Genchem weeks 3-4

• Equilibrium is denoted by ⇌
• Reaction Quotient is calculated to determine whether a reaction proceeds in a forward or in a reverse direction.
• Reaction Quotient

  Qc < Kc then the reaction proceeds on a forward direction
• Reaction Quotient

  Qc > Kc then the reaction proceeds on a reverse direction
• Reaction Quotient

  Qc = Kc then the reaction is at equilibrium
• Homogeneous Equilibria

  Reactions in which all reaching species are in the

  same phase
• Heterogeneous Equilibria

  A reversible reaction involving reactant and

  products that are in the different phase
• POINTS TO REMEMBER IN CALCULATING KC:

  • Kc is constant for specific temperature. If you

  change the temperature of a reaction, then Kc

  also changes.

  • Pure solids and pure liquids, including

  solvents, are not included in the equilibrium

  expression.

  • Kc is often written without units, depending

  on the textbook.

  • The reaction must be balanced with the

  coefficients written as the lowest possible

  integer values in order to get the correct

  value for Kc.
• Another term is Kp,

  It is also products / reactants but uses a

  pressure or gas instead of

  concentration.