Thermodynamics Study Guide
1. Key Definitions
● System: The part of the universe being studied.
● Surroundings: Everything outside the system.
● Enthalpy (ΔH): Heat content of a system at constant pressure.
● Entropy (ΔS): Measure of disorder/randomness in a system.
● Gibbs Free Energy (ΔG): Determines spontaneity of a process (ΔG = ΔH – TΔS).
2. Important Formulas
● ΔH = q (at constant pressure)
● q = m × c × ΔT → heat transfer (mass × specific heat × temperature change)
● ΔE = q + w → First Law of Thermodynamics
● w = –PΔV → Work done by expansion/compression of gases
● ΔG = ΔH – TΔS → Spontaneity
3. Concepts to Remember
● Exothermic reactions (ΔH < 0): Release heat (e.g., combustion).
● Endothermic reactions (ΔH > 0): Absorb heat (e.g., melting ice).
● Spontaneity: A reaction is spontaneous if ΔG < 0.
● Entropy trends: Gas > liquid > solid (more disorder → higher entropy).
● Calorimetry: Measures heat changes in chemical reactions.
● At equilibrium: ΔG = 0.
1. Key Definitions
● System: The part of the universe being studied.
● Surroundings: Everything outside the system.
● Enthalpy (ΔH): Heat content of a system at constant pressure.
● Entropy (ΔS): Measure of disorder/randomness in a system.
● Gibbs Free Energy (ΔG): Determines spontaneity of a process (ΔG = ΔH – TΔS).
2. Important Formulas
● ΔH = q (at constant pressure)
● q = m × c × ΔT → heat transfer (mass × specific heat × temperature change)
● ΔE = q + w → First Law of Thermodynamics
● w = –PΔV → Work done by expansion/compression of gases
● ΔG = ΔH – TΔS → Spontaneity
3. Concepts to Remember
● Exothermic reactions (ΔH < 0): Release heat (e.g., combustion).
● Endothermic reactions (ΔH > 0): Absorb heat (e.g., melting ice).
● Spontaneity: A reaction is spontaneous if ΔG < 0.
● Entropy trends: Gas > liquid > solid (more disorder → higher entropy).
● Calorimetry: Measures heat changes in chemical reactions.
● At equilibrium: ΔG = 0.
