Dalton’s law of partial pressures: write the correct relation Let pb be barometric pressure, pa the partial pressure of dry air, and pv the partial pressure of water vapour in a gas mixture at the same location. Choose the correct equation.
Mechanical Engineering
Heat Transfer, Refrigeration and Air Conditioning
Difficulty: Easy
Choose an option
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Ap<sub>b</sub> = p<sub>a</sub> − p<sub>v</sub>
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Bp<sub>b</sub> = p<sub>a</sub> + p<sub>v</sub>
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Cp<sub>b</sub> = p<sub>a</sub> × p<sub>v</sub>
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Dp<sub>b</sub> = p<sub>a</sub> / p<sub>v</sub>
Answer
Correct Answer: p<sub>b</sub> = p<sub>a</sub> + p<sub>v</sub>
Explanation
Concept/ApproachDalton’s law for ideal gas mixtures: the total pressure equals the sum of the partial pressures of the components.
Thereforepb = pa + pv.
Common pitfallSubtracting or multiplying partial pressures has no basis in Dalton’s law.
Final Answerpb = pa + pv