## Entropy

Entropy is used to measure n number of ways in which a system’s disorder. Thus, Entropy is used to measure all the system’s thermal energy per unit temperature which is not able to be used for doing the work which is useful. However, work is obtained from ordered molecule motion; the amount of entropy is also measured in the form of the molecular disorder.

### Entropy Calculator

Entropy is associated with a probability. If a system has a number of states that are available to it, if they can achieve the greater number are the best way to occur. That is one of the best states where greater probability has highest entropy.

## Entropy_Calculator

## Steps for Entropy Calculator

**Step 1:**

List all the given values for entropies in the problem.

**Step 2:**

Calculate all the unknown entropy and these values are substituted in the entropy formula.

**S**_{Reaction}**=** **S**_{products}**–** **S**_{Reactants}

_{Step 3:}

Interpret whether the values of entropy is in specified units.

### Problem on Entropy Calculator

Calculate the entropy change for the following reaction.

** PCl _{5 }→ PCl_{3} + Cl_{2} **

Given that

**ΔS _{PCl3 + Cl2 }= 122J/K/mole**

ΔS_{PCl5} = 98J/K/mole

**Step 1:**

Given Data

** ΔS _{PCl3} + Cl2 = 122J/K/mole**

ΔS_{PCl5} = 98J/K/mole

**Step 2:**

ΔS_{Reaction} = 122 – 98

ΔS_{Reaction} = 24J/K/mole

**Step 3: ** The enthalpy change of the reaction is given in J/K/mole units.

**Answer: **

The enthalpy change of the given reaction is 24J/K/mole.