Specific Heat vs Heat of Vaporization: Difference and Comparison

In both specific heat and heat of vaporization, a form of energy is required. In this way, both the processes have some sort of similarity with each other.

But they mostly differ on other grounds, such as in specific heat, the substance’s temperature is changed, whereas, in the heat of vaporization, the physical form of the substance is transformed.

Key Takeaways

1. Specific heat measures the energy required to raise the temperature of a substance by one degree Celsius.
2. Heat of vaporization quantifies the energy needed to change a liquid into vapor at constant temperature and pressure.
3. These two properties are important in understanding the thermal behavior of substances and their practical applications.

Specific Heat vs Heat of Vapourization

Specific heat is the amount of heat energy required to raise the temperature of one unit of mass by one degree Celsius or Kelvin. The heat of vaporization is the amount of heat energy required to convert one unit of mass from its liquid state to its gaseous state at a constant temperature.

Specific heat refers to the amount of energy that we use in a reaction to change the temperature of the substance by one unit. Specific heat is denoted in the equation by the ‘s.’

It means that the change of temperature or the amount of heat absorbed by the substance is equally proportionate to the object’s mass.

The heat of vaporization is used when a substance goes through a physical stage change. So, to attain a different physical state, a substance requires heat.

This specific amount of heat is called the heat of vaporization. In this process, the temperature does not change. It is the physical state of the matter that changes.

Comparison Table

Parameters of Comparison	Specific Heat	Heat of Vapourization
Meaning	Specific heat refers to the required heat to change the temperature of the unit mass of the matter by one.	The heat of vapourization is the amount of heat needed to change the physical state of objects.
Purpose	Specific heat is applied to change the temperature of the matter.	The heat of vapourization is used to change a matter from its liquid state to gaseous and gaseous to liquid.
Temperature	Here, the temperature changes.	But in the heat of vapourization the temperature does not change.
State of matter	Specific heat cannot be applied if the matter is changing its physical state.	The Heat of vapourization is only applied in this case.
Energy	In specific heat, the substance rather absorbs heat than releases it.	In the heat of vapourization, the substance can both absorb and release energy.

What is Specific Heat?

If you have a bowl half full of water and put it on flame, it will take a certain amount of time to get warmed up. But when you fill the whole bowl with water and again put it on flame, it will not take the same amount of time as it had taken in the previous case.

So you need more heat in the second scenario than the first one. This means for the same change of temperature, the amount of heat absorbed by a substance is directly proportional to the object’s mass.

Now, if we take the same amount of water and raise the temperature by a few degrees, we will see some changes. It can be said that more heat was supplied to make a larger change. 

Thus, the amount of heat absorbed by a substance is equal to the amount we get by multiplying the change of temperature, the constant of proportionality with the object’s mass. So, Q = m.s.ΔT.

Here S means specific heat. The value of specific heat can be different for different substances. When the object’s mass and the change in temperature are raised by one unit, the specific heat becomes equal to the amount of heat absorbed by the object.

So the value of ‘s’ denotes the amount of heat energy required to change the temperature of unit mass by one unit.

What is Heat of Vapourization?

Most of the matters go through different phases of change, like ice melting to water. So it changes from its solid physical stage to the liquid form.

When water boils, it changes from its liquid stage to its gaseous form. If we observe our surroundings properly, we will observe that most of the matter exists in its liquid and gaseous form.

To undergo physical changes, a substance needs a specific amount of heat. This heat is called the heat of vaporization.

So it is the specific amount of heat that is needed for the change the physical state of the specific amount of heat required to change the physical state of a substance from its liquid to its gaseous stage at a specified pressure.

This specific heat of vaporization is added to vaporize one gram of a substance at a standard temperature. For example, when you please a pot of water over a burner, with proper heat and pressure, it will start boiling.

Then this boiling water will go through a phase change. That is, the liquid water will change to gaseous water.

During a phase change, a substance absorbs or releases heat. There can be a significant change in the volume of the substance also. For example, the volume of water changes to 1700 fold when it is going through the phase change from liquid to gaseous.

So when water is changed from its liquid to its gaseous form or gaseous to liquid, it causes a change in the state of the substance but not the temperature.

Main Differences Between Specific Heat and Heat of Vapourization

1. Specific heat refers to the amount of heat required to change the temperature of the substance by one unit. The heat of vaporization happens when a substance is going through a phase change.
2. When a substance is going through a phase change, specific heat cannot be applied. But the heat of vaporization only occurs when a substance is experiencing a phase change.
3. Specific heat changes the temperature of the substance. But in the heat of vaporization, the state of the substance changes, not the temperature.
4. Specific heat is not known by any other name. But the developer is also known by the name of latent heat. 
5. In specific heat, energy is absorbed by the substance. Button heat of vaporization the substance can either absorb or release the heat in the process.

References

1. https://aip.scitation.org/doi/abs/10.1063/1.1137207
2. https://journals.aps.org/prb/abstract/10.1103/PhysRevB.4.2029