A student operates an electrolytic cell in which an inert platinum cathode is…

CHEMISTRY · Single correct · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry

Problem

A student operates an electrolytic cell in which an inert platinum cathode is immersed in a 1.0 M AgNO_3 solution. After several minutes, a visible coating of silver metal forms on the cathode surface. Which of the following best explains the increase in cathode mass? (a) Silver metal at the cathode loses electrons and is oxidized to

\mathrm{Ag^+}

; the resulting

\mathrm{Ag_2O}

deposits increase the mass. (b) Positively charged

\mathrm{Ag^+}

ions are attracted to the cathode and crystallize as solid

\mathrm{AgNO_3}

without undergoing any redox change. (c)

\mathrm{Ag^+}

ions in solution gain electrons at the cathode, forming solid

\mathrm{Ag}

that plates onto the electrode. (d) Water molecules are reduced at the cathode to produce

\mathrm{H_2}

and

\mathrm{OH^-}

; the

\mathrm{OH^-}

then precipitates

\mathrm{AgOH}

onto the electrode surface.

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