Equilibrium

Question 1

when reaction reaches state in which energy is minimized and entropy is maximized; chemical equilibria are dynamic (reactions occur at constant rate); rate of forward reaction equals rate of reverse reaction; concentration of products equals concentration of reactants

Answer 1

reversible reaction

Question 2

gives the expression for the equilibrium constant, K(eq); the reaction quotient, Q, has the same form but can be calculated at any concentrations of reactants and products; only gaseous and aqueous species included, pure solids and liquids do not appear

Answer 2

law of mass action

Question 3

the ratio of products to reactants at equilibrium with each species raised to its stoichiometric coefficient; constant for a reaction at constant temperature

Answer 3

equilibrium constant (K(eq))

Question 4

a calculated value that relates the reactant and product concentrations at any given time during a reaction

Answer 4

reaction quotient (Q)

Question 5

provides information about where the reaction is with respect to its equilibrium state

Answer 5

comparison of Q and K(eq)

Question 6

if Q < K(eq)

Answer 6

∆G < 0, and the reaction proceeds in the forward direction

Question 7

if Q = K(eq)

Answer 7

∆G = 0, and the reaction is in dynamic equilibrium

Question 8

if Q > K(eq)

Answer 8

∆G > 0, and the reaction proceeds in the reverse direction

Question 9

determines the balance of a reaction and whether the amount that has reacted can be treated as negligible when compared to other concentrations

Answer 9

magnitude of K(eq)

Question 10

magnitude of K(eq):

indicates the products are present in greater concentrations at equilibrium

Answer 10

if K(eq) > 1

Question 11

magnitude of K(eq):

indicates products and reactants are both present at equilibrium at reasonably similar levels

Answer 11

if K(eq) ≈ 1

Question 12

magnitude of K(eq):

indicates the reactants are present in greater concentrations at equilibrium

Answer 12

if K(eq) < 1

Question 13

magnitude of K(eq):
the amount of reactants that have been converted to products can be considered negligible in comparison to the initial concentration of reactants

Answer 13

if K(eq) &laquo_space;1

Question 14

states that when a chemical system experiences a stress, it will react so as to restore equilibrium

Answer 14

Le Châtelier’s principle

Question 15

the three main types of stresses applied to a system:

Answer 15

changes in concentration, pressure and volume, and temperature

Question 16

increasing reactants or decreasing products shifts reaction to the right, increasing products or decreasing reactants shifts reaction to the left

Answer 16

concentration

Question 17

increasing pressure (or decreasing volume) will shift reaction to the side with fewer moles of gas; decreasing pressure (or increasing volume) will shift reaction to the side with more moles of gas

Answer 17

pressure (on a gaseous system)

Question 18

increasing the temperature of an endothermic reaction or decreasing the temperature of an exothermic reaction will shift the reaction to the right; decreasing the temperature of an endothermic reaction or increasing the temperature of an exothermic reaction will shift the reaction to the left

Answer 18

temperature

Question 19

products that are higher in free energy and can form at lower temperatures; sometimes termed “fast” products because they form more quickly under such conditions

Answer 19

kinetic products

Question 20

products that are lower in free energy and are more stable; pathway proceeds more slowly, but is more spontaneous (more negative ∆G)

Answer 20

thermodynamic product