Skip to main content
Ch.15 - Chemical Equilibrium
Chapter 15, Problem 13b

Suppose that the gas-phase reactions A → B and B → A are both elementary reactions with rate constants of 4.7×10−3  s−1 and 5.8×10−1 s−1, respectively. (b) Which is greater at equilibrium, the partial pressure of A or the partial pressure of B?

Verified Solution

Video duration:
3m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Equilibrium Constant

The equilibrium constant (K) for a reaction at equilibrium is defined as the ratio of the concentrations (or partial pressures) of the products to the reactants, each raised to the power of their stoichiometric coefficients. For the reactions A ⇌ B, K can be calculated using the rate constants of the forward (k₁) and reverse (k₂) reactions: K = k₁/k₂. This constant helps determine the relative amounts of A and B at equilibrium.
Recommended video:
Guided course
01:14
Equilibrium Constant K

Rate Constants

Rate constants (k) are specific to each reaction and indicate the speed at which a reaction proceeds. In this case, the rate constant for the forward reaction (A → B) is 4.7×10⁻³ s⁻¹, while for the reverse reaction (B → A) it is 5.8×10⁻¹ s⁻¹. The magnitude of these constants influences the equilibrium position, with larger constants favoring the formation of products or reactants.
Recommended video:
Guided course
00:45
Rate Constant Units

Le Chatelier's Principle

Le Chatelier's Principle states that if a system at equilibrium is disturbed, the system will adjust to counteract the disturbance and restore a new equilibrium. In the context of the given reactions, knowing the rate constants allows us to predict which species will be favored at equilibrium, as the system will shift towards the side with the lower energy or higher stability based on the rate constants.
Recommended video:
Guided course
07:32
Le Chatelier's Principle
Related Practice
Textbook Question

When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO2(𝑠) ⇌ 2PbO(𝑠) + O2(𝑔). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true? (c) The amount of PbO2 remaining in each vessel will be the same. [Find more in Section 15.4]

304
views
Textbook Question

The reaction A2 + B2 ⇌ 2 AB has an equilibrium constant Kc = 1.5. The following diagrams represent reaction mixtures containing A2 molecules (red), B2 molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?

1344
views
Textbook Question

The diagram shown here represents the equilibrium state for the reaction A2(𝑔) + 2B(𝑔) ⇌ 2AB(𝑔). (a) Assuming the volume is 2 L, calculate the equilibrium constant 𝐾𝑐 for the reaction.

660
views
Textbook Question

The equilibrium constant for the dissociation of molecular iodine, I2(𝑔) ⇌ 2 I(𝑔), at 800 K is 𝐾𝑐 = 3.1×10−5. (b) Assuming both forward and reverse reactions are elementary reactions, which reaction has the larger rate constant, the forward or the reverse reaction?

1209
views
Textbook Question

Write the expression for 𝐾𝑐 for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.

(e) 2Ag(𝑠) + Zn2+(𝑎𝑞) ⇌ 2 Ag+(𝑎𝑞) + Zn(𝑠)

573
views
Textbook Question

Write the expressions for 𝐾𝑐 for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.

(b) Ti(𝑠) + 2Cl2(𝑔) ⇌ TiCl4(𝑙)

459
views