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
Specific Heat of Water
1.0 cal/g˚C
or
4.18 J/g˚C
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 s-2 K-1)
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 = Non-spontaneous; 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