MCAT Gen Chem 2

Whether or not a process or reaction can occur.

How fast or slow a process or rection can occur.

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

• 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

• Molecular collisions along a conduit
• Analogous to current flow through a wire or H₂O through a pipe

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

C = q/∆T

Is for a given substance only and is defined as the heat capacity per unit mass.

q = mc∆T

• 1.0 cal/g˚C
• or
• 4.18 J/g˚C

• ∆E = q + w
• Work done on the system (+)
• Work done by the system (–)

• Heat cannot be changed completely into work in a cyclical process
• Entropy in an isolated system can never decrease

Pure substances at absolute zero have an entropy of zero

Temperature exists

• 0˚ C = 273.15 K
• -273.15˚ C = 0 K
• Absolute zero = 0 K

• KE = 3/2kT
• k = Boltzman's constant (1.3806503 e ^–23 m2 kg s-2 K-1)

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

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

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

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

Increased randomness, energy released and available to do work

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

• 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)

∆G = the amount of "free" or "useful" energy available to do work.

• -∆G = Spontaneous; exothermic
• +∆G = Non-spontaneous; endothermic

• 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

∆G = ∆H - T∆S

• ∆G - Gibbs
• ∆H - Enthalpy
• ∆S - Entropy
• T - Temp K

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