Equilibrium: The Extent of Chemical Reactions
The subscript "c" used in the symbols Qc and Kc indicate that these quantitates are based on the ______ of products and reactants.
concentrations
Adding a gaseous reactant
increase in pressure
Le Chatelier's principle states that when a chemical system at equilibrium is disturbed, the system will undergo a net reaction that
minimizes, equilibrium
The equilibrium constant K for a system at equilibrium expresses a particular ratio of equilibrium ______ of products and reactants at a particular _______. The value of K is also equal to the ratio of the rate _____ for the forward and reverse reactions.
concentrations, temperature, constants
In a closed system a reversible chemical reaction will reach a state of dynamic chemical _______ when the rate of the forward reaction is _______ to/than the rate of the reverse reaction.
equilibrium, equal
In a reaction has a relatively _____ value of K and fairly ______ initial concentrations, equilibrium calculations can be simplified by assuming that the change in concentration (x) is _______ compared to [reactant]init. The assumption is justified as long as x is less than ____% of the initial concentration.
low, high, small, 5
To construct the reaction quotient Qc for a given reaction, the _____ concentration placed in the numerator and the _____ concentrations are placed in the denominator. Each term is then raised to the power of its stoichiometric _____ from the balanced equation.
product, reactant, coefficient
Which of the following options correctly describe how a system at equilibrium will respond to change in temperature? Select all that apply.
A change in temperature will cause a change in Kc. If the forward reaction is exothermic, an increase in temperature causes a shift to the left.
intermediate K
Both reactants and products will be present in significant amounts at equilibrium
For a given reaction, Kc is the equilibrium constant based on the molar _____ of reactants and products while Kp is the equilibrium constant based on the partial _____ of reactants and products.
Concentration, Pressures
The law of mass action states that _______.
Equilibrium can be reached from any directions i.e, by beginning with a mixture of reactants or products, or both. A chemical system reaches a state where the concentrations of reactants and products is a constant ratio.
A decrease in temperature causes
K to increase if delta H < 0
Increase in volume
decrease in pressure
Q
expresses a particular ratio of product and reactant concentrations for a reaction at any time
If delta H> 0, K will decrease
when temperature decreases
Which of the following reactants and/or products would not appear in the expression for Q or K for the following reaction? 4HCl + MnO2 <-> MnCl2 + 2H2O +Cl2
H2O, MnO2
An increase in temperate causes
K to increase if delta H > 0
Which of the following is the correct expression for the relationship between Kc and Kp?
Kp=Kc(RT)^Deltan/(gas)
Which of the following changes will cause the equilibrium shown to shift toward the products? Select all that apply. Fe3O4 +4H2 <-> 3Fe +4H2O
Remove H2O from the reaction vessel. Add H2 without changing the volume.
If the equilibrium constant K for a particular reaction is 1.22e14, which of the following statements correctly describes the reaction?
There are large concentrations of products compared to reactants.
An equilibrium calculation can be simplified by taking square roots on both sides of the equation when _______.
both numerator and denominator in the expression for K are perfect squares
K
expresses a particular ratio of product and reaction concentrations for a reaction at equilibrium
If the value of K for the forward reaction is less than 1, the value of K for the reverse reaction is ______ than 1.
greater.
adding a solid
no effect on pressure
The concentration of pure ____ and _____ are not included in the expression for Q or K for a given reaction.
solids, liquids
The value of K for the forward reaction is _______ the value of K for the reverse reaction.
the reciprocal of
if delta H< 0, K will increase
when temperature increases
Which of the following statements are true about the reaction quotient, Q?
Q expresses a particular ratio of products and reactants at any time during reaction. The expression for Q is the same as the expression for K. Q = K only at equilibrium.
The reaction quotient Qc for a particular reaction is given by the expression [X]^a / [Y]^b. Match the components of this expression correctly for the balanced equation 3O2 <-> 2O3
X= O3 a= 2 Y=O2 b=3
If a system at equilibrium is distributed by a change in concentration, the system will shift to _____ a substance that is added and to _______ a substance that has been removed.
use up, produce
Large K
Equilibrium favors the products; there will be more products than reactants at equilibrium
Small K
Equilibrium favors the reactants: there will be more reactants than products at equilibrium
For the following reaction, what will be observed if the volume is increased at constant temperature? Select all that apply. 2NO2 <-> 2NO + O2
The concentration of all species will decrease at the instant the volume is changed. The equilibrium position wil shift toward the products.
adding in inert gas
increase in total pressure, but no change in partial pressures of gases
As a reaction is moving from reactants to products (i.e, from left to right as written) toward equilibrium, the value of Q is
increasing
The law of mass action reflects the observation that an equilibrium state is reached by a chemical system regardless of the ______ concentrations of reacting substances. In other words a chemical system can reach equilibrium either from the reactant or from the _____
initial, products
If a system at equilibrium is disturbed by changing the concentration of a reactant or product, the equilibrium _______ will shift but the ratio of the product to reactant will be _______ once the system reestablishes equilibrium. The value of K will be ______
position, the same, unchanged
The equilbrium constant is a special value of the reaction ______ that occurs when reactant and product concentrations are at their _____ values.
quotient, equilibrium