Unit 5 - Chemical Equilibrium

Question 1

T/F
Most chemical reactions are irreversible. Only few reactions proceed to completion.

Answer 1

F

Question 2

It exists when two opposing reactions occur simultaneously at the same rate.

Answer 2

Chemical equlibrium

Question 3

It is a dynamic process.

Answer 3

Chemical equilibrium

Question 4

T/F
Once equilibrium is achieved, the amount of each reactant and product remains constant.

Answer 4

T

Question 5

T/F
As a system approaches equilibrium, both the forward and reverse reactions are occuring.

Answer 5

T

Question 6

All reactants and products are in same phase and cannot be separated.

Answer 6

Homogenous equilibrium

Question 7

Reactants and products are not in homogenous phase and can be separated.

Answer 7

Heterogenous equilibrium

Question 8

T/F
The forward rate will be the reactant side.

Answer 8

T

Question 9

T/F
The reverse rate will be the product side.

Answer 9

T

Question 10

States that the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation.

Answer 10

Law of mass action

Question 11

It relates the concentrations of reactants and products at equilibrium.

Answer 11

Equilibrium constant

Question 12

T/F
It is the product of the concentrations of PRODUCTS of a chemical equilibrium divided by the concentrations of REACTANTS, each raised to the power equal to its coefficient in the balanced chemical equation.

Answer 12

T

Question 13

T/F
In writing equilibrium constant expression, a pure solid or a pure liquid in the reaction is omitted from the expression.

Answer 13

T

Question 14

T/F
The concentration of a pure solid or a pure liquid is always the same.

Answer 14

T

Question 15

The activity of liquid or solid is defined as _____.

Answer 15

1

Question 16

T/F
H2O(l) has activity of 1 while H2O(g) is considered in the expression.

Answer 16

T

Question 17

This results from a reversible reaction involving reactants and products that are in different phases.

Answer 17

Heterogeneous equilibrium

Question 18

T/F
In heterogeneous equilibrium, neither density nor molar mass is a variable, the concentrations of solids and pure liquids are constant.

Answer 18

T

Question 19

T/F
The concentrations of pure liquids and pure solids are not included in equilibrium constant expressions.

Answer 19

T

Question 20

The larger K the more _____ are present at equilibrium.

A. Reactants
B. Products

Answer 20

B

Question 21

The smaller K the more _____ are present at equilibrium.

A. Reactants
B. Products

Answer 21

A

Question 22

If K > 1, then products dominate at equilibrium and equilibrium lies to the _____.

A. Left
B. Right

Answer 22

B

Question 23

If K < 1, then products dominate at equilibrium and equilibrium lies to the _____.

A. Left
B. Right

Answer 23

A

Question 24

If K > 1, the reaction is _____.

A. Product-favored; product predominates at equilibrium.
B. Reactant-favored; reactant predominates at equilibrium

Answer 24

A

Question 25

If K < 1, the reaction is _____. A. Product-favored; product predominates at equilibrium. B. Reactant-favored; reactant predominates at equilibrium

Answer 25

B

Question 26

T/F In the magnitude of equilibrium constants, an equilibrium can be approached from any direction.

Answer 26

T

Question 27

The ___ for a reaction in one direction is the reciprocal of the equilibrium constant of the reaction in the opposite direction.

Answer 27

Kc

Question 28

It is the equilibrium constant for a net reaction made up of two or more steps is the product of the equilibrium constants for the individual steps.

Answer 28

Multiple equilibria

Question 29

T/F In predicting the direction of the reaction, the reaction quotient, Q, for a reaction at conditions NOT at equilibrium.

Answer 29

T

Question 30

T/F Q = K only at equilibrium.

Answer 30

T

Question 31

If K = Q the _____. A. System is at equilibrium. B. Forward reaction is favored. C. Reverse reaction is favored.

Answer 31

A

Question 32

If K > Q the _____. A. System is at equilibrium. B. Forward reaction is favored. C. Reverse reaction is favored.

Answer 32

B

Question 33

If K < Q the _____. A. System is at equilibrium. B. Forward reaction is favored. C. Reverse reaction is favored.

Answer 33

C

Question 34

T/F Changes in experimental conditions may disturb the balance and shift the equilibrium.

Answer 34

T

Question 35

Factors that affect equilibrium.

Answer 35

Concentration Catalyst Temperature Volume and Pressure

Question 36

A principle wherein if stress is applied to a system that is in equilibrium, the system will adjust in such a way that the stress is partially offset as the system reaches a new equilibrium position.

Answer 36

Le Chatelier's Principle

Question 37

A + B ⇋ C + D Increasing the amount of A or B. A. Forward B. Reverse C. No shift

Answer 37

A

Question 38

A + B ⇋ C + D Increasing the amount of C or D. A. Forward B. Reverse C. No shift

Answer 38

B

Question 39

A + B ⇋ C + D Decreasing the amount of A or B. A. Forward B. Reverse C. No shift

Answer 39

B

Question 40

A + B ⇋ C + D Decreasing the amount of C or D. A. Forward B. Reverse C. No shift

Answer 40

A

Question 41

A + B ⇋ C + D Reacting A with compound E. A. Forward B. Reverse C. No shift

Answer 41

B

Question 42

A + B ⇋ C + D Removing C as the reaction proceeds. A. Forward B. Reverse C. No shift

Answer 42

A

Question 43

A system that RELEASES heat to the surroundings, has a negative ΔH (-ΔH) by convention, because the enthalpy of the products is LOWER than the enthalpy of the reactants of the system.

Answer 43

Exothermic reaction

Question 44

A system of reactants that ABSORBS heat from the surroundings in a reaction has a positive ΔH (+ ΔH), because the HIGHER of the products is HIGHER than the enthalpy of the reactants of the system.

Answer 44

Endothermic reaction

Question 45

Changes in volume and pressure affect only systems involving _____. A. Solid B. Liquid C. Gases

Answer 45

C

Question 46

T/F Changes in volume and pressure increase in pressure or decrease in volume favors the reaction where there is less total number of moles of gases.

Answer 46

T

Question 47

T/F Changes in volume and pressure decrease in pressure or increase in volume favors the reaction where there is higher total number of moles of gases.

Answer 47

T

Question 48

T/F Presence of catalyst does not affect the state of equilibrium.

Answer 48

T

Question 49

T/F Presence of catalyst allows the system to reach equilibrium faster.

Answer 49

T