Question 1

For the reaction A + B → C + D, ΔG° = -5.00 kcal/mol. What is the corresponding equilibrium constant at  
R = 1.987 cal/mol∙K.

Accepted Answer

The answer of For the reaction A + B →...

Question 2

Given a ΔG°of -8.0 kJ/mol at 25°C, calculate the corresponding K. [R = 8.314 J/K∙ mol]

Accepted Answer

The answer of Given a ΔG°of -8.0 kJ/mol at...

Question 3

Given a K of 0.45 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Accepted Answer

The answer of Given a K of 0.45 at 25°C,...

Question 4

Given a K of 2.2 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Accepted Answer

The answer of Given a K of 2.2 at 25°C,...

Question 5

Which is a measure of the randomness of a system?

Accepted Answer

Entropy is a thermodynamic property that measures the randomness or disorder of a system. It is related to the number of possible microscopic arrangements of the system that would result in a given macroscopic state. The more disordered a system is, the higher its entropy. Enthalpy, free energy, halogenation, and stoichiometry are all important concepts in chemistry, but they do not specifically measure the randomness of a system.

Question 6

If the percentage of the axial onformer (on the product side of the reaction) is 42%, what is the ΔG° (in kJ/mol) for the reaction at 25°C? [R = 8.314 J/K∙ mol]

Accepted Answer

The answer of If the percentage of the axial onformer...

Question 7

Consider the transformation of A to B (i.e., A →
B). If at equilibrium at 25°C the concentration of A is 20% of the initial concentration of A, determine the value of  
(in kcal/mol) for this reaction. R = 1.987 cal/mol∙K.

Accepted Answer

The answer of Consider the transformation of A to B...

Question 8

If a reaction is exothermic, then ________.

Accepted Answer

Exothermic reactions release heat energy, which means that the enthalpy change (ΔH°) is negative. Therefore, choice C is the correct answer.

Choices A and B refer to the entropy change, which is related to the degree of disorder in a system. Although entropy may increase or decrease during a reaction, it is not directly related to the exothermic or endothermic nature of the reaction.

Choice D is the opposite of the correct answer. Endothermic reactions absorb heat energy, so ΔH° is positive, not negative.

Choice E is partially correct, as B is a valid answer for the entropy change, but D is not correct for ΔH°.

Question 9

Which of the following is true for the initiation step of a free radical chlorination reaction?

Accepted Answer

The initiation step of a free radical chlorination reaction involves breaking the chlorine-chlorine bond using UV light or heat, which requires energy and results in an increase in entropy due to the formation of two chlorine radicals. Therefore, ΔH° and ΔS° both have positive values, making choice A the correct answer.

Question 10

Given a reaction in which reactant A is converted only to product B at 25°C, what K_eq results if at equilibrium 80% of A has become B?

Accepted Answer

The answer of Given a reaction in which reactant A...

Question 11

Which of the following statements correctly describes the contribution of  to

Accepted Answer

The given compounds have identical enthalpy (H) values, but they differ in their entropy (S) values. Therefore, the contribution of the entropy term (TΔS) to the overall Gibbs free energy change (ΔG°) increases with increasing temperature. At high temperatures, the entropy term dominates in determining the sign and magnitude of ΔG°. Therefore, choice B is the correct answer.

Question 12

Assume the reaction A + B → C + D proceeds to equilibrium. Calculate the equilibrium concentration of D at  given that the starting concentrations of A and B are 2M and that △G° for the reaction is

Accepted Answer

The answer of Assume the reaction A + B →...

Question 13

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is ________ and the % conversion is ________.

Accepted Answer

The answer of Consider the reaction of A being converted...

Question 14

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH₃Cl ↔ CH₃OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

Accepted Answer

From the given ΔG° value of -91.1 kJ/mole and using the formula ΔG° = -RTlnKeq, we can calculate Keq = e^(-ΔG°/RT). At 25°C (298 K), Keq = e^(-(-91.1*1000)/(8.315*298)) = 1.51 x 10^16. This value is very large, indicating that the reaction proceeds to near completion from left to right under standard conditions. Option A is the correct choice. Option C is incorrect since the equilibrium constant does not change with temperature.

Question 15

If the equilibrium constant (K_eq) of a reaction is 0.5 then which of the following that must be true?

Accepted Answer

If the equilibrium constant (K) of a reaction is less than 1 (K < 1), it means that the reaction favors the reactants over the products at equilibrium. This implies that the Gibbs free energy change (ΔG) for the reaction is positive, indicating that the reaction is not spontaneous in the forward direction under standard conditions.

Question 16

Given the pK_a values for the two acids below, what would you expect the K_eq for this reaction to be?

Accepted Answer

The equilibrium constant for the reaction of two acids is equal to the product of their dissociation constants. K_eq = [H3O+][A-]/[HA], and since the dissociation constants for both acids are greater than 1 (as indicated by the pK_a values), their product will be even greater than 1. Therefore, K_eq is greater than 1, and the correct answer is C.

Question 17

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is ________ and the % conversion is ________.

Accepted Answer

The answer of Consider the reaction of A being converted...

Question 18

In an exothermic reaction, are stronger bonds broken and weaker bonds formed or are weaker bonds broken and stronger bonds formed?

Accepted Answer

The answer of In an exothermic reaction, are stronger bonds...

Question 19

Which of the following correctly expresses the standard Gibbs free energy change of a reaction in terms of the changes in enthalpy and entropy?

