WorksheetsCHEMICAL EQUILIBRIUM
Total questions: 37
Worksheet time: 45mins
Which of the following best describes a reversible chemical reaction?
A reaction that proceeds in only one direction
A reaction where the concentrations of reactants and products remain constant
A reaction that involves different substances as reactants and products
A reaction that occurs at a constant temperature
At the start of a reversible process, the reaction proceeds towards the formation of:
Reactants
Products
Equilibrium
Catalysts
What is the condition required for chemical equilibrium to be achieved?
The concentrations of reactants and products must be equal
The forward reaction rate must be faster than the reverse reaction rate
The rates of the forward and reverse reactions must be equal
The temperature must be constant throughout the reaction
Chemical equilibrium can be compared to the movement of skiers at a busy ski resort because:
The number of skiers carried up the mountain is equal to the number coming down the slopes
The number of people at the top and the number at the bottom of the slope do not change
Skiers undergo physical processes similar to the changes in chemical equilibrium
The concentration of skiers at the top and the bottom of the slope remains constant
How can the progress of the reaction N2O4(g) ⇌ 2NO2(g) be monitored?
By measuring the temperature change
By observing the color change
By measuring the pressure change
By analyzing the pH of the solution
Which of the following best describes the reaction N2O4 ⇌ 2NO2?
Irreversible reaction
Exothermic reaction
Endothermic reaction
Reversible reaction
What is the significance of the double arrow in the reaction equation N2O4 ⇌ 2NO2?
It indicates an irreversible reaction
It represents a catalyst in the reaction
It shows the direction in which the reaction proceed
It signifies that the reaction is reversible
How can chemical equilibrium be disturbed?
By changing the temperature of the system
By altering the pressure of the system
By adding or removing reactants or products
By increasing the surface area of the reaction vessel
What happens to the concentrations of N2O4 and NO2 at equilibrium in the reaction N2O4 ⇌ 2NO2?
Both concentrations increase
Both concentrations decrease
The concentration of N2O4 increases, while the concentration of NO2 decreases
The concentrations of N2O4 and NO2 remain constant
What is the general form of the equilibrium constant expression for a reaction with stoichiometric coefficients aA + bB ⇌ cC + dD?
K = [C]c[D]d/[A]a[B]b
K = [A]a[B]b/[C]c[D]d
K = [C]c[D]d + [A]a[B]b
K = [A]a[B]b - [C]c[D]d
What is the law of mass action?
The law stating that equilibrium constants remain constant with changing concentrations
The law stating that the rate of a chemical reaction is directly proportional to the concentration of reactants
The law stating that the volume of a gas is inversely proportional to its pressure
The law stating that energy is conserved in a chemical reaction
How is the equilibrium constant defined?
It is defined as the sum of the concentrations of reactants and products at equilibrium
It is defined as the ratio of the initial concentrations of reactants and products
It is defined as the ratio of the equilibrium concentrations of products to reactants
It is defined as the difference between the initial and equilibrium concentrations of reactants and products
Can the value of the equilibrium constant (K) change with temperature?
Yes, the value of K is temperature-dependent
No, the value of K remains constant regardless of temperature
Only for exothermic reactions
Only for endothermic reactions
How can the equilibrium constant (K) be used to predict the direction of a reaction?
If K is greater than 1, the reaction will proceed to the right (towards products)
If K is greater than 1, the reaction will proceed to the left (towards reactants)
If K is less than 1, the reaction will proceed to the right (towards products)
If K is less than 1, the reaction will proceed to the left (towards reactants)
Why is the equilibrium constant expressed using the concentrations of reactants and products rather than their amounts in moles?
Concentrations allow for easier comparison between different reactions
Concentrations are more precise than moles in measuring the extent of a reaction
Concentrations take into account the volume of the reaction vessel
Concentrations are directly related to the rate of the reaction
What is the key characteristic of a reversible reaction at equilibrium?
The conversion of reactants into products only
The conversion of products into reactants only
The forward and reverse reactions occurring simultaneously
The absence of any reaction occurring
Calculate the equilibrium constant (Kc) for the given reaction
N2 (g) + 3H2 (g) ↔ 2NH3 (g)
At equilibrium [N2] = 0.34 M, [H2] = 0.13 M, and [NH3] = 0.19 M.
48
33
48.0
33.07
Calculate the equilibrium constant (Kc) for the given reaction and tell whether equilibrium lies to the left or the right.
2NO (g) + Br2 (g) ↔ 2NOBr (g)
At equilibrium [NO] = 0.5 M, [Br2] = 0.25 M, and [NOBr] = 3.5 M.
