Rica Abercrombie

Rica Abercrombie

Published: 21 Sep 2023

Source: Pubs.acs.org

Vapor pressure is an essential concept in chemistry that plays a crucial role in understanding the behavior and properties of substances in both gas and liquid phases. It refers to the pressure exerted by the gaseous form of a substance when it is in equilibrium with its liquid or solid phase. Understanding vapor pressure is essential in various fields, including thermodynamics, chemical engineering, and even environmental science.

In this article, we will delve into the fascinating world of vapor pressure and explore 18 unbelievable facts related to this concept. From understanding how intermolecular forces affect vapor pressure to exploring the impact of temperature and boiling point on this phenomenon, we will uncover intriguing insights that highlight the significance of vapor pressure in our everyday lives and scientific endeavors.

Table of Contents

Vapor pressure is the measure of the tendency of a substance to vaporize.

Vapor pressure is the pressure exerted by the gaseous phase of a substance when it is in equilibrium with its liquid or solid phase at a given temperature. It represents the escape of molecules from the surface of a liquid or solid into the gas phase.

Vapor pressure increases with temperature.

As the temperature of a substance increases, the kinetic energy of its molecules also increases. This leads to an increase in the number of molecules that have sufficient energy to overcome the attractive forces holding them in the liquid or solid phase, resulting in a higher vapor pressure.

The vapor pressure of a substance is affected by its intermolecular forces.

The strength of intermolecular forces, such as hydrogen bonding or van der Waals forces, affects the vapor pressure of a substance. The stronger the intermolecular forces, the lower the vapor pressure, as more energy is needed to break these forces and convert the substance into the gas phase.

Vapor pressure determines the boiling point of a liquid.

The boiling point of a liquid is reached when its vapor pressure equals the atmospheric pressure. At this point, the liquid changes into the gas phase throughout the bulk of the substance.

Substances with higher vapor pressures evaporate more quickly.

A substance with a higher vapor pressure allows a greater number of molecules to escape from the liquid or solid into the gas phase, resulting in faster evaporation. This is why volatile substances, such as gasoline or ethanol, evaporate quickly.

Vapor pressure is influenced by the surface area of a liquid.

A larger surface area provides more space for molecules to escape into the gas phase, increasing the vapor pressure. This is why substances like perfume are often stored in wide-mouthed bottles to allow for greater evaporation.

Vapor pressure affects the rate of evaporation.

As vapor pressure increases, the rate of evaporation also increases. This is because there are more molecules with sufficient energy to escape into the gas phase.

Different substances have different vapor pressures at the same temperature.

The vapor pressure of a substance depends on its molecular weight, intermolecular forces, and temperature. Therefore, different substances will have varying vapor pressures even if they are at the same temperature.

Vapor pressure can be used to determine the purity of a substance.

If a liquid is pure, its vapor pressure will be consistent with the known vapor pressure of that substance at a given temperature. Deviations in vapor pressure can indicate the presence of impurities.

Vapor pressure is used to measure volatile organic compounds (VOCs) in the air.

By measuring the vapor pressure of certain organic compounds in the atmosphere, scientists can assess air quality and the presence of potentially harmful pollutants.

Vapor pressure is crucial in the design of pressure cookers.

Pressure cookers work by increasing the vapor pressure inside the cooker, which allows food to cook at higher temperatures and speeds up the cooking process.

Vapor pressure is essential in the operation of distillation and fractional distillation processes.

Distillation involves separating different components of a mixture based on their differing vapor pressures. The substances with higher vapor pressures will evaporate first, allowing for their separation from the mixture.

Vapor pressure is used in the production of beverages and alcoholic drinks.

The control of vapor pressure during the fermentation and distillation processes is crucial for producing alcoholic beverages with desired flavors and alcohol content.

Vapor pressure is a key factor in the safety and handling of volatile chemicals.

Knowledge of the vapor pressure of volatile chemicals is important for handling and storage, as substances with high vapor pressures can pose flammability or toxicity risks.

Vapor pressure can be affected by the presence of solutes in a solution.

When a solute is added to a solvent, it can alter the vapor pressure of the solvent. This phenomenon is utilized in certain industrial processes, such as freeze-drying, where the addition of solutes lowers the vapor pressure, allowing for the removal of water from a substance.

Vapor pressure determines the volatility of a substance.

The volatility of a substance refers to how readily it vaporizes. High vapor pressure is an indication of high volatility, while low vapor pressure indicates low volatility.

Vapor pressure plays a role in climate and the water cycle.

Water vapor, with its specific vapor pressure, is a crucial component of the Earth’s atmosphere and plays a fundamental role in weather patterns, precipitation, and the water cycle.

Understanding vapor pressure is essential in many fields, including chemistry, physics, and engineering.

From designing chemical processes to optimizing the performance of engines, a deep understanding of vapor pressure is vital in various scientific and technological applications.


Vapor pressure is a fascinating concept in chemistry, and understanding it can provide valuable insights into various phenomena. We’ve covered 18 unbelievable facts about vapor pressure, ranging from its definition to its applications in everyday life.

From the surprising fact that vapor pressure increases with temperature to the connection between vapor pressure and boiling point, we’ve explored the intricate relationship between pressure, temperature, and molecular behavior.

Additionally, we’ve discussed how vapor pressure is affected by atmospheric pressure, the role of intermolecular forces in determining vapor pressure, and the impact of volatile substances on the surrounding environment.

By delving into these intriguing facts, we can deepen our understanding of vapor pressure and its significance in chemistry. Whether you’re a chemistry enthusiast or simply curious about the world around you, these facts provide a fascinating glimpse into the wonders of vapor pressure.


Q: What is vapor pressure?

A: Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature.

Q: What factors affect vapor pressure?

A: Temperature, intermolecular forces, and the nature of the substance are the primary factors that influence vapor pressure. Higher temperatures and weaker intermolecular forces result in higher vapor pressures.

Q: How does vapor pressure relate to boiling point?

A: The boiling point of a substance is the temperature at which its vapor pressure equals the atmospheric pressure. Substances with high vapor pressures have lower boiling points.

Q: How does atmospheric pressure impact vapor pressure?

A: An increase in atmospheric pressure leads to an increase in the boiling point of a substance and a decrease in its vapor pressure.

Q: What are some practical applications of vapor pressure?

A: Vapor pressure has numerous applications, such as in the process of distillation, where different substances are separated based on their boiling points and vapor pressures. It also plays a significant role in the functioning of refrigeration systems and in understanding the process of evaporation.

Q: How is vapor pressure measured?

A: Vapor pressure is commonly measured using techniques such as the manometer, the vapor pressure osmometer, and the Knudsen effusion method.