# What is the Enthalpy of Vaporization?

##### 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

The enthalpy of vaporization is the energy required to convert a liquid into a gas. The enthalpy of vaporization is also known as the heat of vaporization or the latent heat of vaporization. The enthalpy of vaporization is usually expressed in terms of joules per mole (J/mol) or kilojoules per kilogram (kJ/kg).

For water, the enthalpy of vaporization is 2260 J/mol at 100°C and 4096 kJ/kg at 373.15 K.

The enthalpy of vaporization is the amount of thermal energy required to change a unit mass of liquid into a unit mass of gas. The enthalpy of vaporization is also known as the heat of vaporization or the latent heat of vaporization. The enthalpy of vaporization is usually expressed in units of joules per mole (J/mol) or kilocalories per mole (kcal/mol).

The molar enthalpy of vaporization is sometimes also called the heat content, heat capacity, or specific heat.

## How to Calculate Enthalpy of Vaporization

In order to calculate the enthalpy of vaporization, you need to know the heat of vaporization and the boiling point. The heat of vaporization is the amount of energy required to convert a liquid into a gas. The boiling point is the temperature at which a substance changes from a liquid to a gas.

To calculate the enthalpy of vaporization, you need to subtract the heat of vaporization from the boiling point.

## Enthalpy of Vaporization of Water

The enthalpy of vaporization, also known as the heat of vaporization or latent heat of vaporization, is the amount of thermal energy required to convert a liquid into a gas. The enthalpy of vaporization is usually expressed in terms of the specific heat of the substance, which is the amount of thermal energy required to raise the temperature of 1 gram of the substance by 1 degree Celsius. For water, the specific heat is 4.184 joules per gram-degree Celsius (J/g°C), and the enthalpy of vaporization is 2.257 kilojoules per mole (kJ/mol).

This means that it takes approximately 2256 joules (2204 calories) to convert 1 mole (18 grams) of water from a liquid at 100°C to a gas at 100°C. The enthalpy of vaporization is an important thermodynamic property because it represents the amount of energy that must be added to a liquid in order for it to change states from a liquid to a gas. This energy addition causes an increase in both temperature and pressure, which are necessary for most chemical reactions and processes to occur.

In fact, many industrial processes such as distillation and evaporation rely on this property to separate different substances from each other.

## Enthalpy of Vaporization of Water at 25 C

Water is a molecules made up of two hydrogen atoms and one oxygen atom. When water is in liquid form, the molecules are held together by forces called hydrogen bonds. To turn water into vapor (a gas), energy must be added to break the hydrogen bonds holding the water molecules together.

This process is called vaporization, and the amount of energy needed to vaporize a substance is called its heat of vaporization or enthalpy of vaporization. The enthalpy of vaporization for water at 25 degrees Celsius (77 degrees Fahrenheit) is 2260 joules per mole (J/mol). This means that it takes 2260 J of energy to break the hydrogen bonds in one mole (6.02 x 10^23) of water molecules and turn them into vapor.

The heat of vaporization for water is higher than for most other substances because water has unusually strong Hydrogen bonds. The heat of vaporization plays an important role in many everyday processes. For example, when you sweat, your body uses the heat of vaporization to cool itself off by evaporating sweat from your skin.

Similarly, when you iron clothes, the heating element in the iron adds enough energy to the water molecules in fabric to overcome their hydrogen bonding and cause them to turn into steam.

## Molar Enthalpy of Vaporization

The molar enthalpy of vaporization is the heat required to convert one mole of a liquid into a gas. The enthalpy of vaporization is usually expressed in kJ/mol or J/mol and is often abbreviated as ΔHvap. The molar enthalpy of vaporization can be thought of as the energy required to overcome the intermolecular forces that hold a liquid together.

In order to vaporize, the molecules must first overcome the attractive forces between them. Once they are free from these attractions, they can enter the gas phase. The amount of heat required to break the intermolecular interactions and allow for vaporization is known as the enthalpy of vaporization.

The molar enthalpy of vaporization can be measured using a variety of methods, but most commonly it is determined using a calorimeter. In this type of experiment, a sample of the liquid is placed in a container with anknown quantity of water. The temperature change that occurs when the two substances are mixed is then used to calculate the heat absorbed by the liquid and thus its enthalpy of vaporization.

The value for ΔHvap varies widely depending on the type of substance being considered. For example, water has a ΔHvapof 44 kJ/mol while ethanol has a value closer to 38 kJ/mol. In general, liquids with weaker intermolecular interactions will have lower values for ΔHvap than those with stronger interactions.

This makes sense because it takes less energy to break weaker interactions than it does to break stronger ones.

## Heat of Vaporization of Water in Kj/Mol

The heat of vaporization of water is the amount of energy that must be added to a unit mass of water in order to convert it from a liquid into a gas. The SI unit for this quantity is the joule per mole (J/mol), although it is more commonly expressed in kilojoules per mole (kJ/mol). Water has one of the highest heats of vaporization among all substances, second only to ammonia.

