Thermodynamics Cheat Sheet

Key Definitions

• Thermodynamics: Study of heat, work, and energy transformations. ✅

• System: The part of the universe being studied. ✅

• Surroundings: Everything outside the system. ✅

• Internal Energy (U): Total energy contained within a system. ✅

• Enthalpy (H): Heat content of a system at constant pressure. ✅

Important Concepts

Laws of Thermodynamics

• Zeroth Law: If A is in thermal equilibrium with B, and B with C, then A is in equilibrium with C. ✅

• First Law: Energy cannot be created or destroyed, only transformed. ΔU = Q - W ✅

• Second Law: Heat cannot spontaneously flow from colder to hotter bodies. ✅

• Third Law: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero. ✅

Processes

• Isothermal: Constant temperature. Q = W ✅

• Adiabatic: No heat exchange. ΔU = -W ✅

• Isochoric: Constant volume. ΔU = Q ✅

• Isobaric: Constant pressure. Q = ΔH ✅

Key Formulas

• First Law of Thermodynamics: ΔU = Q - W

• Work Done: W = PΔV ✅

• Enthalpy Change: ΔH = ΔU + PΔV ✅

• Heat Transfer: Q = mcΔT ✅

• m: mass

• c: specific heat capacity

• ΔT: change in temperature

Common Mistakes to Avoid

Common Mistake: Confusing heat (Q) with temperature (T). Remember, heat is energy, while temperature is a measure of thermal energy.

Memory Tricks

Tip: "Q = mcΔT" —

• Q: Heat added

• m: Mass

• c: Specific heat capacity

• ΔT: Change in temperature

Key Diagrams

Thermodynamic Processes:
  Isothermal:   _______
                |     |
                |     |
                |_____|
  
  Adiabatic:    \     /
                 \   /
                  \_/
  
  Isochoric:    |-----|
  
  Isobaric:     ------>