Deck 13: Reaction Rates Equilibrium

Question 1

In the diagram, the number 1 corresponds to the:

A) reactants.
B) products.
C) activation energy.
D) transition state.
E) net energy change.

Answer 1

net energy change.

Question 2

In the diagram, the activation energy of the FORWARD reaction is about:

A) 60 kJ.
B) 130 kJ.
C) 80 kJ.
D) 20 kJ.

Answer 2

80 kJ.

Question 3

In the diagram, the forward reaction will probably not proceed without an input of energy because the:

A) activation energy is too high.
B) net energy change is too low.
C) products are too far apart from the reactants.
D) reactant energy is too high to start with.

Answer 3

activation energy is too high.

Question 4

In the diagram, the number 3 corresponds to the:

A) reactants.
B) products.
C) activation energy.
D) transition state.
E) net energy change.

Question 5

Which factor tends to increase the rate of a reaction?

A) Decreasing the temperature
B) Decreasing the concentration of the reactants
C) Increasing the concentration of the reactants
D) Increasing the activation energy of the reaction

Question 6

In the diagram, the energy of the transition state is about:

A) 50 kJ/mol.
B) 130 kJ/mol.
C) 80 kJ/mol.
D) 20 kJ/mol.

Question 7

In the diagram, how do the concentrations of the reactants and products compare at equilibrium as a general rule?

A) They are equal.
B) The reactant concentration is greater than that of the product.
C) The product concentration is greater than that of the reactant.

Question 8

Chemical reactions occur when molecules, atoms, or ions collide. However, not every collision results in a reaction. In order for a reaction to occur,

A) the molecules must be big enough.
B) the energy of the molecules is not important, but the molecules must collide at the correct orientation.
C) the molecules must have enough kinetic energy and collide at the correct orientation.
D) the molecules must be moving slowly enough to interact, and must be rotating in opposite directions.

Question 9

In the diagram, the FORWARD reaction is:

A) endothermic.
B) exothermic.
C) exergetic.
D) ergonomic.

Question 10

Which statement correctly describes reaction rates?

A) Decreasing the reactant concentration will increase reaction rate because, if there are fewer particles, there is more room to collide.
B) Decreasing the temperature will increase reaction rate because, if the particles are moving faster, there will be fewer collisions.
C) Both decreasing the reactant concentration and decreasing the temperature will increase reaction rate.
D) Neither decreasing the reactant concentration nor decreasing the temperature will increase reaction rate.

Question 11

In the diagram, the net energy change is about:

A) 60 kJ.
B) 130 kJ.
C) 80 kJ.
D) 20 kJ.

Question 12

In the diagram, the reaction described is _____ and the equilibrium favors the _____.

A) endothermic; reactants
B) endothermic; products
C) exothermic; reactants
D) exothermic; products

Question 13

In the diagram, the number 2 corresponds to the:

A) reactants.
B) products.
C) activation energy.
D) transition state.
E) net energy change.

Question 14

In the diagram, the number 5 corresponds to the:

A) reactants.
B) products.
C) activation energy.
D) transition state.
E) net energy change.

Question 15

In the diagram, the activation energy of the REVERSE reaction is about:

A) 50 kJ.
B) 130 kJ.
C) 80 kJ.
D) 60 kJ.

Question 16

Which statement correctly describes reaction rates?

A) Decreasing the reactant concentration will decrease reaction rate because, if there are fewer particles, there will be fewer collisions.
B) Increasing the temperature will decrease reaction rate because, if the particles are moving faster, there will be fewer collisions.
C) Both decreasing the reactant concentration and increasing the temperature will decrease reaction rate.
D) Neither decreasing the reactant concentration nor increasing the temperature will decrease reaction rate.

Question 17

Which factor does NOT affect the rate of a reaction?

A) Temperature
B) Concentration
C) Activation energy
D) Formula mass

Question 18

In the diagram, the number 4 corresponds to the:

A) reactants.
B) products.
C) activation energy.
D) transition state.
E) net energy change.

Question 19

Which factor tends to increase rate of a reaction?

A) Increasing the temperature
B) Decreasing the concentration of the reactants
C) Increasing the concentration of the products
D) The presence of a noble gas

Question 20

When a chemical reaction is at equilibrium, which statement is TRUE, by definition?

A) The concentrations of the reactants and of the products are equal.
B) The rate of the forward reaction is equal to the rate of the reverse reaction.
C) All reactants have been converted to products.
D) Both the forward and reverse reactions cease.

Question 21

Given the following equation and equilibrium concentrations, determine the value of the equilibrium constant.
PCl₅ (g) $\leftrightarrow$ PCl₃ (g) + Cl₂ (g)
[PCl₅] = 5.30 M; [PCl₃] = 0.406 M; [Cl₂] = 0.406 M

A) 32.2
B) 0.0311
C) 6.52
D) 0.153

Question 22

The equilibrium expression of the following reaction is represented by:
2 CO₂ (g) $\leftrightarrow$ 2 CO (g) + O₂ (g)

A)
B)
C)
D)

Question 23

The symbol used to represent the equilibrium solubility of a slightly soluble compound in water is:

A) K_a.
B) K_b.
C) K_s.
D) K_sp.

