Chapter 19, Problem 14PE

Calculate $\Delta G°$ for the reactions that take place in the galvanic cells as written in Practice Exercises 19.11 and 19.12.

Write each of the following equations so that they represent spontaneous reactions at standard state.

(a) $2{\text{Br}}^{\text{-}}\left(aq\right)+{\text{I}}_{\text{2}}\left(s\right)\to {\text{Br}}_{\text{2}}\left(aq\right)+2{\text{I}}^{\text{-}}\left(aq\right)$

(b) ${\text{Mn}}^{\text{2+}}\left(aq\right)+5{\text{Ag}}^{\text{+}}\left(aq\right)+4{\text{H}}_{\text{2}}\text{O}\to {\text{MnO}}_{\text{4}}{}^{\text{-}}\left(aq\right)+5\text{Ag}\left(s\right)+8{\text{H}}^{\text{+}}\left(aq\right)$

(Hint: Determine the sign of the calculated standard cell potential.)

Under standard state conditions, which of the following reactions occur spontaneously? Justify your answer.

$2{\text{Br}}^{\text{-}}\left(aq\right)+2\text{HOCl}\left(aq\right)+2{\text{H}}^{\text{+}}\left(aq\right)\to {\text{Br}}_{\text{2}}\left(aq\right)+{\text{Cl}}_{\text{2}}\left(g\right)+2{\text{H}}_{\text{2}}\text{O}$

${\text{3Zn}}^{\text{2+}}\left(aq\right)+2\text{Cr}\left(s\right)\to 3\text{Zn}\left(s\right)+2{\text{Cr}}^{\text{3+}}\left(aq\right)$