Multiple choice

Equal volumes of two gases which do not react together are enclosed in separate vessels. Their pressures are 100 mm and 400 mm respectively. If the two vessels are joined together, then what will be the pressure of the resulting mixture (temperature remaining constant)?

  1. 125 mm

  2. 500 mm

  3. 1000 mm

  4. 250 mm
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D Correct answer
Explanation

Since the vessels have equal volumes and are joined, the total volume doubles. By Boyle's Law (P1V1 + P2V2 = PfVf), where V1=V2=V and Vf=2V: 100*V + 400*V = Pf*(2V). Thus, 500 = 2*Pf, so Pf = 250 mm.

AI explanation

By the law of partial pressures for equal volumes, the total pressure of the mixture is the simple arithmetic mean of the two initial pressures since the temperature is constant. You add the two given pressures together: 100 mm plus 400 mm equals 500 mm. Dividing this sum by two gives a resulting pressure of 250 mm.

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