Question

At a temperature of 10oC the percent relative humidity is R10 , and at 40oC it is R40. At each of these temperatures the partial pressure of water vapor in the air is the same. Using the vapor pressure curve for water that accompanies this problem, determine the ratio R10 / R40 of the two humidity values. (Cutnell 357)

Answer 1

Answer:

$\frac{R_{10} }{R_{40} } = 5$

Explanation:

Using the Vapor pressure of water versus temperature curve:

At Relative humidity, $R_{10}$, with equivalent temperature of 10⁰C, the partial vapor pressure, $p_{vs} = 1300 Pa$

At Relative humidity, $R_{40}$ with equivalent temperature of 40⁰C, the partial vapor pressure, $p_{vs} = 6500 Pa$

$\frac{R_{10} }{R_{40} } = \frac{p_{vs} at 10^{0} C}{p_{vs} at 40^{0} C} \\\frac{R_{10} }{R_{40} } = 6500/1300\\\frac{R_{10} }{R_{40} } = 5$