Enthalpy and Entropy – Equation, Standard Condition, Characteristics and Calculation

# Enthalpy and Entropy – Equation, Standard Condition, Characteristics and Calculation

## A Guide to Enthalpy and Entropy

Enthalpy is a measure of the internal energy of a system, while entropy is a measure of the disorder of a system. The two concepts are related by the second law of thermodynamics, which states that entropy always increases over time.

Enthalpy is a measure of the energy that is available to do work in a system. It is calculated by adding up the energy of the system’s particles. Entropy is a measure of the disorder of a system. It is calculated by counting the number of different ways that the system’s particles can be arranged.

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The second law of thermodynamics states that entropy always increases over time. This law is due to the fact that entropy is a measure of the disorder of a system, and disorder always increases over time.

## What is Enthalpy?

The enthalpy of a system is the heat content of the system. The enthalpy of a system is the sum of the internal energy of the system and the product of the pressure and the volume of the system.

## Change in Enthalpy

The change in enthalpy is a measure of the heat energy transferred in a chemical reaction. It is calculated by subtracting the enthalpy of the products from the enthalpy of the reactants. Enthalpy is a measure of the internal energy of a system and is determined by the temperature and pressure of the system.

## Standard Enthalpy Change

Standard enthalpy change (enthalpy of formation) is the enthalpy change that accompanies the formation of one mole of a substance from its constituent elements in their standard states. This value is usually given in kilojoules per mole (kJ/mol) or in kilocalories per mole (kcal/mol). The standard enthalpy change for the formation of a gas is zero, because the enthalpy of a gas is determined only by its temperature and pressure.

## Standard Enthalpy Change of Formation

The standard enthalpy change of formation (ΔH f °) is the enthalpy change that occurs when 1 mole of a substance is formed from its elements in their standard states.

ΔH f ° =enthalpy change when 1 mole of a substance is formed from its elements in their standard states

## Standard Enthalpy Change of Combustion

Standard Enthalpy Change of Combustion is the enthalpy change that occurs when 1 mole of a substance is completely burned in oxygen.

## What is Entropy?

The entropy of a system is a measure of its disorder. The higher the entropy of a system, the more disorder there is in it.

## Absolute Entropy

The absolute entropy of a system is the entropy of the system in its most disordered state.

## Entropy Characteristics

The entropy of a system is a measure of its disorder. The higher the entropy of a system, the more disorder there is.

The entropy of a system can be increased by adding energy to the system, by adding new particles to the system, or by increasing the temperature of the system.

The entropy of a system can be decreased by removing energy from the system, by removing particles from the system, or by decreasing the temperature of the system.

## Calculation of Entropy

The entropy of a system is a measure of its disorder. It is calculated by taking the natural log of the number of microstates that are possible for the system.

S = ln(W)

## Enthalpy and Entropy Relation

The enthalpy and entropy of a system are related by the equation:

$H = S + PV$

Where:

H is the enthalpy

S is the entropy

P is the pressure

V is the volume

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