JEE & NEET Advanced Masterclass

Thermodynamics & Entropy-Enthalpy Sandbox

Analyze spontaneity criteria, Enthalpy ($\Delta H$), Entropy ($\Delta S$), and Gibbs Free Energy ($\Delta G$) behavior across changing temperatures in real-time.

Reaction Thermodynamic Chamber

Particle dispersion visualizes System Entropy ($S$), while kinetic energy variations map Enthalpy ($\Delta H$).

Gibbs Energy ($\Delta G$): 0 kJ/mol
Spontaneity Status: Spontaneous

1. Fundamental Laws of Thermodynamics

Essential framework for evaluating system energy transformations and state functions:

  • First Law ($\Delta U = q + w$): Law of conservation of energy. Internal energy is a state function; work and heat are path functions.
  • Second Law ($\Delta S_{\text{univ}} > 0$): For any spontaneous process, total entropy of the universe must continuously increase.
  • Third Law: The entropy of a perfectly crystalline pure substance approaches zero at absolute zero ($0\text{ K}$).
$\Delta S_{\text{univ}} = \Delta S_{\text{sys}} + \Delta S_{\text{surr}} > 0$

2. Gibbs Free Energy ($\Delta G$) Criteria

The master criterion for predicting chemical reaction spontaneity at constant temperature and pressure:

$\Delta G = \Delta H - T\Delta S$

High-Yield JEE/NEET Matrix:

  • $\Delta H < 0, \Delta S > 0$: Spontaneous at all temperatures.
  • $\Delta H > 0, \Delta S < 0$: Non-spontaneous at all temperatures.
  • $\Delta H < 0, \Delta S < 0$: Spontaneous at low temperatures ($T < \Delta H/\Delta S$).
  • $\Delta H > 0, \Delta S > 0$: Spontaneous at high temperatures ($T > \Delta H/\Delta S$).

3. Enthalpy, Entropy & Equilibrium Link

Connects thermodynamics directly to chemical equilibrium constants and non-expansion work:

  • Standard Free Energy: $\Delta G^\circ = -RT \ln K_{eq}$
  • Temperature Dependence: van 't Hoff equation links enthalpy change to equilibrium constants at different temperatures.
  • Enthalpy ($\Delta H$): Heat absorbed or released at constant pressure ($\Delta H = \Delta U + P\Delta V$).
$\Delta G = \Delta G^\circ + RT \ln Q$

About this simulation

Use the simulation to connect thermodynamic quantities with physical and chemical processes. The explanations define the equations and clarify the assumptions of the simplified model.

First law

With the chemistry convention, ΔU = q + w. Internal-energy change equals heat transferred to the system plus work done on it.

Enthalpy

H = U + PV. At constant pressure with only pressure-volume work, qp is related to ΔH. Enthalpy is a state function.

Entropy

For a reversible process, dS = δqrev/T. The second law gives a direction to spontaneous processes through total entropy change.

Gibbs energy

At constant temperature and pressure, ΔG = ΔH − TΔS. ΔG < 0 indicates a thermodynamically favorable forward direction under stated conditions.

How to use

Change one parameter at a time, observe the calculated values, and explain trends from the equations.

Limitations

Real systems may involve non-ideal behavior, phase transitions, heat losses, changing heat capacities, and composition-dependent properties.