Question

Molecular masses of water and air are 18.02 kg/(mol·mol) and 28.97 kg/(mol·mol), respectively. The room temperature is 40°C under total pressure 101.3 kPa. The relative humidity at 40°C is 73.7 kPa. Find the relative humidity in percent.

Hint:

Relative humidity = \( \frac{vapor pressure}{saturated vapor pressure} \times 100 \).

Answer 1

Correct Answer: 52

Relative humidity formula: \[ RH = \frac{P_{v}}{P_{sat}} \times 100 \] Where: \[ P_{v} = 73.7\ \text{kPa}, P_{sat} = 101.3\ \text{kPa} \] Thus: \[ RH = \frac{73.7}{101.3} \times 100 = 72.7% \] Thus, \[ \boxed{72.7} \]