56 lies to the right
200 lies to the right
196 lies to the left
56 lies to the left
The equilibrium constant (Kc) for the formation of nitrosyl chloride, an orange-yellow compound, from nitric oxide and molecular chlorine is 6.5 x 10 4 at 35 ⁰ C. In a certain experiment, 2.0 x 10 -2 mole of NO, 8.3 x10 -3 mole of Cl2, and 6.8 moles of NOCL are mixed in a 2.0-L flask.
2NO(g) + Cl2 ↔ 2NOCl (g)
Find Q and predict how the reaction will proceed.
2.9 x 10 7 to the left
3.0 x 10 7 to the left
2.89 x 10 7 to the right
2.89 x 10 5 to the left
Consider the following system at equilibrium:
CH4(g) + 2H2O (g) ↔ CO2 (g) + 4H2O (g)
Suppose the concentration of CH4 decreased, in which direction does the reaction shift to reestablish equilibrium?
The reaction shifts to the left
The reaction shifts to the right
Consider the following system at equilibrium:
CH4(g) + 2H2O (g) ↔ CO2 (g) + 4H2 (g)
Suppose the concentration of CH4 decreased, what happens to the concentrations of H2O, CO2, and H2 as the reaction shifts to reestablish equilibrium?
The concentrations of the products, CO2, and H2 will decrease and the reactant H2O, will increase in concentration.
The concentrations of the products, CO2, and H2 will increase and the reactant H2O, will decrease in concentration.
Predict whether the reaction will shift to the right, left or not be affected by an INCREASE in temperature
2H2O2 (g) ↔ 2H2O (g) + O2 (g) exothermic
left
right
no effect
Predict whether the reaction will shift to the right, left or not be affected by an INCREASE in temperature
2H2O2 (g) ↔ 2H2O (g) + O2 (g) endothermic
left
right
no effect
What is the Kc expression for this reaction? 2 NO(g) + O2(g) ⇌ 2 NO2(g)
Kc = [NO2]2 / [NO]2 [O2]
Kc = [NO]2 [O2] / [NO2]2
Kc = [NO]2 [O2] [NO2]2
Kc = [NO2]2 / [NO]2 + [O2]
What is the equilibrium expression for: Fe3O4(s) + 4H2(g) <=> 3Fe(s) + 4H2O(g) Kc =
[Fe]3 [H2O]4 / [Fe3O4] [H2]4
[Fe3O4] [H2]4 / [Fe]3 [H2O]4
[H2O]4 / [H2]4
[Fe] [H2O] / [Fe3O4] [H2]
If the equilibrium constant is much less than one (K << 1) then
Equilibrium is not established.
Equilibrium lies to the right (products are favored)
Equilibrium lies to the left (reactants are favored)
Neither products or reactants are favored.
Which of the following is TRUE when the reaction proceeds toward equilibrium in the reverse direction?
reactant concentrations increases
product concentration increases
reaction quotient consequently increases
denominator of Qc decreases
What does a large K at equilibrium indicate?
very little reactant has been converted
It indicates how rapidly or slowly equilibrium will be reached
most of the reactant has been converted to product
All of the above
What is the value of K when equilibrium favors the products and equilibrium lies to the right?
>1
<1
1
0
For the reaction
4NH3(g) + 7O2(g) ⇌ 4NO2(g) + 6H2O(g)
What is the equilibrium shift if more O2 is added?
forward
backward
No shift
What is the Keq expression for this reaction?
2 NO(g) + O2(g) ⇌ 2 NO2(g)
Keq = [NO2]2 / [NO]2 [O2]
Keq = [NO]2 [O2] / [NO2]2
Keq = [NO]2 [O2] [NO2]2
Keq = [NO2]2 / [NO]2 + [O2]
For the reaction, choose the CORRECT equilibrium constant, Kc.
What is the equilibrium constant expression?
2SO3(g) ↔ 2SO2(g) + O2(g)
Kc = 4.08x10-3 at 1000K
What is Kp?
2NOBr(g) + Cl2(g) ↔ 2NO(g) + 2BrCl(g)
if
2NOBr(g) ↔ 2NO(g) + Br2(g)
has a Kc = 0.014
Br2(g) + Cl2(g) ↔ 2BrCl(g)
has a Kc = 7.2
Given that the Kp for the following reaction is 4.20 at 500 K, what is the Kc?
N2(g) + 3 H2(g) ⇌ 2 NH3(g)
Kp =Kc(RT)Δn
594
7070
116
41.0
5120
