The partial pressure of water vapor in an atmosphere at 35oC and 740 mm Hg pressure is 37 mm Hg. What is the relative humidity? What is the actual concentration of water vapor, expressed in ppm? The vapor pressure of water at 35oC is 42 mm Hg.
To determine the relative humidity, you need to compare the actual concentration of water vapor (partial pressure of water vapor) to the maximum possible concentration of water vapor (vapor pressure of water at the same temperature).
First, let's find the relative humidity:
Relative Humidity = (Partial Pressure of Water Vapor / Vapor Pressure of Water) * 100
Given:
Partial Pressure of Water Vapor = 37 mm Hg
Vapor Pressure of Water at 35°C = 42 mm Hg
Plugging in the values:
Relative Humidity = (37 mm Hg / 42 mm Hg) * 100
Relative Humidity ≈ 88.1%
Therefore, the relative humidity is approximately 88.1%.
Now, let's calculate the actual concentration of water vapor in parts per million (ppm).
To convert from partial pressure to concentration in ppm, we can use the following formula:
Concentration (ppm) = (Partial Pressure / Total Pressure) * 1,000,000
Given:
Partial Pressure of Water Vapor = 37 mm Hg
Total Pressure = 740 mm Hg
Plugging in the values:
Concentration (ppm) = (37 mm Hg / 740 mm Hg) * 1,000,000
Concentration (ppm) ≈ 49,759 ppm
Therefore, the actual concentration of water vapor is approximately 49,759 ppm.