Multiple choice

Two non-reactive gases A and B are present in a container with partial pressures 200 and 180 mm of Hg .When a third non-reactive gas C is added then total pressure becomes 1 atm then mole fraction of C will be :

  1. 0.75

  2. 0.5

  3. 0.25

  4. cannot be calculated
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total pressure = 1 atm = 760 mm Hg. Partial pressures of A and B are 200 and 180. Pressure of C = 760 - (200 + 180) = 760 - 380 = 380 mm Hg. Mole fraction of C = P_C / P_total = 380 / 760 = 0.5.

AI explanation

The total pressure of the gases A and B before adding C is 200 plus 180, which equals 380 mm of Hg. Converting 1 atm to mm of Hg gives a new total pressure of 760 mm of Hg, so the partial pressure of gas C is 760 minus 380, resulting in 380 mm of Hg. According to Dalton's law of partial pressures, the mole fraction of gas C is its partial pressure divided by the total pressure, which is 380 divided by 760, equaling 0.5.

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