1 : First Law of Thermodynamics:

• ∆U = q - W
• The change in internal energy (∆U) of a system is equal to the heat (q) added to the system minus the work (W) done by the system on its surroundings.

2 : Enthalpy (H):

• H = U + PV
• Enthalpy is the sum of internal energy and the product of pressure (P) and volume (V).

3 : Standard Enthalpy Change (∆H°):

• ∆H° = ∑(∆H°f(products)) - ∑(∆H°f(reactants))
• It represents the change in enthalpy for a chemical reaction at standard conditions. It is related to the standard enthalpies of formation (∆H°f) of products and reactants.

4 : Standard Entropy (S°):

• S° is the measure of disorder in a system. It is often given in J/(mol•K).

5 : Gibbs Free Energy (∆G):

• ∆G = ∆H - T∆S
• Gibbs free energy is a measure of the spontaneity of a process. If ∆G is negative, the process is spontaneous.

6 : Gibbs-Helmholtz Equation:

• ∆G = ∆H - T∆S
• ∆G = ∆G° + RT ln(Q)
• This equation relates the Gibbs free energy change to enthalpy, entropy, temperature (T), and the reaction quotient (Q).

7 : Van’t Hoff Equation:

• ln(K2/K1) = -(∆H°/R) * (1/T2 - 1/T1)
• The Van’t Hoff equation relates equilibrium constants (K) to temperature changes (∆T) and the enthalpy change (∆H°).

8 : Second Law of Thermodynamics:

The entropy of an isolated system tends to increase over time, leading to greater disorder and randomness.

9 : Third Law of Thermodynamics:

The entropy of a perfectly crystalline substance at absolute zero temperature is zero.

10 : Entropy Change in an Irreversible Process:

• ∆S ≥ q/T
• This equation relates the change in entropy to heat exchange and temperature for an irreversible process.

11 : Clausius-Clapeyron Equation:

• ln(P2/P1) = (∆Hvap/R) * (1/T1 - 1/T2)
• This equation relates vapor pressure, enthalpy of vaporization, and temperature.

12 : Relationship between ∆G° and K:

• ∆G° = -RT ln(K)
• This equation relates the standard Gibbs free energy change to the equilibrium constant (K).

13 : Work Done in Expansion or Compression of Gases:

• W = -P∆V
• For a reversible isothermal process, W = -nRT ln(Vf/Vi)

14 : Relationship between ∆G° and ∆G:

∆G = ∆G° + RT ln(Q)

If ∆G < 0, the reaction is spontaneous.

15 : Hess’s Law:**

• The enthalpy change for a chemical reaction is independent of the pathway taken from reactants to products