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Chapter 20: Problem 28

Indicate whether each statement is true or false: (a) The anode is the electrode at which oxidation takes place. (b) A voltaic cell always has a positive emf. (c) A salt bridge or permeable barrier is necessary to allow a voltaic cell to operate.

Short Answer

Expert verified
(a) True: The anode is the electrode at which oxidation takes place, where chemical species lose electrons. (b) True: A voltaic cell always has a positive emf, producing electricity through a spontaneous redox reaction. (c) True: A salt bridge or permeable barrier is necessary to maintain electrical neutrality and allow a voltaic cell to operate.

Step by step solution

01

(a) The anode is the electrode at which oxidation takes place.

This statement is true. In an electrochemical cell, the anode is the electrode where oxidation occurs. Oxidation can be remembered as the process where a species loses electrons. So at the anode, the chemical species lose their electrons and generate an electric current.
02

(b) A voltaic cell always has a positive emf.

This statement is true. A voltaic cell, also known as a galvanic cell, is an electrochemical cell that produces electricity through a spontaneous redox reaction. The emf is a measure of the voltage produced by the cell. Since the reaction is spontaneous, the cell generates a positive emf. If the emf were negative, it would be referred to as an electrolytic cell, which uses an external voltage source to drive a non-spontaneous redox reaction.
03

(c) A salt bridge or permeable barrier is necessary to allow a voltaic cell to operate.

This statement is true. A salt bridge or permeable barrier serves a critical role in the functioning of a voltaic cell. It is responsible for maintaining electrical neutrality by allowing the migration of ions between the two half-cells. Without a salt bridge or permeable barrier, the charge buildup at the electrodes would quickly stop the redox reaction, and hence no electric current would be produced. In conclusion, all three statements (a), (b), and (c) are true.

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Most popular questions from this chapter

(a) What is the definition of the volt? (b) Do all voltaic cells produce a positive cell potential?

For each of the following balanced oxidation-reduction reactions, (i) identify the oxidation numbers for all the elements in the reactants and products and (ii) state the total number of electrons transferred in each reaction. (a) \(14 \mathrm{H}^{+}(a q)+2 \mathrm{Mn}^{2+}(a q)+5 \mathrm{NaBiO}_{3}(s)\) $\quad \longrightarrow 7 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{MnO}_{4}^{-}+5 \mathrm{Bi}^{3+}(a q)+5 \mathrm{Na}^{+}(a q)$ (b) $2 \mathrm{KMnO}_{4}(a q)+3 \mathrm{Na}_{2} \mathrm{SO}_{3}(a q)+\mathrm{H}_{2} \mathrm{O}(l)\( \)\quad \longrightarrow 2 \mathrm{MnO}_{2}(s)+3 \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+2 \mathrm{KOH}(a q)$ (c) $\mathrm{Cu}(s)+2 \mathrm{AgNO}_{3}(a q) \longrightarrow 2 \mathrm{Ag (s)+\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(a q)$

If the equilibrium constant for a two-electron redox reaction at $298 \mathrm{~K}\( is \)2.2 \times 10^{5},\( calculate the corresponding \)\Delta G^{\circ}\( and \)E^{\circ}$.

Indicate whether each of the following statements is true or false: (a) If something is reduced, it is formally losing electrons. (b) A reducing agent gets oxidized as it reacts. (c) An oxidizing agent is needed to convert \(\mathrm{CO}\) into \(\mathrm{CO}_{2}\).

For a spontaneous reaction $\mathrm{A}(a q)+\mathrm{B}(a q) \longrightarrow \mathrm{A}^{-}(a q)+$ \(\mathrm{B}^{+}(a q),\) answer the following questions: (a) If you made a voltaic cell out of this reaction, what halfreaction would be occurring at the cathode, and what half reaction would be occurring at the anode? (b) Which half-reaction from (a) is higher in potential energy? (c) What is the sign of \(E_{\text {cell }}^{\circ}\) ?
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