Question

What is the modified latent heat of vaporization? For what is it used? How does it differ from the ordinary latent heat of vaporization?

Short answer

Answer: The main difference between the modified latent heat of vaporization and the ordinary latent heat of vaporization lies in the inclusion of sensible heat. Modified latent heat factors in the energy required to raise the temperature of a substance to its boiling point in addition to the energy required for phase change, while the ordinary latent heat strictly refers to the energy needed to undergo a phase change from liquid to vapor state at the boiling point, without considering the temperature change.

Step-by-step solution

Understanding Latent Heat of Vaporization

The latent heat of vaporization is the amount of heat required to convert a given mass of liquid at its boiling point to a vapor without changing its temperature. It is used to describe and quantify the energy needed in phase changes involving a substance's transition between the liquid and vapor states.

Introducing Modified Latent Heat of Vaporization

The modified latent heat of vaporization refers to the amount of heat required to transform a liquid into a vapor when the temperature of the liquid is below its boiling point. In this case, an added component of sensible heat is considered, which is the heat needed to bring the substance to its boiling point before the phase transition occurs. In other words, modified latent heat encompasses both sensible heat (raising the temperature) and actual latent heat (phase change).

Usage of Modified Latent Heat of Vaporization

Modified latent heat of vaporization is used in various applications like power generation, refrigeration, and air conditioning systems. It is particularly helpful in understanding and designing systems that operate below boiling points or those that work with a combination of phase changes and temperature changes. The consideration of modified latent heat allows engineers and scientists to accurately calculate heat exchange and energy requirements for various scenarios where the temperature of the liquid is below the boiling point.

Difference between Ordinary Latent Heat and Modified Latent Heat of Vaporization

The primary difference between the ordinary latent heat and the modified latent heat of vaporization lies in the inclusion of sensible heat. The ordinary latent heat of vaporization strictly refers to the energy needed to undergo a phase change from liquid to vapor state at the boiling point, without considering the temperature change. Conversely, modified latent heat factors in the energy required to raise the temperature of a substance to its boiling point in addition to the energy required for phase change.