GENERAL CHEMISTRY II - EXAM 2
QUESTIONS AND ANSWERS
Dynamic Equilibrium - Correct Answers -For a chemical reaction, the condition in which
the rate of the forward reaction equals the rate of the reverse reaction.
Equilibrium Constant (K) - Correct Answers -The ratio (at equilibrium) of the
concentrations of the products raised to their stoichiometric coefficients divided by the
concentrations of the reactants raised to their stoichiometric coefficients.
aA+bB↔cC+dD
K=([C]^c[D]^d)/([A]^a[B]^b)=[products]/[reactants]
Relative Size of Keq - Correct Answers -If K>>1, reaction proceeds forward; favors
products
If K<<1, reaction proceeds a little; favors reactants
If K≈1, reaction proceeds about half way
Relationships Between Keq and the Chemical Equation - Correct Answers -If the
reaction is reversed: Kreverse = 1/Kforward
If the coefficients in the equation are multiplied by a factor: raise the equilibrium
constant to the same factor
If two or more individual chemical equations are added: multiply the corresponding
equilibrium constants by each other to obtain the overall Keq
Heterogeneous Equilibria Involving Solids and Liquids - Correct Answers -The
concentrations of pure liquids and solids remain constant and are therefore excluded
from the equilibrium expression.
Expressing Keq in Terms of Pressure - Correct Answers -Kp=Kc(RT)^(∆n)
where Kp is the equilibrium constant with respect to partial pressures in atm, Kc is the
equilibrium constant with respect to concentration, R=0.08206 L·atm/mol·K, T is
temperature in K, and ∆n is the change in number of moles of gas
Reaction Quotient (Qc) - Correct Answers -the ratio (at any point in the reaction) of the
concentrations of the products raised to their stoichiometric coefficients divided by the
concentrations of the reactants raised to their stoichiometric coefficients.
, Q, K, and the Direction of a Reaction - Correct Answers -If Q<K, reaction goes forward
(toward products)
If Q=K, reaction is at equilibrium
If Q>K, reaction goes backwards (toward reactants)
Le Châtelier's Principle - Correct Answers -When a chemical system at equilibrium is
disturbed, the system shifts in a direction that minimizes the disturbance.
Summary of Le Châtelier's Principle: Changes in Pressure - Correct Answers -
Decreasing the volume causes the reaction to shift in the direction that has the fewer
moles of gas particles.
Increasing the volume cases the reaction to shift in the direction that has the greater
number of moles of gas particles.
If a reaction has an equal number of moles of both sides of the chemical equation, then
a change in volume produces no effect on the equilibrium.
Adding an inert gas to the mixture at a fixed volume has no effect on the equilibrium.
Summary of Le Châtelier's Principle: Changes in Concentration - Correct Answers -
Increasing the concentration of one or more of the reactants (which makes Q<K) causes
the reaction to shift in the direction of the products.
Increasing the concentration of one or more of the products (which makes Q>K) causes
the reaction to shift in the direction of the reactants.
Decreasing the concentration of one or more of the reactants (which makes Q>K)
causes the reaction to shift in the direction of the reactants.
Decreasing the concentration of one or more of the products (which makes Q<K)
causes the reaction to shift in the direction of the products.
Summary of Le Châtelier's Principle: Changes in Temperature - Correct Answers -In an
exothermic reaction:
Increasing the temperature causes an exothermic reaction to shift in the direction of the
reactants; the value of Keq decreases.
Decreasing the temperature causes an exothermic reaction to shift in the direction of
the products; the value of Keq increases.
In an endothermic reaction:
Increasing the temperature causes an endothermic reaction to shift in the direction of
the products; the value of Keq increases.
Decreasing the temperature causes an endothermic reaction to shift in the direction of
the reactants; the value of Keq decreases.
General Properties of Acids - Correct Answers -sour taste, ability to dissolve many
metals, ability to turn blue litmus paper red, ability to neutralize bases
HCl - Correct Answers -Hydrochloric Acid; a common acid
NaOH - Correct Answers -Sodium Hydroxide; a common base
QUESTIONS AND ANSWERS
Dynamic Equilibrium - Correct Answers -For a chemical reaction, the condition in which
the rate of the forward reaction equals the rate of the reverse reaction.
