The relative humidity of air equals the ratio of the par- tial 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 58% and its temperature is 68 °F, how many molecules of water are present in a room measuring12ft * 10ft * 8ft?

Relative humidity is a measure of the amount of water vapor present in the air compared to the maximum amount of water vapor the air can hold at a given temperature. It is expressed as a percentage, calculated by dividing the partial pressure of water vapor by the equilibrium vapor pressure of water at that temperature, then multiplying by 100. Understanding relative humidity is crucial for determining the moisture content in the air.

Partial pressure refers to the pressure exerted by a single component of a mixture of gases. In the context of humidity, it specifically relates to the pressure of water vapor in the air. The concept is essential for calculating relative humidity and understanding how gases behave in mixtures, as each gas contributes to the total pressure independently.

The Ideal Gas Law is a fundamental equation in chemistry that relates the pressure, volume, temperature, and number of moles of a gas. It is expressed as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature in Kelvin. This law is vital for calculating the number of molecules of water vapor in a given volume of air, especially when temperature and pressure conditions are known.