# What is the Vapor Pressure of Water?

##### Joseph Hebert
Owner at - HVAC Buster

Joseph is an HVAC technician and a hobbyist blogger. He’s been working as an HVAC technician for almost 13 years, and he started blogging just...Read more

Vapor pressure is the pressure of a gas in equilibrium with its non-gaseous form. For example, water has a vapor pressure of 1 atmosphere at 100°C. This means that, if we have an enclosed container of 100°C water, the partial pressure of water vapor in the air will be 1 atmosphere.

The vapor pressure decreases as the temperature decreases. At 0°C, the vapor pressure is only about 0.003 atmospheres.

Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. The vapor pressure of water is the pressure at which water vapor is in equilibrium with its liquid phase. The normal boiling point of water is the temperature at which the vapor pressure of water is equal to atmospheric pressure.

The vapor pressure of water is dependent on temperature. At lower temperatures, the vapor pressure of water is lower than at higher temperatures. This relationship between temperature and vapor pressure is known as the Clausius-Clapeyron equation.

The Clausius-Clapeyron equation states that the Vapor Pressure Of Water (P) Is Related To Temperature (T) By This Equation: P = A exp (-B/(T+C)) where A, B, and C are constants.

This equation shows that the vapor pressure of water increases exponentially with increasing temperature. At 20 degrees Celsius, the vaporpressure OfWateris about 0.0313 atmospheres. This means that if you have a containerofwaterat 20 degrees Celsius, only 3% OfTheWaterwill be in themolecular formOfWater vapour;the rest will beliquidwater molecules .

However, if you increase thetemperatureto 100 degrees Celsius, 97% OfTheWater will be intheformOfWater vapour!

## Vapor Pressure of Water at 25 C

Water vapor is the gaseous state of water and is invisible. Unlike other forms of matter, water vapor does not have a fixed shape or volume. When water vapor condenses, it becomes liquid water.

The pressure that causes this transformation is called the saturated vapor pressure (SVP). The SVP of water varies with temperature. For example, at 25°C, the SVP of water is 23.8 kPa.

This means that if the atmospheric pressure is less than 23.8 kPa, liquid water will evaporate into water vapor until the partial pressure of water vapor in the air reaches 23.8 kPa. The rate at which liquid water evaporates also depends on humidity. If the air is already saturated with moisture (100% relative humidity), then evaporation will occur more slowly because there is nowhere for the additional moisture to go.

In contrast, if the air is dry (0% relative humidity), then evaporation will occur more quickly because there is more space for the moisture to spread out into. The atmosphere typically contains a mixture of different gases, but we usually talk about partial pressures rather than concentrations when discussing individual gases like water vapor. The partial pressure of a gas is proportional to its concentration in a mixture but also depends on the total pressure of all gases in the mixture – so two identical mixtures could have different partial pressures depending on their overall composition

A gas’ Partial Pressure (PP) = Concentration x Total Pressure For example: If we take a sample container of nitrogen gas and add some oxygen to it such that both gases now occupy equal volumes within our sample container; each gas still has what we call 100% concentration but they do not have equal Partial Pressures because they do not contribute equally tothe Total Pressure within our sample container!

## What is the Vapor Pressure of Water at 23 Degrees Celsius

When water is heated, its molecules move faster and collide more frequently. As they collide, they transfer energy to their surroundings. At a certain temperature, called the boiling point, the water begins to vaporize into steam.

The Vapor Pressure of Water at 23 Degrees Celsius is the pressure at which water vapor is in equilibrium with its non-vapor phases. The Vapor Pressure of Water decreases as temperature increases. For example, at 70°C, the Vapor Pressure of Water is about 22mmHg .

## Water Vapour Pressure Calculator

If you are looking for a water vapour pressure calculator, there are many options available online. However, it is important to choose one that is accurate and appropriate for your needs. One option is the “Water Vapour Pressure Calculator” available on the website of the US National Weather Service.

