SB Introduction to Equilibrium & Equilibrium Expressions

True or false: When two chemical equations are added together,

False

Which of the following options correctly describes the units of Q and K for a reaction?

K and Q are dimensionless quantities.

Which of the following is the correct expression for the relationship between Kc and KP?

KP = Kc(RT)Δn(gas)

Select the correct expression for Kc for the reaction 2PbO (s) + O2 (g) ⇌ 2PbO2 (s).

Kc = 1/[O2]

Which of the following correctly describes the relationship between the equilibrium constant K for a reaction and the rate constants for the forward and reverse reactions at equilibrium?

Kc = kf /kr

As a reaction proceeds, the value of Q _____.

increases or decreases, as necessary, until it reaches the value of K

What is the balanced equation that corresponds to the reaction quotient expression shown?

N2(g) + 2H2(g) ⇄ N2H4(g)

Select the correct expression for the equilibrium constant for the overall reaction when multiple chemical equations are added together.

koverall = k1 × k2 × k3 ×...

What is the correct expression for Kc for the reaction 2POCl3 (g) ⇌ 2PCl3 (g) + O2 (g)?

[PCl3]2[O2]/[POCl3]2

If the value of KC for the forward reaction is less than 1, the value of KC for the reverse reaction is _____ than 1.

greater

The value of KC for the forward reaction is _____ the value of KC for the reverse reaction.

the reciprocal of

Given the balanced equation 2PbO (s) + O2 (g) ⇌ 2PbO2 (s), calculate the value of Δn.

-1

Given the following reaction, which concentration terms appear in the numerator of the reaction quotient, Q, expression?

-CCl4 -HF

Given the following reaction, which concentration terms appear in the denominator of the expression for Kc?

-CFCl3 -HCl

Match each of the following equations to the correct value for Δn. -Δn = 0 -Δn = -1 -Δn=1

-H2 -3O2 -CO2

Which of the following statements correctly describe the equilibrium constant K? Select all that apply.

-K expresses a particular ratio of equilibrium concentrations of products and reactants. -The expression for K has the general form [products]/[reactants] -The value of K is characteristic of a particular equilibrium system.

Which of the following equilibrium expressions are correct for the reaction, 2SO2(g) + O2(g) ⇄ 2SO3(g)? Choose all that apply.

-KP =(PSO3)2/(PSO2)2(PO2) -KC = [SO3]2/[SO2]2[O2]

Match the chemical reaction changes to the corresponding equilibrium constant changes for the reaction A(g) ⇄ B(g). -3A(g) ⇄ 3B(g) -B(g) ⇄ A(g) -2B(g) ⇄ 2A(g)

-Kc13 -1/KC1 -1/(KC1)2

Which of the following reactants and/or products would NOT appear in the expression for K for the following reaction?

-MnO2 -H2O

The equilibrium constant Kc for a particular reaction is given by the expression -X -a -Y -b

-O3 -2 -O2 -3

Which of the following statements are correct about the reaction quotient, Q?

-Q expresses a particular ratio of products and reactants at any time during a reaction. -Q = K only at equilibrium. -The expression for Q is the same as the expression for K.

Which of the following starting mixtures would not be sufficient to establish chemical equilibrium for the following reaction? Choose all that apply.

-SO2 only -O2 only

Which of the following options correctly reflect the equation relating KP and Kc for a given reaction? Select all that apply.

-T is the temperature in kelvin. -R = 0.0821 atm⋅L/mol⋅K -Δngas is determined from the coefficients of the balanced equation.

Choose all the statements that correctly describe equilibrium expressions for reactions containing only gases.

-The equilibrium expression can be written in terms of the concentration of each gas in the reaction. -The equilibrium expression can be written in terms of the partial pressure of each gas in the reaction.

Which of the following statements correctly describe the rate equations for a system at equilibrium? Select all that apply.

-The rate of the forward reaction is equal to the rate of the reverse reaction. -The ratio [products]/[reactants]remains constant although reactions continue to occur.

Which of the following statements correctly describe a chemical system at equilibrium? Select all that apply.

-There appears to be no visible change in the concentrations of reactants or products. -The forward and reverse reactions occur at equal rates.

Which of the following statements about equilibrium expressions and equilibrium constants are correct? Choose all that apply.

-When a chemical reaction is multiplied by a constant, the corresponding equilibrium expression is raised to the power of that constant. -A homogeneous equilibrium is one where all reactants and products are in the same physical state. -The equilibrium expression for a reaction involving only gases can be written in terms of either partial pressures or concentrations.