This property is exploited in steam engines, which use water’s high heat of vaporization to convert large amounts of liquid water into steam with a relatively small input of energy. The heat of vaporization decreases with increasing temperature; at temperatures close to the boiling point, it can be approximated by the following equation: ΔHvap(T) = A + BT + CT2 + DT3 − ET−1 where T is temperature in kelvins and ΔHvap is heat of vaporization in kJ/mol.

The coefficients A-E are given in the table below. A B C D E

## What is Enthalpy of Water Vaporization?

The enthalpy of vaporization is the heat required to convert liquid water into steam at a given pressure. The higher the pressure, the more heat is required. The temperature at which this occurs is called the boiling point.

Water vaporization is a endothermic process, meaning it absorbs heat from its surroundings. The reverse process, condensation, releases heat. The standard enthalpy of vaporization (ΔH vap ) is defined as the enthalpy change when one mole of liquid water at its boiling point (100°C) is converted into one mole of steam at 100°C under standard atmospheric pressure (101 kPa).

It has a value of 40.65 kJ/mol. The molar enthalpy of vaporization can be calculated using: ΔH vap = RT ln(P 2 /P 1 ) where R is the gas constant, T is absolute temperature, and P 1 and P 2 are pressures of the initial and final states respectively. At standard conditions (P = 101 kPa), ΔH vap = 40.65 kJ/mol.

Vaporization requires more energy than melting because when water molecules are in theliquid state they are surrounded by other molecules and held together by strong hydrogen bonds. When water changes to a gas, these bonds must be broken and the molecules must escape from each other’s attractions before they can enter into the gaseous state.

## How Do You Calculate the Enthalpy of Vaporization?

Enthalpy of vaporization is the heat required to convert a liquid into a gas. The enthalpy of vaporization is usually expressed in joules per mole (J/mol) or kilocalories per mole (kcal/mol). To calculate the enthalpy of vaporization, you need to know the boiling point of the liquid and the heat of vaporization.

The boiling point is the temperature at which the liquid boils and turns into a gas. The heat of vaporization is the amount of heat required to convert 1 mol of liquid into a gas. The enthalpy of vaporization can be calculated using the following equation:

## What is Enthalpy of Vaporization Give Examples?

The enthalpy of vaporization, also known as the heat of vaporization or latent heat of vaporization, is the amount of thermal energy required to transform a liquid into a gas at a constant temperature. The enthalpy of vaporization is usually expressed in terms of the specific heat (c) and the molar heat of vaporization (ΔHvap): enthalpy change = c × ΔT + ΔHvap

For example, water has a specific heat capacity of 4.184 J/g•K and its enthalpy of vaporization is 2.257 kJ/mol at 100°C. This means that it takes 2260 joules (2.26 kJ) to convert 1 mole (18 grams) of water from a liquid to a gas at 100°C. The enthalpy of vaporization is an important concept in thermodynamics because it provides a way to calculate the change in entropy when a substance changes phase.

The entropy change can be calculated using the equation: ΔS = ΔHvap / T where T is absolute temperature.

## What is Enthalpy of Vaporization Class Ix?

In thermodynamics, the enthalpy of vaporization (also known as the heat of vaporization or evaporation) is the change in enthalpy that accompanies the phase transition from a liquid to a gas at constant temperature and pressure. The enthalpy of vaporization is usually expressed as a function of temperature and is often reported in kJ/mol or J/g. The enthalpy of vaporization plays an important role in many areas of physics and engineering, including atmospheric science, oceanography, and power generation.

In particular, it is used to calculate the energy required to evaporate water from various surfaces, such as soil or vegetation. It can also be used to estimate the amount of water that can be transported through the atmosphere by evaporation. The concept of enthalpy can be applied to any system undergoing a phase transition, but it is most commonly used in relation to liquids and gases.

For example, when water boils, it changes from a liquid to a gas (water vapor), and during this process its enthalpy increases by around 2200 kJ/mol. This increase in enthalpy is due to the fact that water molecules must overcome intermolecular attractions in order to escape from the liquid phase into the gas phase. The term “enthalpy of vaporization” generally refers to the latent heat of vaporization, which isthe heat required per unit mass (or mole) of substance at its boiling point to completely convert it into vapour without increasing its temperature.

However, sometimes other definitions are used; for example, some texts use “enthalpy change” or “heat content change” instead of latent heat when discussing changes between phases at constant pressure.

## Conclusion

The enthalpy of vaporization, also known as the heat of vaporization or latent heat of vaporization, is the amount of energy required to transform a substance from a liquid state into a gaseous state. The enthalpy of vaporization is typically expressed in J/mol or kJ/mol and is often used to compare the strength of different acids and bases.

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.