Question

Difficulty: EasyVapour Pressure, Boiling, Evaporation, and Relative Humidity

The saturated vapour pressure of water at the dew point of a mass of air is 12 mmHg12\text{ mmHg}, while the saturated vapour pressure at the actual air temperature is 24 mmHg24\text{ mmHg}. Calculate the relative humidity of the air.

Answer: 50 %

Answer

The relative humidity of the air is 50%.
Relative humidity is the ratio of the saturated vapour pressure at the dew point to the saturated vapour pressure at the actual air temperature, expressed as a percentage: (12 mmHg / 24 mmHg) * 100% = 50%.

Step-by-Step Solution

1
Identify the saturated vapour pressure at the dew point and at the air temperature.
SVP at dew point = 12 mmHg; SVP at air temperature = 24 mmHg.
Relative humidity relies on the ratio of partial vapour pressure (SVP at dew point) to maximum vapour pressure at air temperature.
2
Apply the relative humidity formula.
Relative Humidity = (SVP at dew point / SVP at air temperature) * 100%
This formula defines the percentage saturation of the air.
3
Substitute the values and evaluate.
(12 / 24) * 100% = 50%
Dividing 12 by 24 gives 0.5, which equals 50% when multiplied by 100.

Key Concept

Relative Humidity Calculation
Estimated Time:45s
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