Equilibrium Constant (K) - Correct Answers -The ratio (at equilibrium) of the
concentrations of the products raised to their stoichiometric coefficients divided by the
concentrations of the reactants raised to their stoichiometric coefficients.
aA+bB↔cC+dD
K=([C]^c[D]^d)/([A]^a[B]^b)=[products]/[reactants]
Relative Size of Keq - Correct Answers -If K>>1, reaction proceeds forward; favors
products
If K<<1, reaction proceeds a little; favors reactants
If K≈1, reaction proceeds about half way
Relationships Between Keq and the Chemical Equation - Correct Answers -If the
reaction is reversed: Kreverse = 1/Kforward
If the coefficients in the equation are multiplied by a factor: raise the equilibrium
constant to the same factor
If two or more individual chemical equations are added: multiply the corresponding
equilibrium constants by each other to obtain the overall Keq
Heterogeneous Equilibria Involving Solids and Liquids - Correct Answers -The
concentrations of pure liquids and solids remain constant and are therefore excluded
from the equilibrium expression.
Expressing Keq in Terms of Pressure - Correct Answers -Kp=Kc(RT)^(∆n)
where Kp is the equilibrium constant with respect to partial pressures in atm, Kc is the
equilibrium constant with respect to concentration, R=0.08206 L·atm/mol·K, T is
temperature in K, and ∆n is the change in number of moles of gas
Reaction Quotient (Qc) - Correct Answers -the ratio (at any point in the reaction) of the
concentrations of the products raised to their stoichiometric coefficients divided by the
concentrations of the reactants raised to their stoichiometric coefficients.
, Q, K, and the Direction of a Reaction - Correct Answers -If Q<K, reaction goes forward
(toward products)
If Q=K, reaction is at equilibrium
If Q>K, reaction goes backwards (toward reactants)
Le Châtelier's Principle - Correct Answers -When a chemical system at equilibrium is
disturbed, the system shifts in a direction that minimizes the disturbance.
Summary of Le Châtelier's Principle: Changes in Pressure - Correct Answers -
Decreasing the volume causes the reaction to shift in the direction that has the fewer
moles of gas particles.
Increasing the volume cases the reaction to shift in the direction that has the greater
number of moles of gas particles.
If a reaction has an equal number of moles of both sides of the chemical equation, then
a change in volume produces no effect on the equilibrium.
Adding an inert gas to the mixture at a fixed volume has no effect on the equilibrium.
Summary of Le Châtelier's Principle: Changes in Concentration - Correct Answers -
Increasing the concentration of one or more of the reactants (which makes Q<K) causes
the reaction to shift in the direction of the products.
Increasing the concentration of one or more of the products (which makes Q>K) causes
the reaction to shift in the direction of the reactants.
Decreasing the concentration of one or more of the reactants (which makes Q>K)
causes the reaction to shift in the direction of the reactants.
Decreasing the concentration of one or more of the products (which makes Q<K)
causes the reaction to shift in the direction of the products.
Summary of Le Châtelier's Principle: Changes in Temperature - Correct Answers -In an
exothermic reaction:
Increasing the temperature causes an exothermic reaction to shift in the direction of the
reactants; the value of Keq decreases.
Decreasing the temperature causes an exothermic reaction to shift in the direction of
the products; the value of Keq increases.
In an endothermic reaction:
Increasing the temperature causes an endothermic reaction to shift in the direction of
the products; the value of Keq increases.
Decreasing the temperature causes an endothermic reaction to shift in the direction of
the reactants; the value of Keq decreases.
General Properties of Acids - Correct Answers -sour taste, ability to dissolve many
metals, ability to turn blue litmus paper red, ability to neutralize bases
HCl - Correct Answers -Hydrochloric Acid; a common acid
NaOH - Correct Answers -Sodium Hydroxide; a common base
