Question 1

Which of the following is true regarding the effect of a catalyst on chemical equilibrium?

Accepted Answer

A catalyst increases the rate of both the forward and reverse reactions, but it does not change the position of equilibrium. Therefore, the quantity of products remains unchanged.

Question 2

The sulfide ion, S²^-, reacts with water as a weak base: S²^- + H₂O SH^- + OH^-K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH^-?

Accepted Answer

The reaction between sulfide ion and water can be written as:

SS1U1P12S1S1P0S1U1P1-S1S1P0 + HS1U1B12S1U1B0O → SHS1U1P1-S1S1P0 + OHS1U1P1-S1S1P0S1U1P1

Let x be the concentration of OHS1U1P1-S1S1P0 produced. Then initially the concentration of SS1U1P12S1S1P0S1U1P1-S1S1P0 is 0.50 M. Because of the 1:1 stoichiometry between SS1U1P12S1S1P0S1U1P1-S1S1P0 and OHS1U1P1-S1S1P0, the concentration of the sulfide ion will decrease by x M. And because water is present in excess, the concentration of the HS1U1B12S1U1B0O does not change significantly, so its concentration can be considered to be 0.50 M throughout the reaction.

Using the equilibrium constant expression:

K = [SHS1U1P1-S1S1P0][OHS1U1P1-S1S1P0S1U1P1] / [SS1U1P12S1S1P0S1U1P1-S1S1P0][HS1U1B12S1U1B0O]

K = 1.0 (given)

Substituting the concentrations and solving for x:

1.0 = (x)(0.50) / (0.50 - x)

0.50 - x = x/1.0

1.5x = 0.50

x = 0.33 M

Therefore, the resulting concentration of OHS1U1P1-S1S1P0 is 0.33 M. The closest answer choice is B) 0.37 M, which is the best answer choice.

Question 3

Cylinders of NO gas may contain small quantities of oxygen as impurities, leading to the formation of NO₂ in equilibrium with the NO and oxygen. Is this contamination by NO₂ dependent on pressure in the tank?

Accepted Answer

According to Le Chatelier's principle, increasing the pressure will shift the equilibrium towards the side with fewer moles of gas. Since the formation of NO₂ from NO and O₂ results in fewer moles of gas, higher pressure will favor the formation of more NO₂.

Question 4

Which of the following relationships are sufficient to assure that reactants and products will be in their standard state at equilibrium?
(I) $\Delta$ G = 0
(II) $\Delta$ G° = 0
(III) K = 1

Accepted Answer

At equilibrium, the standard Gibbs free energy change (ΔG°) is zero, and the equilibrium constant (K) is 1, indicating that reactants and products are in their standard states.

Question 5

What happens to the equilibrium between NO₂(g) and N₂O₄(g) in inert argon when the volume is increased and additional argon is added to maintain a constant total pressure?

Accepted Answer

Increasing the volume shifts the equilibrium towards the side with more moles of gas, which is NO₂, increasing its ratio to N₂O₄. Adding inert argon does not affect the equilibrium position.

Question 6

The gas-phase equilibrium of the oxidation of sulfur dioxide, shown here, has an equilibrium constant, K_p, value of 4.17 *10² at 200$\degree$C. If a closed vessel was filled with sulfur trioxide and the initial pressure of SO₃ was 0.033 atm at 200$\degree$C, what would be the final partial pressure of SO₃? 2SO₂(g) + O₂(g) 2SO₃(g)

Accepted Answer

Since the equilibrium constant is greater than one, it means that the forward reaction is favored at equilibrium. Therefore, the concentration of sulfur trioxide will decrease and the concentration of sulfur dioxide and oxygen will increase until the equilibrium constant is reached. This implies that the final partial pressure of sulfur trioxide will be less than 0.033 atm.

Question 7

A student determined the equilibrium concentration in the following equation by neglecting the x term in the denominator. Was she justified or not in this approximation and why? K = 4.0 * 10^-² =

Accepted Answer

Neglecting the x term in the denominator is only justified if the value of x is much less than the initial concentration. In this case, we cannot determine this without calculating x or providing more information. Therefore, neglecting the x term significantly reduces the denominator, which is not acceptable.

Question 8

In the ICE table started for calculating equilibrium concentrations of the reaction shown, the terms in the "change" column are __________ M²⁺ + 4L ML₄⁺ [M²⁺] [L] [ML₄⁺] I 0.10 M 0.32 M 0 M C ______ ______ ______ E

Accepted Answer

The answer of In the ICE table started for calculating...

Question 9

In the equation relating equilibrium to thermodynamics, a = -RTb,

Accepted Answer

The answer of In the equation relating equilibrium to thermodynamics,...

Question 10

What is the difference between "$\Delta$G" and "$\Delta$G$\degree$"?

Accepted Answer

The symbols represent thermodynamic quantities: the first symbol without the "°" refers to Gibbs free energy change under any conditions, while the second symbol with the "°" refers to Gibbs free energy change for a reaction where all reactants and products are in their standard states.

