Chapter 14: Chemical Equilibrium Flashcards
equilibrium is a state of … between ..
balance; opposing processes
equilibrium is a state in which the tendency of the reactants to form products is balanced by the tendency of the
products to form reactants
reversible reactions: a chemical reaction in which the products can react to
re-from the reactants
when a reaction is at equilibrium, it has not
stopped
chemical equilibria are … systems, as opposed to static systems in which processes stop
dynamic
the experimentally determined equilibrium concentrations at the end of each experiment are
the same
law of mass action (equilibrium constant expression): jA + kB lC + mD:
Keq= [C]l[D]m/[A]j[B]k
for a given reaction, Keq is a …
constant at any particular temperature
large values for K signify the reaction is
product favored
product favored: when equilibrium is achieved, most reactant has been
converted to product
small values for K signify the reaction is
reactant favored
reactant favored: when equilibrium is achieved, very little react has been
converted to product
the equilibrium expression for a reverse reaction is the
reciprocal
when the balanced equation for a reaction is multiplied by a factor n, the equilibrium expression for the new reaction is the original expression …
raised to the nth power
Kp=
Kc(RT)^Δn
Δn= total number of moles of gas on the product side-
the total number of moles of gas on the reactant side
the law of mass action not only describes equilibrium systems, but provides important information about
systems not yet at equilibrium
the reaction quotient, Q, has the same algebraic form as Keq, but uses … rather than equilibrium concentrations in the calculations
current concentrations
Comparing Q to Keq enables us to predict the … in which a reaction will proceed to achieve equilibrium
direction
the concentrations of products and reactants change to bring Q
closer in value to Keq
if Q is less than Keq, the reaction proceeds
toward products
If Q > Keq, the reaction proceeds to
form reactants
At equilibrium,
Q = Keq
lechatelier’s principle: when a system at equilibrium is placed under stress, the system will undergo a … in such a way as to …
change; relieve that stress
lechatelier’s principle: the system undergoes a … in order to …
temporary shift; restore equilibrium
lechatelier’s principle can be exploited to
increase the yield of a reaction
if the products of a reaction can be removed from the reaction mixture, the system responds by
producing additional products
shift in equilibrium involves a change in …, not Keq!
composition
as long as these other substances do not react or affect the partial pressures of the reactants or products, the pressures of materials other than the reactants or products have .. on the equilibrium
no effect
changing the temperature of a reaction changes the value of …, in the direction predicted b Le Chatelier’s principle
Keq
increasing the temperature of an exothermic reaction … Keq, so more … form; increasing the temperature of an endothermic reaction … Keq, so more … form
decreases; reactants; increases; products
the concentration of a solid or a pure liquid does not … during the course of a reaction
change
therefore, the concentrations of solids and pure liquids are not ….
included in the expression for the equilibrium constant
if any of the substances in the chemical equation is no longer present, the system is not at equilibrium and it cannot be
described by the law of mass action
heterogenous equilibria are important to study because chemists often strive to make the product in a different phase than the reactants so that the separation of .. is easier
products from reactants
solubility equilibria: reactions that involve the
dissolution and formation of a solid from solution
… are used to describe solubility equilibria
net ionic equations
the solubility of a solid can be calculated from the … and the … for the dissociation of the solid
solubility constant; chemical equation
the solubility product is the equilibrium constant that describes a
solid dissolving to produce ions in solution
solubility depends on both … and the …
Ksp; stoichiometry
common ion effect: a term used to describe the effect of adding a solute to a solution that
contains an ion in common
the solubility of a precipitate is lower in a solution that contains an
ion in common with the substance
in a precipitation reation, the common ion effect predicts …
decreased solubility of a precipitate
When Q exceeds Ksp, a … will form
preciptate
If Q is less than Ksp, then more solid can
dissolve