Accepted Answer

This is the correct expression for the standard Gibbs free energy change of a reaction in terms of the changes in enthalpy and entropy. The equation states that the standard Gibbs free energy change (ΔG°) is equal to the change in enthalpy (ΔH°) minus the product of temperature (T) and the change in entropy (ΔS°).

Question 20

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is ________ and the % conversion is ________.

Accepted Answer

We can use the relationship between ΔG° and K to find the equilibrium constant for the reaction:

ΔG° = -RT lnK

Solving for K, we get:

K = e^(-ΔG°/RT)

Plugging in the given values, we get:

K = e^(-11eab5e1_c8c5_8be4_9bae_f59b3a2184ad_TB6199_11/(8.314 J/mol*K * 298 K)) = 2.3

Using the equilibrium constant and the stoichiometry of the reaction, we can find the percentage conversion of A to B:

K = [B]/[A] = (x/[A]0)/(1-x), where x is the fraction of A that has reacted and [A]0 is the initial concentration of A.

Solving for x, we get:

x = K[A]0/(1+K[A]0) = 0.7

Therefore, the % conversion is 70%, which is closest to answer choice D, 2.3; 70%.

Quiz 4: The Study of Chemical Reactions

For the reaction A + B → C + D, ΔG° = -5.00 kcal/mol. What is the corresponding equilibrium constant at R = 1.987 cal/mol∙K.

Given a ΔG°of -8.0 kJ/mol at 25°C, calculate the corresponding K. [R = 8.314 J/K∙ mol]

Given a K of 0.45 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Given a K of 2.2 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Which is a measure of the randomness of a system?

If the percentage of the axial onformer (on the product side of the reaction) is 42%, what is the ΔG° (in kJ/mol) for the reaction at 25°C? [R = 8.314 J/K∙ mol]

Consider the transformation of A to B (i.e., A → B). If at equilibrium at 25°C the concentration of A is 20% of the initial concentration of A, determine the value of (in kcal/mol) for this reaction. R = 1.987 cal/mol∙K.

If a reaction is exothermic, then ________.

Which of the following is true for the initiation step of a free radical chlorination reaction?

Given a reaction in which reactant A is converted only to product B at 25°C, what K_eq results if at equilibrium 80% of A has become B?

Which of the following statements correctly describes the contribution of to

Assume the reaction A + B → C + D proceeds to equilibrium. Calculate the equilibrium concentration of D at given that the starting concentrations of A and B are 2M and that △G° for the reaction is

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH₃Cl ↔ CH₃OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

If the equilibrium constant (K_eq) of a reaction is 0.5 then which of the following that must be true?

Given the pK_a values for the two acids below, what would you expect the K_eq for this reaction to be?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .

In an exothermic reaction, are stronger bonds broken and weaker bonds formed or are weaker bonds broken and stronger bonds formed?

Which of the following correctly expresses the standard Gibbs free energy change of a reaction in terms of the changes in enthalpy and entropy?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .

Quiz 4: The Study of Chemical Reactions

For the reaction A + B → C + D, ΔG° = -5.00 kcal/mol. What is the corresponding equilibrium constant at R = 1.987 cal/mol∙K.

Given a ΔG° of -8.0 kJ/mol at 25°C, calculate the corresponding K. [R = 8.314 J/K∙ mol]

Given a K of 0.45 at 25°C, calculate the corresponding ΔG° in kJ/mol. [R = 8.314 J/K∙ mol]

Given a K of 2.2 at 25°C, calculate the corresponding ΔG° in kJ/mol. [R = 8.314 J/K∙ mol]

Which is a measure of the randomness of a system?

If the percentage of the axial onformer (on the product side of the reaction) is 42%, what is the ΔG° (in kJ/mol) for the reaction at 25°C? [R = 8.314 J/K∙ mol]

Consider the transformation of A to B (i.e., A → B). If at equilibrium at 25°C the concentration of A is 20% of the initial concentration of A, determine the value of (in kcal/mol) for this reaction. R = 1.987 cal/mol∙K.

If a reaction is exothermic, then ________.

Which of the following is true for the initiation step of a free radical chlorination reaction?

Given a reaction in which reactant A is converted only to product B at 25°C, what Keq results if at equilibrium 80% of A has become B?

Which of the following statements correctly describes the contribution of to

Assume the reaction A + B → C + D proceeds to equilibrium. Calculate the equilibrium concentration of D at given that the starting concentrations of A and B are 2M and that △G° for the reaction is

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the Keq is ________ and the % conversion is ________.

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH3Cl ↔ CH3OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

If the equilibrium constant (Keq) of a reaction is 0.5 then which of the following that must be true?

Given the pKa values for the two acids below, what would you expect the Keq for this reaction to be?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the Keq is ________ and the % conversion is ________.

In an exothermic reaction, are stronger bonds broken and weaker bonds formed or are weaker bonds broken and stronger bonds formed?

Which of the following correctly expresses the standard Gibbs free energy change of a reaction in terms of the changes in enthalpy and entropy?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the Keq is ________ and the % conversion is ________.

Given a ΔG°of -8.0 kJ/mol at 25°C, calculate the corresponding K. [R = 8.314 J/K∙ mol]

Given a K of 0.45 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Given a K of 2.2 at 25°C, calculate the corresponding ΔG°in kJ/mol. [R = 8.314 J/K∙ mol]

Given a reaction in which reactant A is converted only to product B at 25°C, what K_eq results if at equilibrium 80% of A has become B?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH₃Cl ↔ CH₃OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

If the equilibrium constant (K_eq) of a reaction is 0.5 then which of the following that must be true?

Given the pK_a values for the two acids below, what would you expect the K_eq for this reaction to be?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is the K_eq is and the % conversion is .