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)?

Verified step by step guidance

1. Identify the given values: The vapor pressure of water at 20.0°C is 2.34 * 10^3 Pa, and the relative humidity is 60%.
2. Understand the relationship between relative humidity, vapor pressure, and partial pressure: Relative Humidity = (Partial Pressure of Water Vapor / Vapor Pressure of Water) * 100%.
3. Rearrange the formula to solve for the partial pressure of water vapor: Partial Pressure of Water Vapor = (Relative Humidity / 100%) * Vapor Pressure of Water.
4. Substitute the given values into the rearranged formula: Partial Pressure of Water Vapor = (60 / 100) * 2.34 * 10^3 Pa.
5. Calculate the partial pressure of water vapor using the substituted values to find the pressure due to water vapor alone in the atmosphere.

Key Concepts

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. It is a measure of a substance's tendency to evaporate and is crucial in determining the humidity and boiling point of liquids. At 20.0°C, the vapor pressure of water is 2.34 * 10^3 Pa.

Relative Humidity

Relative humidity is the ratio of the current partial pressure of water vapor in the air to the vapor pressure of water at the same temperature, expressed as a percentage. It indicates how close the air is to being saturated with moisture. A relative humidity of 60% means the air contains 60% of the maximum water vapor it can hold at that temperature.

Partial Pressure

Partial pressure is the pressure that a single component of a mixture of gases would exert if it occupied the entire volume alone at the same temperature. In the context of humidity, it refers to the pressure exerted by water vapor in the air. It can be calculated by multiplying the relative humidity by the vapor pressure of water at the given temperature.