Vapor pressure: Difference between revisions

Latest revision as of 04:36, 29 March 2025

Pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases

Vapor pressure (or vapour pressure) is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. It is an indication of a liquid's evaporation rate. The vapor pressure of a substance is a critical property in determining its volatility.

Definition[edit]

Vapor pressure is defined as the pressure exerted by a vapor in equilibrium with its liquid or solid phase. It is a measure of the tendency of particles to escape from the liquid or solid phase into the gaseous phase. The vapor pressure of a liquid varies with its temperature, increasing as the temperature rises.

Factors affecting vapor pressure[edit]

Several factors influence vapor pressure:

Temperature: As temperature increases, the kinetic energy of the molecules increases, leading to a higher vapor pressure.
Nature of the liquid: Different liquids have different vapor pressures at the same temperature due to variations in intermolecular forces.
Presence of solutes: The addition of a non-volatile solute to a liquid decreases its vapor pressure, a phenomenon known as Raoult's law.

Measurement[edit]

Vapor pressure can be measured using various methods, including the manometer method, the dynamic method, and the static method. Each method has its own advantages and limitations, depending on the substance being measured and the conditions of the experiment.

Applications[edit]

Vapor pressure is a crucial concept in many fields:

In meteorology, it is used to describe the humidity of the air.
In chemistry, it is important for understanding distillation and evaporation processes.
In engineering, it is used in the design of equipment such as pressure vessels and heat exchangers.

Related pages[edit]

@@ Line 1: / Line 1: @@
-'''Vapor Pressure''' is a term used in [[thermodynamics]] to describe the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid).
+{{Short description|Pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases}}
+'''Vapor pressure''' (or '''vapour pressure''') is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. It is an indication of a liquid's evaporation rate. The vapor pressure of a substance is a critical property in determining its volatility.
+[[File:Vapor_pressure.svg|thumb|right|Diagram showing the relationship between vapor pressure and temperature.]]
+[[File:Vapor_pressure_being_used_in_a_cloud_chamber.jpg|thumb|right|Vapor pressure in a cloud chamber.]]
+[[File:Water_vapor_pressure_graph.jpg|thumb|right|Graph of water vapor pressure.]]
-== Definition ==
+==Definition==
-Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid). A substance with a high vapor pressure at normal temperatures is often referred to as [[volatile]].
+Vapor pressure is defined as the pressure exerted by a vapor in equilibrium with its liquid or solid phase. It is a measure of the tendency of particles to escape from the liquid or solid phase into the gaseous phase. The vapor pressure of a liquid varies with its temperature, increasing as the temperature rises.
-== Measurement ==
+==Factors affecting vapor pressure==
-Vapor pressure can be measured in the lab by various methods such as the [[isoteniscope]] method and the gas saturation method. It can also be calculated using various theoretical methods such as the [[Clausius–Clapeyron relation]].
+Several factors influence vapor pressure:
-== Factors affecting Vapor Pressure ==
+* '''Temperature''': As temperature increases, the kinetic energy of the molecules increases, leading to a higher vapor pressure.
-Vapor pressure is affected by various factors such as temperature, the nature of the liquid, and the presence of other substances in the liquid.
+* '''Nature of the liquid''': Different liquids have different vapor pressures at the same temperature due to variations in intermolecular forces.
+* '''Presence of solutes''': The addition of a non-volatile solute to a liquid decreases its vapor pressure, a phenomenon known as [[Raoult's law]].
-=== Temperature ===
+==Measurement==
-The vapor pressure of a liquid increases with temperature, as the kinetic energy of the molecules increases. This is described by the [[Clausius–Clapeyron relation]].
+Vapor pressure can be measured using various methods, including the [[manometer]] method, the [[dynamic method]], and the [[static method]]. Each method has its own advantages and limitations, depending on the substance being measured and the conditions of the experiment.
-=== Nature of the Liquid ===
+==Applications==
-The nature of the liquid also affects its vapor pressure. Liquids with higher intermolecular forces tend to have lower vapor pressures.
+Vapor pressure is a crucial concept in many fields:
-=== Presence of other substances ===
+* In [[meteorology]], it is used to describe the humidity of the air.
-The presence of other substances in the liquid can also affect the vapor pressure. For example, the addition of a non-volatile solute to a liquid lowers the vapor pressure of the liquid.
+* In [[chemistry]], it is important for understanding [[distillation]] and [[evaporation]] processes.
+* In [[engineering]], it is used in the design of equipment such as [[pressure vessels]] and [[heat exchangers]].
-== Applications ==
+==Related pages==
-Vapor pressure has many practical applications. It is used in the formulation of [[nail polish]], in the design of [[fuel pump]]s and in the operation of [[steam engine]]s. It is also used in the prediction of [[boiling point]] and in the understanding of [[colligative properties]].
-== See also ==
 * [[Boiling point]]
-* [[Clausius–Clapeyron relation]]
+* [[Partial pressure]]
-* [[Colligative properties]]
+* [[Saturation vapor pressure]]
-* [[Volatile substance]]
 [[Category:Thermodynamics]]
-[[Category:Physical quantities]]
+[[Category:Physical chemistry]]
-[[Category:Gases]]
-{{stub}}