Water is an amphoteric compound that also acts as a good solvent of polar and ionic compounds. Metal-air batteries are electrochemical cells that generate electrical energy from the reaction of metal anodes with air. The standard electrode potentials for the zinc-air battery are shown. $$\(\left[\mathrm{Zn}(\mathrm{OH})_{4}\right]^{2-}+2 \mathrm{e}^{-} \rightleftharpoons \mathrm{Zn}+4 \mathrm{OH}^{-} \quad E^{\ominus}=-1.22 \mathrm{~V}\)$$ $$\(\frac{1}{2} \mathrm{O}_{2}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \rightleftharpoons 2 \mathrm{OH}^{-} \quad E^{\ominus}=+0.40 \mathrm{~V}\)$$ (i) Calculate the standard cell potential, $$\(E_{\text {cell }}^{\ominus}\)$$, of the zinc-air battery. $$\[ E_{\text {cell }}^{\ominus}= \]$$ ................................................... V (ii) The zinc-air battery usually operates at pH 11 and 298 K . The overall cell potential is dependent on $$\(\left[\mathrm{OH}^{-}\right]\)$$. The Nernst equation shows how the electrode potential at the cathode changes with $$\(\left[\mathrm{OH}^{-}\right]\)$$. $$\[ E=0.40-\left(\frac{0.059}{z}\right) \log \left(\left[\mathrm{OH}^{-}\right]^{2}\right) \]$$ Calculate the electrode potential, $$\(E\)$$, at pH 11 . $$\[ E= \]$$ ................................................... $$\(\mathrm{V}\)$$

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