Skip to main content
Pearson+ LogoPearson+ Logo
Ch.20 - Electrochemistry
All textbooksBrown 14th EditionCh.20 - ElectrochemistryProblem 77
Chapter 20, Problem 77

(a) Suppose that an alkaline battery was manufactured using cadmium metal rather than zinc. What effect would this have on the cell emf?

Verified step by step guidance
1
Identify the role of zinc in a typical alkaline battery, which acts as the anode where oxidation occurs, contributing to the overall cell potential.
Understand that cadmium, like zinc, can also act as an anode in electrochemical cells, but it has a different standard reduction potential.
Look up the standard reduction potentials for both zinc (Zn) and cadmium (Cd) from a standard reduction potential table. Zinc has a standard reduction potential of -0.76 V, while cadmium has a standard reduction potential of -0.40 V.
Calculate the cell emf for both scenarios: the original battery with zinc and the hypothetical battery with cadmium, using the formula: \( E_{cell} = E_{cathode} - E_{anode} \).
Compare the calculated cell emfs to determine the effect of substituting cadmium for zinc on the cell emf, noting that a higher reduction potential for cadmium would result in a lower cell emf compared to zinc.
Related Practice
Textbook Question

Heart pacemakers are often powered by lithium–silver chromate 'button' batteries. The overall cell reaction is 2 Li(s) + Ag2CrO4(s) → Li2CrO4(s) + 2 Ag(s) (a) Lithium metal is the reactant at one of the electrodes of the battery. Is it the anode or the cathode?

438
views
Textbook Question

Heart pacemakers are often powered by lithium–silver chromate 'button' batteries. The overall cell reaction is 2 Li(s) + Ag2CrO4(s) → Li2CrO4(s) + 2 Ag(s) (b) Choose the two half-reactions from Appendix E that most closely approximate the reactions that occur in the battery. What standard emf would be generated by a voltaic cell based on these half-reactions?

840
views
Open Question
The question is quite comprehensive but could be slightly confusing due to the presentation of chemical equations. Here is a more reader-friendly version: 'Mercuric oxide dry-cell batteries are often used where a flat discharge voltage and long life are required, such as in watches and cameras. The two half-cell reactions that occur in the battery are: 1. HgO(s) + H2O(l) + 2 e⁻ → Hg(l) + 2 OH⁻(aq) 2. Zn(s) + 2 OH⁻(aq) → ZnO(s) + H2O(l) + 2 e⁻ (b) The value of E°_red for the cathode reaction is +0.098 V. The overall cell potential is +1.35 V. Assuming that both half-cells operate under standard conditions, what is the standard reduction potential for the anode reaction?'
Textbook Question

In some applications nickel–cadmium batteries have been replaced by nickel–zinc batteries. The overall cell reaction for this relatively new battery is: 2 H2O(l) + 2 NiO(OH)(s) + Zn(s) → 2 Ni(OH)2(s) + Zn(OH)2(s) (b) What is the anode half-reaction?

622
views
Textbook Question

In some applications nickel–cadmium batteries have been replaced by nickel–zinc batteries. The overall cell reaction for this relatively new battery is: 2 H2O(l) + 2 NiO(OH)(s) + Zn(s) → 2 Ni(OH)2(s) + Zn(OH)2(s) (c) A single nickel–cadmium cell has a voltage of 1.30 V. Based on the difference in the standard reduction potentials of Cd2+ and Zn2+, what voltage would you estimate a nickel–zinc battery will produce? (d) Would you expect the specific energy density of a nickel–zinc battery to be higher or lower than that of a nickel–cadmium battery?

596
views
Open Question
In a Li-ion battery, the composition of the cathode is LiCoO2 when completely discharged. On charging, approximately 50% of the Li+ ions can be extracted from the cathode and transported to the graphite anode where they intercalate between the layers. (b) If the LiCoO2 cathode has a mass of 10 g (when fully discharged), how many coulombs of electricity can be delivered on completely discharging a fully charged battery?