Question 11

Which of the following must be true for a reaction to proceed to form products?

Accepted Answer

The answer of Which of the following must be true...

Question 12

If the temperature of an endothermic reaction at equilibrium could be increased instantaneously, what would be the instantaneous effect on Q and K before equilibrium was again achieved?

Accepted Answer

For an endothermic reaction, increasing the temperature shifts the equilibrium to favor the products, which increases the value of the equilibrium constant, K. The reaction quotient, Q, remains unchanged immediately after the temperature change because it reflects the ratio of concentrations at that moment, which have not yet adjusted to the new temperature.

Question 13

The reaction of bromine gas with chlorine gas, shown here, has a K_p value of 7.20. If a closed vessel was charged with the two reactants, each at an initial partial pressure of 0.500 atm, and the product also at 0.500 atm, what would be the equilibrium partial pressure of BrCl(g)? Br₂(g) + Cl₂(g) 2BrCl(g)

Accepted Answer

Using the equilibrium constant expression: K_p = [BrCl]2 / ([Br2][Cl2]) At equilibrium, let the partial pressure of BrCl be x atm. Then, the partial pressures of Br2 and Cl2 will each be (0.500 - x) atm. Substitute into the equilibrium constant expression: 7.20 = x2 / [(0.500 - x)2] Solve for x using algebra, and you will get x = 0.859 atm. Therefore, the equilibrium partial pressure of BrCl is 0.859 atm.

Question 14

In a simple equilibrium A + B  C, will there be any stress to the system if both B and C were added to the equilibrium system simultaneously and in the same amount?

Accepted Answer

The answer of In a simple equilibrium A + B...

Question 15

The reaction of bromine gas with chlorine gas, shown here, has a K_p value of 7.20. If a closed vessel was charged with the two reactants, each at an initial partial pressure of 0.500 atm, what would be the equilibrium partial pressure of BrCl(g)? Br₂(g) + Cl₂(g) 2BrCl(g)

Accepted Answer

The answer of The reaction of bromine gas with chlorine...

Question 16

A reaction X + 2Y$\rightarrow$ 3Z is started with 1.0 M Z and no X or Y. To calculate the equilibrium concentrations of all species using an ICE table, which of the following would you enter in the Z column for the C row?

Accepted Answer

The answer of A reaction X + 2Y$\rightarrow$ 3Z is...

Question 17

When can an x be ignored in solving an equilibrium expression derived from an ICE table?

Accepted Answer

When the value of x is very small compared to the initial concentration or other terms in the expression, it can be ignored as it will have a negligible impact on the final answer. This is because the value of x represents the change in concentration from the initial concentration, and if this change is very small, it can be ignored.

Question 18

Increasing the temperature of an exothermic reaction results in __________

Accepted Answer

According to Le Chatelier's principle, increasing the temperature of an exothermic reaction shifts the equilibrium to favor the reactants, resulting in more reactants and fewer products.

Question 19

Which of the following occurs when products are removed from a chemical reaction in solution or the gas phase at equilibrium?

Accepted Answer

When products are removed from a reaction at equilibrium, the reaction quotient Q decreases, causing the equilibrium to shift to the right to produce more products to re-establish equilibrium.

Question 20

To solve an equation of the form ax² + bx + c = 0 for values of x, use __________

Accepted Answer

The answer of To solve an equation of the form...

Quiz 16: Chemical Equilibrium

Which of the following is true regarding the effect of a catalyst on chemical equilibrium?

The sulfide ion, S²^-, reacts with water as a weak base: S²^- + H₂O SH^- + OH^-K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH^-?

Cylinders of NO gas may contain small quantities of oxygen as impurities, leading to the formation of NO₂ in equilibrium with the NO and oxygen. Is this contamination by NO₂ dependent on pressure in the tank?

Which of the following relationships are sufficient to assure that reactants and products will be in their standard state at equilibrium? (I) $\Delta$ G = 0 (II) $\Delta$ G° = 0 (III) K = 1

What happens to the equilibrium between NO₂(g) and N₂O₄(g) in inert argon when the volume is increased and additional argon is added to maintain a constant total pressure?

A student determined the equilibrium concentration in the following equation by neglecting the x term in the denominator. Was she justified or not in this approximation and why? K = 4.0 * 10^-² =

In the ICE table started for calculating equilibrium concentrations of the reaction shown, the terms in the "change" column are ____ M²⁺ + 4L ML₄⁺ [M²⁺] [L] [ML₄⁺] I 0.10 M 0.32 M 0 M C E

In the equation relating equilibrium to thermodynamics, a = -RTb,

What is the difference between " $\Delta$ G" and " $\Delta$ G $\degree$ "?

Which of the following must be true for a reaction to proceed to form products?

If the temperature of an endothermic reaction at equilibrium could be increased instantaneously, what would be the instantaneous effect on Q and K before equilibrium was again achieved?

In a simple equilibrium A + B C, will there be any stress to the system if both B and C were added to the equilibrium system simultaneously and in the same amount?

