20. Electrochemistry

Multiple Choice

What is the value of the cell potential for the 4 electron transfer reaction below if the equilibrium mixture contains 0.255 M of CH₄, 1.10 M CO₂, 0.388 M CO and 0.250 M H₂at 25ºC?

CH₄ (g) + CO₂ (g) ⇌. 2 CO (g) + 2 H₂ (g)

108

comments

Multiple Choice

Given the reaction: 2 Cl2 (g) + 2 H2O (g) ⇌ 4 HCl (g) + O2 (g) Kp = 7.5x10-2, calculate the Gibbs Free Energy change for the reaction below at 30ºC.

8 HCl (g) + 2 O2 (g) ⇌ 4 Cl2 (g) + 4 H2O (g)

137

For each of the following reactions, write a balanced equation, calculate the standard emf, calculate ∆G° at 298 K, and calculate the equilibrium constant K at 298 K. (c) In basic solution, Cr1OH231s2 is oxidized to CrO42-1aq2 by ClO-1aq2.

224

For each of the following reactions, write a balanced equation, calculate the standard emf, calculate ∆G° at 298 K, and calculate the equilibrium constant K at 298 K. (a) Aqueous iodide ion is oxidized to I21s2 by Hg22+1aq2.

529

rank

For each of the following reactions, write a balanced equation, calculate the standard emf, calculate ∆G° at 298 K, and calculate the equilibrium constant K at 298 K. (b) In acidic solution, copper(I) ion is oxidized to copper(II) ion by nitrate ion.

304

Calculate the equilibrium constant for each of the reactions in Problem 65.

1505

Consider the reaction shown here occurring at 25 °C. Cr(s) + Cd2+(aq) ¡ Cr2+(aq) + Cd(s) Determine Ec°ell, K, and ∆Gr°xn for the reaction and complete the table. [Cd2+] [Cr2+] Q Ecell 𝚫Grxn 1.00 1.00 1.00 * 10-5 4.18 * 10-4 1.00 1.00 * 10-5 1.00 1.00

696

Calculate ∆Gr°xn and K for each reaction. b. The reaction of Cr3+(aq) and Cr(s) to form Cr2+(aq). [The electrode potential of Cr2+(aq) to Cr(s) is -0.91 V.]

661

Calculate ∆Gr°xn and K for each reaction. a. The reaction of Cr2+(aq) with Cr2O7^2-(aq) in acid solution to form Cr3+(aq).

793

A mercury battery uses the following electrode half-reactions: (b) Calculate ∆G° (in kilojoules) and K at 25 °C for the cell reaction.

630

Consider the following half-reactions and E° values: (c) Write the cell reaction for part (b), and calculate the values of E°, ∆G° (in kilojoules), and K for this reaction at 25 °C

598

Consider a galvanic cell that utilizes the following half-reactions:

(b) What are the values of E° and the equilibrium constant K for the cell reaction at 25 °C?

540

The nickel–iron battery has an iron anode, an NiO(OH) cathode, and a KOH electrolyte. This battery uses the follow-ing half-reactions and has an E° value of 1.37 V at 25 °C. (b) Calculate ∆G° (in kilojoules) and the equilibrium con-stant K for the cell reaction at 25 °C.

817

Experimental solid-oxide fuel cells that use butane (C4H10) as the fuel have been reported recently. These cells contain composite metal/metal oxide electrodes and a solid metal oxide electrolyte. The cell half-reactions are (b) Use the thermodynamic data in Appendix B to calculate the values of E° and the equilibrium constant K for the cell reaction at 25 °C. Will E° and K increase, decrease, or remain the same on raising the temperature?

222

The half-reactions that occur in ordinary alkaline batteries can be written as In 1999, researchers in Israel reported a new type of alkaline battery, called a 'super-iron' battery. This battery uses the same anode reaction as an ordinary alkaline battery but involves the reduction of FeO42- ion (from K2FeO4) to solid Fe(OH)3 at the cathode. (a) Use the following standard reduction potential and any data from Appendixes C and D to calculate the stan-dard cell potential expected for an ordinary alkaline battery:

677

Gold metal is extracted from its ore by treating the crushed rock with an aerated cyanide solution. The unbalanced equation for the reaction is (b) Use any of the following data at 25 °C to calculate ∆G° for this reaction at 25 °C: Kf for Au(CN)2- = 6.2 x 10^38, Ka for HCN = 4.9 x 10^-10, and standard reduction potentials are

496

Open Question

Consider the following reaction and select the false statement below. NaI + 3 HOCl → NaIO₃ + 3 HCl