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20 Cards in this Set
- Front
- Back
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System
Surroundings |
Macroscopic body under study
Everything else |
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State functions
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Pathway independent
Number of moles, internal energy, enthalpy, entropy, and Gibbs free energy |
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Two ways to transfer energy between systems
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Heat & work
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Heat (q)
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The movement of energy via conduction, convection or radiation
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Conduction
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Thermal energy transfer via molecular collisions
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Convection
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Thermal energy transfer via fluid movements
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Radiation
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Thermal energy transfer via electromagnetic waves
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Work (w)
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PΔV (at a constant pressure)
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0th Law of Thermodynamics
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Two bodies in equilibrium with the same system are in thermal equilibrium with each other
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1st Law of Thermodynamics
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The energy of an isolated system is conserved for any reaction
ΔE = q + w |
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2nd Law of Thermodynamics
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The entropy of the universe increases for any reaction
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3rd Law of Thermodynamics
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A perfect crystal at zero kelvin is assigned an entropy value of zero. All other substances and all temperatures have a positive entropy value
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S E V E N
State Function of Thermodynamics |
1. Internal energy U
2. Temperature T 3. Pressure P 4. Volume V 5. Enthalpy H 6. Entropy S 7. Gibbs energy G |
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Internal energy
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All possible forms of energy on a molecular scale
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Average kinetic energy of a single molecule in any fluid
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KE = 3/2(kT)
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Enthalpy
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Sum of its internal energy and the product of its pressure and volume
ΔH = ΔU + PΔV (constant pressure) |
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Heat of reaction
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The change in enthalpy from reactants to products
ΔH⁰ (reaction) = ΔHf⁰ (products) - ΔHf⁰ (reactants) ⁰ = Standard state conditions |
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Entropy (S)
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For a closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work.
A measure of the disorder or randomness in a closed system. ΔS (system) + ΔS (surroundings) = ΔS (universe) ≥ 0 |
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What dictates the direction of a reaction
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Entropy
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Gibbs Free Energy (G)
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Free energy is a measure of the capacity of the system to do work. If its value is negative, the system will have a tendency to do work spontaneously, as in an exothermic chemical reaction.
ΔG = ΔH - TΔS |