Question 24

Cyanic acid, HOCN, ionizes in water to produce the hydronium ion, H₃O⁺, and the cyanate ion, OCN^-: HOCN (aq) + H₂O (l) $\leftrightarrow$ H₃O⁺ (aq) + OCN^- (aq) K = 3.5 × 10^-4
If [H₃O⁺] = 7.3 × 10^-4 M and [OCN^-] = 7.3 × 10^-4 M, what is the value of the acid concentration, [HOCN]?

A) 1.5 × 10^-3 M
B) 660 M
C) 0.48 M
D) 2.1 M

Question 25

In a saturated solution of cobalt(II) carbonate, CoCO₃, both [Co²⁺] and [CO₃^2-] = 3.7 × 10^-7 M. Calculate the value of the solubility product for this compound.

A) 1.4 × 10^-13
B) 6.1 × 10^-4
C) 7.4 × 10^-7
D) 1.9 × 10^-7

Question 26

Given the following equation and equilibrium concentrations, determine the value of the equilibrium constant.
2 NO₂ $\leftrightarrow$ N₂O₄ (g)
[NO₂] = 0.579 M; [N₂O₄] = 0.234 M

A) 0.698
B) 1.43
C) 0.404
D) 2.47

Question 27

Write the solubility product expression for the following solubility equilibrium: BaSO₄ (s) $\leftrightarrow$ Ba²⁺ (aq) + SO₄^2- (aq)

A)
B)
C)
D)

Question 28

Which of the following K values indicates a reaction that most favors the reactants?

A) 1 × 10^-2
B) 1 × 10²
C) 1 × 10^-11
D) 1 × 10¹¹

Question 29

According to Le Châtelier's principle:

A) equilibrium cannot be established without a change in temperature or pressure.
B) equilibrium will be established quickly if there is no disturbance in temperature or pressure.
C) when a disturbance occurs to a system at equilibrium, a new equilibrium constant will be established.
D) when a disturbance occurs to a system at equilibrium, the system will shift to minimize the disturbance.

Question 30

Consider the equilibrium reaction between the gas phases of hydrogen and bromine: H₂ (g) + Br₂ (g) $\rightarrow$ 2 HBr (g)
If the partial pressures of hydrogen and of bromine are 0.016 atm each, what is the partial pressure of HBr if K = 2.2 × 10³?

A) 0.75 atm
B) 0.56 atm
C) 8.6 × 10⁶ atm
D) 2.9 × 10³ atm

Question 31

In a saturated solution of aluminum phosphate, AlPO₄, both [Al³⁺] and [PO₄^3-] = 7.9 × 10^-10 M. Calculate the value of the solubility product for this compound.

A) 6.2 × 10^-19
B) 2.8 × 10^-5
C) 1.6 × 10^-9
D) 4.0 × 10^-10

Question 32

Which K value indicates a reaction that MOST favors the products?

A) 1 × 10^-2
B) 1 × 10²
C) 1 × 10^-11
D) 1 × 10¹¹

Question 33

The equilibrium expression of the following reaction is represented by:
2 CO (g) + O₂ (g) $\leftrightarrow$ 2 CO₂ (g)

A)
B)
C)
D)

Question 34

Considering the solubility product values for the following carbonates, which is the MOST soluble?

A) CuCO₃K_sp = 1.4 × 10^-10
B) FeCO₃ K_sp = 3.2 × 10^-11
C) PbCO₃K_sp = 7.4 × 10^-14
D) MgCO₃K_sp = 3.5 × 10^-8

Question 35

Write the solubility product expression for the following solubility equilibrium: CuOH (s) $\leftrightarrow$ Cu⁺ (aq) + OH^- (aq)

A)
B)
C)
D)

Question 36

Consider the equilibrium reaction between the gas phases of hydrogen and iodine: H₂ (g) + I₂ (g) $\leftrightarrow$ 2 HI (g)
If the partial pressures of hydrogen and of iodine are 0.42 atm each, what is the partial pressure of HI if K = 7.1 × 10²?

A) 11 atm
B) 63 atm
C) 125 atm
D) 2.5 × 10^-4 atm

Question 37

Considering the solubility product values for the following carbonates, which is the LEAST soluble?

A) CuCO₃K_sp = 1.4 × 10^-10
B) FeCO₃ K_sp = 3.2 × 10^-11
C) PbCO₃K_sp = 7.4 × 10^-14
D) MgCO₃K_sp = 3.5 × 10^-8

Question 38

The equilibrium expression of the following reaction is represented by:
H₂ (g) + I₂ (g) $\leftrightarrow$ 2 HI (g)

A)
B)
C)
D)

Question 39

If an acetic acid, HC₂H₃O₂, buffer solution contains [HC₂H₃O₂] = 0.12 M and [C₂H₃O₂^-] = 0.15 M, what is the [H₃O⁺] in the solution? HC₂H₃O₂ (aq) + H₂O (l) $\leftrightarrow$ H₃O⁺ (aq) + C₂H₃O₂^- (aq) K = 1.8 × 10^-5

A) 1.4 × 10^-5 M
B) 2.3 × 10^-5 M
C) 1.0 × 10^-3 M
D) 3.2 × 10^-5 M

Question 40

Which choice is NOT included in the equilibrium expression?

A) solids
B) gases
C) aqueous solutions