Gen chem

• Endothermic process


  Process that absorbs heat from the surroundings
• Exothermic process


  Process that gives off heat to the surroundings
• Thermodynamics


  A scientific discipline that deals with the interconversion of heat and other forms of energy
• Enthalpy, H


  A thermodynamic quantity used to describe heat changes taking place at constant pressure
• Enthalpy of reaction, ΔHrxn


  The difference between the enthalpies of the products and the enthalpies of reactants
• Spontaneous process


  A physical or chemical change that occurs by itself. A process that takes place without energy from an external source
• 1st Law - Energy of the universe is constant.

  --_"Energy can be converted from one form to another but cannot be created or destroyed."
• 2nd Law - Entropy of universe increases.

  ---"The entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process."
• 3rd Law - At absolute zero, the entropy of a perfect crystal is 0

  --"The entropy of a perfect crystalline substance is zero at

  the absolute zero of temperature (T = 0 K= -273.15 oC)."

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• • Entropy, S
  • ---A thermodynamic quantity that is a measure of how spread out or dispersed the energy of a system is among the different possible ways that system can contain energy
• • Absolute Entropy
  • ---The absolute value of entropy of a substance
• • Standard entropy, S°
  • --The absolute entropy of a substance at 1 atm and 25 °C
• • Gibbs Free Energy, G
  • -- Energy available to do useful work. Used to express the spontaneity of a reaction more directly
• • Standard Free Energy, AGrxn
  • The free energy change for reaction when it occurs under standard state conditions, when reactants in their standard states are converted into products in their standard states
• • Equilibrium constant, K
  • A number equal to the ratio of the equilibrium concentrations of the products to the equilibrium concentrations of reactants, each raised to the power of their stoichiometric coefficients
• • State functions
  • Properties that can be expressed as (final - initial) states
• • A spontaneous process is a physical or chemical change that occurs by itself. These processes occur without requiring an outside force and continue until equilibrium is reached.
• • Entropy, S, is a thermodynamic quantity that is a measure of how spread out or dispersed the energy of a system is among the different possible ways that system can contain energy.