MCAT Gen Chem 2
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Thermodynamic
Whether or not a process or reaction can occur.

Kinetic
How fast or slow a process or rection can occur.

Exothermic energy coordinate diagram

Endothermic energy coordinate diagram

Convection
Fluid movement caused by the hotter portions of a fluid rising and the cooler portions of a fluid sinking.

Radiation
 Electromagnetic waves emitted from a hot body into the surrounding environment.
 Light colors radiate and absorb less
 Dark colors radiate and absorb more
 Black Body Radiator  perfect theoretical radiator

Conduction
 Molecular collisions along a conduit
 Analogous to current flow through a wire or H_{2}O through a pipe

Heat Capacity (definition)
The amount of energy (in Joules or Calories) a system can absorb per temperature unit (J/K or cal/˚C).

Heat Capacity (formula)
C = q/∆T

Specific Heat Capacity (definition)
Is for a given substance only and is defined as the heat capacity per unit mass.

Specific Heat Capacity (formula)
q = mc∆T


First Law of Thermodynamics
 ∆E = q + w
 Work done on the system (+)
 Work done by the system (–)

Second Law of Thermodynamics
 Heat cannot be changed completely into work in a cyclical process
 Entropy in an isolated system can never decrease

Third Law of Thermodynamics
Pure substances at absolute zero have an entropy of zero

Zeroth Law of Thermodynamics
Temperature exists

Celsius – Kelvin conversion
 0˚ C = 273.15 K
 273.15˚ C = 0 K
 Absolute zero = 0 K

Kinetic Energy of Gasses (formula)
 KE = 3/2kT
 k = Boltzman's constant (1.3806503 e ^{–}^{23} m2 kg s2 K1)

Enthalpy
 (∆H)
 The energy contained within chemical bonds or HEAT

Entropy
 (∆S)
 A measure of the randomness or disorder in a system

Standard State
 Standard State is 25˚ C (298K) and ∆H = 0
 *For thermodynamics problems

STP
 STP (standard temperature and pressure) is 0˚ Celsius (273K) and 1 atm
 *For gas problems

+ ∆S =
Increased randomness, energy released and available to do work

– ∆S =
Decreased randomness, energy is required to "create" increased order and that energy is thus unavailable to do work

Entropy (∆S) increases with: (5 things)
 1. Increased number of items/particles/etc. (Gas trumps # of moles or particles. This means that if two moles of reactants makes one mole of product and that product is a gas, it is still +∆S)
 2. Increased volume
 3. Increased temperature
 4. Increased disorder
 5. Decreased pressure (the higher the pressure the more packing and order of molecules)

Gibbs Free Energy (∆G)
∆G = the amount of "free" or "useful" energy available to do work.
 ∆G = Spontaneous; exothermic
 +∆G = Nonspontaneous; endothermic

Rate Order Graphs
 0 order: [A] vs. time is linear with slope k
 1st order: ln[A] vs. time is linear with slope k
 2nd order: 1/[A] vs. time is linear with slope k
 3rd order: 1/2[A]2 vs. time is linear with slope k

Fundamental Thermodynamic Relation formula
∆G = ∆H  T∆S
 ∆G  Gibbs
 ∆H  Enthalpy
 ∆S  Entropy
 T  Temp K

Entropy signs
 (+) means more disorder or increased entropy.
 (–) means more order or decreased entropy.