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Problem 1a
(a) Based on the following energy profile, predict whether kf > kr or kf < kr. [Section 15.1]
Problem 2
The following diagrams represent a hypothetical reaction A ¡ B, with A represented by red spheres and B represented by blue spheres. The sequence from left to right represents the system as time passes. Does the system reach equilibrium? If so, in which diagram(s) is the system in equilibrium? [Sections 15.1 and 15.2]
- Consider the equilibrium Na2O(s) + SO2(g) ⇌ Na2SO3(s). (a) Write the equilibrium-constant expression for this reaction in terms of partial pressures. (b) All the compounds in this reaction are soluble in water. Rewrite the equilibrium-constant expression in terms of molarities for the aqueous reaction.
Problem 3
- A chemist at a pharmaceutical company is measuring equilibrium constants for reactions in which drug candidate molecules bind to a protein involved in cancer. The drug molecules bind the protein in a 1:1 ratio to form a drug–protein complex. The protein concentration in aqueous solution at 25 _x001F_C is 1.50 * 10^-6 M. Drug A is introduced into the protein solution at an initial concentration of 2.00 * 10^-6 M. Drug B is introduced into a separate, identical protein solution at an initial concentration of 2.00 * 10^-6 M. At equilibrium, the drug A–protein solution has an A–protein complex concentration of 1.00 * 10^-6 M, and the drug B solution has a B–protein complex concentration of 1.40 * 10^-6 M. Calculate the Kc value for the A–protein binding reaction and for the B–protein binding reaction. Assuming that the drug that binds more strongly will be more effective, which drug is the better choice for further research?
Problem 4
Problem 4d
The following diagram represents a reaction shown going to completion. Each molecule in the diagram represents 0.1 mol, and the volume of the box is 1.0 L. (d) Assuming that all of the molecules are in the gas phase, calculate n, the change in the number of gas molecules that accompanies the reaction. [Section 15.2]
Problem 6
Ethene (C2H4) reacts with halogens (X2) by the following reaction:
C2H4(𝑔) + X2(𝑔) ⇌ C2H4X2(𝑔)
The following figures represent the concentrations at equilibrium at the same temperature when X2 is Cl2 (green), Br2 (brown), and I2 (purple). List the equilibria from smallest to largest equilibrium constant. [Section 15.3]
- True or false: When the temperature of an exothermic reaction increases, the rate constant of the forward reaction decreases, which leads to a decrease in the equilibrium constant, Kc.
Problem 7
Problem 7a
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? a. There will be less PbO2 remaining in vessel A,