What is the partial pressure of water vapor at $30 ^\circ \textrm{C}$ if the humidity is 75%?

VIDEO TRANSCRIPT

This is Giancoli Answers with Mr. Dychko. Relative humidity is the ratio of partial pressure to saturated vapor pressure. So, saturated vapor pressure is the maximum, you know, amount of water that can fit into the air at that specific temperature. And we'll multiply both sides by the saturated vapor pressure and divide by 100. And we get the partial pressure as humidity multiplied by saturate vapor pressure. So, that's 0.7575 over 100 times 4.24 times 10 to the 3 pascals. When you look in the table 13-3 on page 379, you can see what the saturated vapor pressure is for water at 30 degrees Celsius and it's 4.24 times 10 to the 3 pascals. So, 75% of that is 3.2 times 10 to the 3 pascals and this is the partial pressure of water at 30 degrees Celsius with 75% humidity.