its partial pressure is 1/4 of the total pressure (720 mm Hg), which is 180 mm Hg.

AI explanation

By Dalton's law of partial pressures, the partial pressure of a gas in a mixture is equal to its mole fraction multiplied by the total pressure. The given masses translate to 2 moles of nitrogen, 1 mole of carbon dioxide, and 1 mole of methane, totaling 4 moles. The mole fraction of methane is 1 divided by 4, or 0.25, so its partial pressure is 0.25 multiplied by 720 mm Hg, resulting in 180 mm.

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