Science

Difference between Entropy and Enthalpy

Main difference

Thermodynamics is the branch of physics that deals with the study of heat and other related phenomena. It also deals with the relationships of heat with other forms of energy, such as electrical, mechanical, or chemical energy. Entropy and enthalpy are the famous terms related to thermodynamics. Entropy is the measure of disorder or randomness in the system during the chemical process, while enthalpy measures the heat change or internal energy change of a system during the chemical reaction under constant pressure. In reality, enthalpy is the measure of the total energy in the system, although it always denotes the change in the energy system at constant pressure, since the total enthalpy of the system cannot be measured, it is measured in joules per kilogram. On the other hand, entropy is the measure of random activity, That is usually the amount of clutter in the system. The SI unit for entropy (S) is Joules per Kelvin (J / K).

Comparative chart

Entropy Enthalpy
Definition Entropy is the measure of disorder or randomness in the system during the chemical process. Enthalpy measures the heat change or internal energy change of a system during the chemical reaction at constant pressure.
SI unit Unit joule per kelvin (J / K) The SI unit for specific enthalpy is Joule per kilogram.
Formula S = q / T H = U + PV

What is entropy?

Entropy is the measure of disorder or randomness in the system during the chemical process. It is actually the measure of random activity, which is usually the amount of disorder in the system. As we know that the energy of a body indicates its ability to do work, the energy of a body can be of any type. It can be mechanical, chemical, thermal, nuclear or any other kind of energy. The measure of that change in energy or disorder during the chemical process is entropy. ‘S’ denotes entropy, and is always capitalized. In an equation, it is written as ‘ΔS’ since it represents the disorder in entropy during the chemical process. The SI unit for Entropy (S) is Joules per Kelvin (J / K). Temperature in the entropy equation is measured on the absolute temperature scale, or Kelvin.

What is enthalpy?

Enthalpy measures the heat change or internal energy change of a system during the chemical reaction at constant pressure. Enthalpy is the measure of the total energy in the system, although it always denotes the change in the energy system at constant pressure, since the total enthalpy of the system cannot be measured. Enthalpy is denoted as ‘ΔH,.’ Talk about the difference between the enthalpy of products and the enthalpy of reactants. It is measured in units of Jmol -1 . The word enthalpy is derived from the Greek word ‘enthalpos’, which means ‘to put heat in’. The word “enthalpy” for this measurement was coined by a famous 19th century physicist , Heike Kamerlingh Onnes. It is generally measured in joules per kilogram.

Entropy vs. Enthalpy

  • Entropy is the measure of disorder or randomness in the system during the chemical process, while enthalpy measures the heat change or internal energy change of a system during the chemical reaction under constant pressure.
  • Actually, enthalpy is the measure of the total energy of the system, while entropy is the measure of random activity, which is usually the amount of disorder in the system.
  • The word ‘enthalpy’ for this measure was coined by a 19 th famous physicist Heike Kamerlingh Onnes century, however, the German physicist Rudolf Clausius coined the word ‘entropy’.

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