Chemistry

Problem

A portable sensor requires a power source that delivers at least +1.10 V under standard conditions. You have access only to the four half-reactions in the table. Ag

^{+}

+ e

^{-}

→ Ag(s)

E^{\circ}=+0.80\,\text{V}

^{2+}

+ 2 e

^{-}

→ Pb(s)

E^{\circ}=-0.13\,\text{V}

^{2+}

+ 2 e

^{-}

→ Ni(s)

E^{\circ}=-0.25\,\text{V}

^{2+}

+ 2 e

^{-}

→ Zn(s)

E^{\circ}=-0.76\,\text{V}

Which pair of half-reactions, when combined spontaneously, will meet or exceed the required voltage? a) Ag

^{+}

/Ag as the cathode and Ni/Ni

^{2+}

as the anode b) Zn

^{2+}

/Zn as the cathode and Ag/Ag

^{+}

as the anode c) Ag

^{+}

/Ag as the cathode and Zn/Zn

^{2+}

as the anode d) Pb

^{2+}

/Pb as the cathode and Zn/Zn

^{2+}

as the anode

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