This calculator requires you to input the temperature and dew point, and then provides an output of the water vapour pressure in millibars. Another option is the “Water Vapour Pressure Calculator” available on the website of WeatherInfo UK. This calculator also requires you to input the temperature and dew point, but provides an output in both millibars and inches of mercury.

Finally, the “Water Vapour Pressure Calculator” available on the website of The Engineering ToolBox allows you to input either the temperature or dew point, and provides an output in both millibars and pounds per square inch. Whichever calculator you choose, it is important to double-check the inputs and outputs to ensure accuracy.

## Vapour Pressure of Water at 100°C

Vapour pressure is the equilibrium pressure from a liquid or solid at a given temperature where the molecules are escaping from the surface of the liquid into the vapour phase. The higher the temperature, the greater the vapour pressure. For water, this means that at 100°C, its vapour pressure is much higher than at room temperature (25°C).

The reason for this is that when water molecules are heated to high temperatures, they have more kinetic energy and thus are able to escape from the surface of the liquid more easily. This results in an increase in vapour pressure. In fact, at 100°C, water’s vapour pressure is nearly double what it is at room temperature!

This increase in vapour pressure can be used to advantage in some applications. For example, steam sterilization of medical instruments requires very high temperatures to kill bacteria – and using boiling water (100°C) as a sterilizing agent results in quicker and more effective sterilization than lower temperatures could achieve.

## Definition of Vapour Pressure

Vapour pressure is the pressure exerted by a vapour in equilibrium with its non-vapour phases. The vapour pressure of a liquid is usually lower than the surrounding atmospheric pressure, and increases as the temperature of the liquid increases. The higher the vapour pressure of a liquid, the easier it is for the liquid to vaporize.

## What is the Normal Vapor Pressure of Water?

The normal vapor pressure of water is the equilibrium pressure from a water surface to the atmosphere. The value varies with temperature, but it is typically around 10 kPa (1 atm or 760 mmHg) at room temperature. The vapor pressure increases with increasing temperature and it is often approximately doubled for each 10 °C increase in temperature.

## What is Vapor Pressure of Water at 25 C?

The vapor pressure of water at 25 C is 23.56 kPa. This means that the air pressure above a column of water at this temperature is 23.56 kPa higher than the atmospheric pressure. The vapor pressure of water increases with temperature, so at higher temperatures the vapor pressure will be even higher.

## What is the Vapor Pressure of Water at 22 C?

The vapor pressure of water at 22 C is 17.54 kPa. This means that, at this temperature, the partial pressure of water vapor in the air is equal to 17.54 kPa. The vapor pressure of water varies with temperature – at higher temperatures, the vapor pressure is higher.

## How Do You Find Vapor Pressure of Water?

To find the vapor pressure of water, you need to know the boiling point of water and the atmospheric pressure. The boiling point of water is 100 degrees Celsius or 212 degrees Fahrenheit. The atmospheric pressure is 1 atmosphere.

To find the vapor pressure of water, you divide the boiling point of water by the atmospheric pressure. This gives you a ratio of 100:1. To find the actual vapor pressure, you multiply this ratio by the atmospheric pressure.

This gives you a vapor pressure of 100 atmospheres or 14.7 psi.

## Conclusion

Vapor pressure is the pressure of a gas in equilibrium with its non-gaseous form. The vapor pressure of water is the pressure at which water vapor is in equilibrium with liquid water. It varies with temperature and is usually expressed in millibars (mb) or inches of mercury (inHg).

At sea level and 20°C, the vapor pressure of water is about 17 mb.

Joseph is an HVAC technician and a hobbyist blogger. He’s been working as an HVAC technician for almost 13 years, and he started blogging just a couple of years ago. Joseph loves to talk about HVAC devices, their uses, maintenance, installation, fixing, and different problems people face with their HVAC devices. He created Hvacbuster to share his knowledge and decade of experiences with people who don’t have any prior knowledge about these devices.