Meteorology. The vapor pressure is the pressure of the vapor phase of a substance when it is in equilibrium with the solid or liquid phase of the substance. The relative humidity is the partial pressure of water vapor in the air divided by the vapor pressure of water at that same temperature, expressed as a percentage. The air is saturated when the humidity is 100%. (a) The vapor pressure of water at 20.0°C is 2.34 * 10^3 Pa. If the air temperature is 20.0°C and the relative humidity is 60%, what is the partial pressure of water vapor in the atmosphere (that is, the pressure due to water vapor alone)?

Video transcript

Welcome back everybody. We have a sauna that is operating at a temperature of 55°C, with a relative humidity of about 65%. Now, the vapor pressure of water at that temperature is 1.78 times 10 to the fourth pascal's and we are tasked with finding what the partial pressure of the water vapor inside the sauna is. Well, we know that relative humidity is just the ratio of our water vapor partial pressure, which is what we're looking for compared to the vapor pressure of water at that same temperature. So I'm gonna go ahead and multiply by PV on both sides here and these of course are going to cancel out leaving us with that. The partial pressure of water is just PV times h let's just go ahead and plug in those numbers. We have the the partial pressure of the water vapor is equal to 1.78 times 10 to the fourth times our relative humidity of 100.65, Which when you plug into your calculator gives us a final answer of 1.16 times 10 to the fourth past gals corresponding to our answer choice of C. Thank you all so much for watching. Hope this video helped. We will see you all in the next one