The equilibrium constant, K, for a system at equilibrium expresses a particular ratio of equilibrium ______ of products and reactants at a particular _______.

-concentration -temperature

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.

-concentrations -pressures

At a given temperature, the rate constants for the forward and reverse reaction remain ______ and the ratio kf/kr is equal to the ______ constant for the reaction.

-constant -equilibrium

Changing the way an equilibrium reaction is written will also change the equilibrium ______ and the equilibrium _____ for that reaction.

-expression -constant

Match the magnitude of the equilibrium constant, KC, with the correct description of the reaction system. -Kc< -1* -Kc>

-favors reactants -both -favors products

When constructing an equilibrium expression, which of the following states are not included?

-liquids -solids

Match each of the following to the correct description. -reversible physical process -reversible chemical process -irreversible physical process

-melting -CH4 -Condensation -3H2

To construct the expression for the equilibrium constant Kc for a given reaction, the _______ concentrations are placed in the numerator and the ______ concentrations are placed in the denominator. Each term is then raised to the power of its stoichiometric coefficient from the _____ equation.

-product -reactant -balanced

Which of the following types of reactants and products do not appear in an equilibrium expression?

-pure liquids -pure solids

The concentrations of pure ____ and ____ are not included in the equilibrium expression for a given reaction.

-solids -liquids

Chemical equilibrium can be reached by starting with which of the following? Choose all that apply.

-some of each reactant -a mixture of reactants and products -some of each product

Which of the following options correctly reflect the steps required to calculate Kc at 1000 K? Select all that apply.

-Δngas = -1 -Kc = (3.9 x 10-2)(0.0821 x 1000)1 = 3.2

Which of the following options correctly reflect the equation relating KP and Kc for a given reaction? Select all that apply.

-Δngas is determined from the coefficients of the balanced equation. -R = 0.0821 atm⋅L/mol⋅K -T is the temperature in kelvin.

Given the following data, what is the value of KP for the reaction at 545 K?

0.0144

calculate the value of Kc for the reaction at this temperature.

0.17

Calculate the equilibrium concentration of PCl3 for the equilibrium system represented below.

0.49 M

Consider the equilibrium system 2NO2(g) ⇄ 2NO(g) + O2(g); KC1 = 1.1 x 10-5. What is the value of KC for the reaction 6NO2(g) ⇄ 6NO(g) + 3O2(g)?

1.1

What is the value of KC for 2B(g) ⇄ C(g) + D(g)?

2.5 x 1010

Which of the following reactions will have the equilibrium constant expression KC =

3A(aq) + 2B(s) ⇄ 2C(aq) 3A(g) + 2B(s) ⇄ 2C(aq) 3A(g) ⇄ 2B(s) + 2C(aq)

Given the following data: 2NO2(g) ⇄ 2NO(g) + O2(g); KC = 1.1 x 10-5 2NO(g) ⇄ N2(g) + O2(g); KC = 4.4 x 1018 what is the value of KC for the overall reaction 2NO2(g) ⇄ N2(g) + 2O2(g)?

4.8

Consider the equilibrium system 4A(g) + 2B(g) ⇄ 4C(g); KC1=47. What is the value of KC for the reaction 2A(g) + B(g) ⇄ 2C(g)?

6.9

Which of the following statements correctly describes a system at equilibrium for which KC = 1.2?

Both products and reactants are present in significant amounts at equilibrium.

Why are pure liquids and solids not included in the equilibrium constant expression for a given reaction?

The concentrations of pure solids and liquids do not change appreciably as the reaction approaches equilibrium.

If the equilibrium constant, KC, for a particular reaction is 1.22 x 1014, which of the following statements correctly describes the reaction?

There are large concentrations of products compared to reactants.

At equilibrium, the rate of the forward reaction is ______ to/than the rate of the reverse reaction.

equal

A system in which the rate of the forward reaction is equal to the rate of the reverse reaction is in a state of chemical ________.

equilibrium

True or false: The units for Q and K are mol/L.

false

The value of the equilibrium constant, KC, is a measure of how far the reaction proceeds toward the products at a given temperature. A small value of KC indicates that the reaction favors the ______, whereas a large value of KC indicates that the ______ will be present in a higher proportion.

reactants, products

A physical or chemical process that can occur in both the forward and the reverse direction is called a ______.

reversible process

The value of KP for a given reaction is the equilibrium constant based on _____.

the partial pressures of the reactants and products