Ch 17 pt 1 Smartbook

Given the balanced equation 2PbO (s) + O2 (g) ⇌ 2PbO2 (s), calculate the value of Δngas. Multiple choice question.

-1

The law of mass action states that _____. Select all the options that complete the sentence correctly. Multiple select question.

-Equilibrium can be reached from any direction i.e, by beginning with a mixture of reactants or products, or both. -A chemical system reaches a state where the concentration of reactants and products is a constant ratio.

Which of the following options correctly describe the equilibrium constant K? Select all that apply. Multiple select question.

-K expresses a particular ratio of equilibrium concentrations of products and reactants. -K = kfwd / krev for a system at equilibrium. -The value of K is characteristic of a particular equilibrium system.

Which of the following statements about the reaction quotient Q are correct? Select all that apply.

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

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

-The forward and reverse reactions occur at equal rates. -There is no longer a change in concentration of reactants and products over time.

Consider the equilibrium system 2NO2 (g) ⇌ 2NO (g) + O2 (g); K1 = 1.1 x 10-5. What is the value of K for the reaction 6NO2 (g) ⇌ 6NO (g) + 3O2 (g)? Multiple choice question.

1.3 x 10^-15

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

1/[02]

For the reaction H2C2O4 (aq) ⇌ 2H+ (aq) + C2O42- (aq), Kc = 3.8 × 10-6. Calculate the value of Kc for the reaction 5H2C2O4 (aq) ⇌ 10H+ (aq) + 5C2O42- (aq). Multiple choice question.

7.9 × 10^-28

Given the reaction 2NO2 (g) ⇌ 2NO (g) + O2 (g); K = 1.1 x 10-5, what is the value of K for the reaction 2NO (g) + O2 (g) ⇌ 2NO2 (g)? Multiple choice question.

9.1 x 10^4

intermediate K

Both reactants and products will be present in significant amounts at equilibrium

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

Which of the following reactants and/or products would not appear in the expression for Q or K for the following reaction? Select all that apply. 4HCl (aq) + MnO2 (s) ⇌ MnCl2 (aq) + 2H2O (l) + Cl2 (g) Multiple select question.

H2O, MnO2

Given the following reaction, which concentration terms appear in the denominator of the expressions for Qc and Kc? Select all that apply. CFCl3 (g) + HCl (g) ⇌ CCl4 (g) + HF (g)

HCl, CFCl3

Which of the following options correctly describes the units of K for a reaction? Multiple choice question.

K is usually quoted without units

Select the new equilibrium constant, K', of a reaction multiplied by a factor n, that is n(aA + bB ⇌ cC + dD). Multiple choice question.

K' = K^n

How does the equilibrium constant change when all the coefficients of a balanced equation are multiplied by the same factor?

K' = K^n, where n is the factor by which the coefficients are multiplied.

Select the correct expression for the equilibrium constant of an overall reaction consisting of four reaction steps. Multiple choice question.

Koverall = K1 x K2 x K3 x K4

Which of the following symbols for Q denote the reaction quotient based on molar concentrations? Multiple choice question.

Qc

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

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

Why are the values of Q and K unitless? Multiple choice question.

The units of concentration are activities, which are the ratio of concentration of a substance to its standard-state concentration.

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

Given the balanced equation 2NO2 (g) ⇌ 2NO (g) + O2 (g), what is the expression for K for the reverse reaction?

[NO2]2 / [NO]2[O2]

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

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

The subscript "c" used in the symbols Qc and Kc indicate that these quantitates are based on the ______ of products and reactants.

concentrations

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

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

if the value of K for the forward reaction is less than 1, the value of K for the reverse reaction is _____ than 1. Multiple choice question.

greater

As a reaction proceeds, the value of Q _____. Multiple choice question.

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

As a reaction proceeds toward equilibrium from reactants to products (i.e., from left to right as written), the value of Q is _____. Multiple choice question.

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

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

In heterogeneous reactions, ______ are not included in the Q or K expressions because their concentrations are constant and do not change as the reaction approaches equilibrium. Multiple choice question.

pure liquids or soilds

For a balanced chemical equation that has been multiplied by some factor x, the corresponding reaction quotient (or equilibrium constant) must be ______ that same factor.

raised to the power of

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

reactant, products

When Q < K, the reaction will proceed so that the concentrations of the _____ decrease and the concentrations of the _____ increase. Multiple choice question.

reactants, products

The concentrations of pure _______ and _______ are not included in the expression for Q or K for a given heterogeneous reaction.

solids, liquids

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

the partial pressures of the reactants and products

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

the reciprocal of

Match each of the following equations to the correct value for Δngas

Δngas = 0 -> H2(g) + I2(g) ⇌ 2HI (g) Δngas = -1 -> 3O2 (g) ⇌ 2O3 (g) Δngas = 1 -> CO2 (s) ⇌ CO2 (g)