# Problem: The relative humidity of air equals the ratio of the partial pressure of water in the air to the equilibrium vapor pressure of water at the same temperature times 100 %.If the relative humidity of the air is 51 % and its temperature is 68°F or 20°C , how many molecules of water are present in a room measuring 18 x 11 x imes9  ft{ m { m ft}} ? Vapor pressure of water at 20°C is 17.5 torr

###### FREE Expert Solution
• Vapor pressure of water varies depending on the temperature. We will be using the pressure from the vapor pressure and plug it in the ideal gas equation to find the number of moles
• This number of moles can be further converted to number of molecules using Avogadro's number.
• Use the volume of the room and the temperature at 20°C for the ideal gas equation
87% (63 ratings) ###### Problem Details

The relative humidity of air equals the ratio of the partial pressure of water in the air to the equilibrium vapor pressure of water at the same temperature times 100 %.

If the relative humidity of the air is 51 % and its temperature is 68°F or 20°C , how many molecules of water are present in a room measuring 18 x 11 x 9  ft ? Vapor pressure of water at 20°C is 17.5 torr