The gas evolved at the anode when \(\mathrm{K}_{2} \mathrm{SO}_{4}(\mathrm{aq})\) is electrolyzed between Pt electrodes is most likely to be (a) \(\mathrm{O}_{2} ;\) (b) \(\mathrm{H}_{2} ;\) (c) \(\mathrm{SO}_{2} ;\) (d) \(\mathrm{SO}_{3} ;\) (e) a mixture of sulfur oxides.

Short Answer

Expert verified
(a) \(O_2\) is the gas most likely to be evolved at the anode during the electrolysis of \(K_{2}SO_{4}(aq)\) between Pt electrodes

Step by step solution

01

Identify the Potential Oxidation Reactions

The oxidation half-reaction could involve either the sulfate ion (SO4^2-) from the \(K_{2}SO_{4}(aq)\) or water (H2O). Here are the potential reactions: 1) The sulfate ion could lose electrons (be oxidized) to form various sulfur oxides and oxygen gas. This can be represented as follows: \(SO_4^{2-} -> SO_2 + O_2 + 2e^-; SO_4^{2-} -> SO_3 + 1/2O_2 + 2e^-\) 2) Water could lose electrons to form oxygen gas and hydrogen ions, and this can be represented as: \(2H_2O -> O_2 + 4H^+ + 4e^-\)
02

Determine Which reaction is More Likely at the Anode

The reaction that occurs is the one that requires the least energy (the one that is most thermodynamically favorable). When compared, the oxidation of water to form oxygen gas is much more likely than the oxidation of the sulfate ion to form sulfur oxides. This is primarily because the sulfur in the sulfate ion is already in its highest possible oxidation state (+6), and oxidation would violate the octet rule. Additionally, reactions that form oxygen, a diatomic molecule, are generally more favorable than those forming sulfur oxides.
03

Answer the question

Based on the analysis, the gas evolved at the anode during the electrolysis of \(K_{2}SO_{4}(aq)\) between Pt electrodes is most likely to be oxygen (\(O_2\)). As a consequence, the correct answer is (a) \(O_2\)

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Most popular questions from this chapter

From the observations listed, estimate the value of \(E^{\circ}\) for the half- reaction \(\mathrm{M}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \longrightarrow \mathrm{M}(\mathrm{s})\) (a) The metal M reacts with HNO \(_{3}(\text { aq })\), but not with \(\mathrm{HCl}(\mathrm{aq}) ; \mathrm{M}\) displaces \(\mathrm{Ag}^{+}(\mathrm{aq}),\) but not \(\mathrm{Cu}^{2+}(\mathrm{aq})\) (b) The metal \(M\) reacts with \(\mathrm{HCl}(\mathrm{aq}),\) producing \(\mathrm{H}_{2}(\mathrm{g}),\) but displaces neither \(\mathrm{Zn}^{2+}(\text { aq })\) nor \(\mathrm{Fe}^{2+}(\mathrm{aq})\).

Calculate the quantity indicated for each of the following electrolyses. (a) \(\left[\mathrm{Cu}^{2+}\right]\) remaining in \(425 \mathrm{mL}\) of a solution that was originally \(0.366 \mathrm{M} \mathrm{CuSO}_{4},\) after passage of \(2.68 \mathrm{A}\) for 282 s and the deposition of Cu at the cathode (b) the time required to reduce \(\left[\mathrm{Ag}^{+}\right]\) in \(255 \mathrm{mL}\) of \(\mathrm{AgNO}_{3}(\mathrm{aq})\) from 0.196 to \(0.175 \mathrm{M}\) by electrolyzing the solution between \(\mathrm{Pt}\) electrodes with a current of \(1.84 \mathrm{A}\)

\(E_{\mathrm{cell}}^{\circ}=-0.0050 \mathrm{V}\) for the reaction, \(2 \mathrm{Cu}^{+}(\mathrm{aq})+\) \(\operatorname{sn}^{4+}(\mathrm{aq}) \longrightarrow 2 \mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{Sn}^{2+}(\mathrm{aq})\) (a) Can a solution be prepared that is \(0.500 \mathrm{M}\) in each of the four ions at \(298 \mathrm{K} ?\) (b) If not, in what direction must a net reaction Occur?

Explain the important distinctions between each pair of terms: (a) half- reaction and overall cell reaction; (b) voltaic cell and electrolytic cell; (c) primary battery and secondary battery; (d) \(E_{\text {cell }}\) and \(E_{\text {cell }}^{\circ}\).

Briefly describe each of the following ideas, methods, or devices: (a) salt bridge; (b) standard hydrogen electrode (SHE); (c) cathodic protection; (d) fuel cell.

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