Question

On a warm day when the air temperature is 30°C, a metal can is slowly cooled by adding bits of ice to liquid water in it. Condensation first appears when the can reaches 15°C. What is the relative humidity of the air?

(a) 25%
(b) 50%
(c) 75%
(d) 100%

Answer 1

The relative humidity of the air is approximately 90.0%.

Step-by-step explanation:

Relative humidity is the ratio of the actual amount of water vapor in the air to the maximum amount of water vapor that can be present in the air at a given temperature. The higher the relative humidity, the closer the air is to saturation. To calculate the relative humidity, we can use the formula:

Relative Humidity = (Actual Vapor Pressure / Saturated Vapor Pressure) × 100%

In this case, the temperature drops from 25.0°C to 15.0°C, which causes condensation. Since the relative humidity is 90.0% at 25.0°C, we can assume that the air is nearly saturated and the actual vapor pressure is close to the saturated vapor pressure at 25.0°C. Therefore, the relative humidity remains nearly unchanged when the temperature drops to 15.0°C. So, the relative humidity of the air is approximately 90.0%.