Chapter 14

Question 1

chemical equilibrium

Answer 1

• a dynamic process in which the concentrations of reactants and products remain constant over time and the rate of the reaction in the forward direction matches its rate in the reverse direction.
• dynamic: As already discussed, unchanging concentrations of reactants and products do not mean that a reaction has stopped. The reaction still proceeds, but it does so equally rapidly in both the forward and reverse directions simultaneously.

Question 2

law of mass action

Answer 2

• the principle relating the balanced chemical equation of a reversible reaction to its mass action expression (or equilibrium constant expression).

Question 3

mass action expression

Answer 3

• an expression equivalent in form to the equilibrium constant expression, but applied to reaction mixtures that may or may not be at equilibrium.

Question 4

equilibrium constant expression

Answer 4

• the ratio of the concentrations or partial pressures of products to reactants at equilibrium, with each term raised to a power equal to the coefficient of that substance in the balanced chemical equation for the reaction.

Question 5

equilibrium constant(K)

Answer 5

• the numerical value of the equilibrium constant expression of a reversible chemical reaction at a particular temperature.
  
  • a ratio of positive values(concs) so K is ALWAYS pos
  • K>1 favors products(has mostly products) at equil
  • K btwn 0 and 1 has few products at equil
  • unitless
• we use concentration and partial pressure values directly in equilibrium calculations. When we do, we are assuming that all the reactants and products are behaving ideally.
• products/reactansts

Question 6

reaction quotient(Q)

Answer 6

• the numerical value of the mass action expression based on the concentrations or partial pressures of the reactants and products present at any time during a reaction.
  
  • At equilibrium, Q = K.
  • Q<k: more products reactant concs higher than at equil>
    <li>Q&gt;K: more reactants, products concs higher than at equil</li></k:>

Question 7

homogenous equilibria

Answer 7

• equilibria that involve reactants and products in the same phase

Question 8

heterogenous equilibria

Answer 8

• equilibria that involved reactants and products in more than one phase
• as long as a liquid is present its conc is considered constant and doesn’t appear in K expression
  
  • pue SOLIDS AND LIQUIDS don’t appear in K=

Question 9

Le Chatlier’s principle

Answer 9

• the principle that a system at equilibrium responds to a stress in such a way that it relieves that stress.