The reaction of bromine gas with chlorine gas, shown here, has a K_p value of 7.20. If a closed vessel was charged with the two reactants, each at an initial partial pressure of 0.500 atm, what would be the equilibrium partial pressure of BrCl(g) ? Br₂(g) + Cl₂(g) 2BrCl(g)

A reaction X + 2Y $\rightarrow$ 3Z is started with 1.0 M Z and no X or Y. To calculate the equilibrium concentrations of all species using an ICE table, which of the following would you enter in the Z column for the C row?

When can an x be ignored in solving an equilibrium expression derived from an ICE table?

Increasing the temperature of an exothermic reaction results in __________

Which of the following occurs when products are removed from a chemical reaction in solution or the gas phase at equilibrium?

To solve an equation of the form ax² + bx + c = 0 for values of x, use __________

Quiz 16: Chemical Equilibrium

Which of the following is true regarding the effect of a catalyst on chemical equilibrium?

The sulfide ion, S2-, reacts with water as a weak base: S2- + H2O SH- + OH- K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH-?

Cylinders of NO gas may contain small quantities of oxygen as impurities, leading to the formation of NO2 in equilibrium with the NO and oxygen. Is this contamination by NO2 dependent on pressure in the tank?

Which of the following relationships are sufficient to assure that reactants and products will be in their standard state at equilibrium? (I) Δ\DeltaΔ G = 0 (II) Δ\DeltaΔ G° = 0 (III) K = 1

What happens to the equilibrium between NO2(g) and N2O4(g) in inert argon when the volume is increased and additional argon is added to maintain a constant total pressure?

A student determined the equilibrium concentration in the following equation by neglecting the x term in the denominator. Was she justified or not in this approximation and why? K = 4.0 * 10-2 =

In the ICE table started for calculating equilibrium concentrations of the reaction shown, the terms in the "change" column are __________ M2+ + 4L ML4+ [M2+] [L] [ML4+] I 0.10 M 0.32 M 0 M C ______ ______ ______ E

In the equation relating equilibrium to thermodynamics, a = -RTb,

What is the difference between " Δ\DeltaΔ G" and " Δ\DeltaΔ G °\degree° "?

Which of the following must be true for a reaction to proceed to form products?

If the temperature of an endothermic reaction at equilibrium could be increased instantaneously, what would be the instantaneous effect on Q and K before equilibrium was again achieved?

In a simple equilibrium A + B C, will there be any stress to the system if both B and C were added to the equilibrium system simultaneously and in the same amount?

The reaction of bromine gas with chlorine gas, shown here, has a Kp value of 7.20. If a closed vessel was charged with the two reactants, each at an initial partial pressure of 0.500 atm, what would be the equilibrium partial pressure of BrCl(g) ? Br2(g) + Cl2(g) 2BrCl(g)

A reaction X + 2Y →\rightarrow→ 3Z is started with 1.0 M Z and no X or Y. To calculate the equilibrium concentrations of all species using an ICE table, which of the following would you enter in the Z column for the C row?

When can an x be ignored in solving an equilibrium expression derived from an ICE table?

Increasing the temperature of an exothermic reaction results in __________

Which of the following occurs when products are removed from a chemical reaction in solution or the gas phase at equilibrium?

To solve an equation of the form ax2 + bx + c = 0 for values of x, use __________

The sulfide ion, S²^-, reacts with water as a weak base: S²^- + H₂O SH^- + OH^-K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH^-?

Cylinders of NO gas may contain small quantities of oxygen as impurities, leading to the formation of NO₂ in equilibrium with the NO and oxygen. Is this contamination by NO₂ dependent on pressure in the tank?

Which of the following relationships are sufficient to assure that reactants and products will be in their standard state at equilibrium? (I) $\Delta$ G = 0 (II) $\Delta$ G° = 0 (III) K = 1

What happens to the equilibrium between NO₂(g) and N₂O₄(g) in inert argon when the volume is increased and additional argon is added to maintain a constant total pressure?

A student determined the equilibrium concentration in the following equation by neglecting the x term in the denominator. Was she justified or not in this approximation and why? K = 4.0 * 10^-² =

In the ICE table started for calculating equilibrium concentrations of the reaction shown, the terms in the "change" column are ____ M²⁺ + 4L ML₄⁺ [M²⁺] [L] [ML₄⁺] I 0.10 M 0.32 M 0 M C E

What is the difference between " $\Delta$ G" and " $\Delta$ G $\degree$ "?

The reaction of bromine gas with chlorine gas, shown here, has a K_p value of 7.20. If a closed vessel was charged with the two reactants, each at an initial partial pressure of 0.500 atm, what would be the equilibrium partial pressure of BrCl(g) ? Br₂(g) + Cl₂(g) 2BrCl(g)

A reaction X + 2Y $\rightarrow$ 3Z is started with 1.0 M Z and no X or Y. To calculate the equilibrium concentrations of all species using an ICE table, which of the following would you enter in the Z column for the C row?

To solve an equation of the form ax² + bx + c = 0 for values of x, use __________