The following reactions are used in batteries: Reaction I

Chapter 22, Problem 97P

(choose chapter or problem)

Reaction I is used in fuel cells, II in the automobile lead-acid battery, and III in an experimental high-temperature battery for powering electric vehicles. The aim is to obtain as much work as possible from a cell, while keeping its weight to a minimum.

(a) In each cell, find the moles of electrons transferred and \(\Delta G\).

(b) Calculate the ratio, in \(\mathrm{kJ} / \mathrm{g}\), of \(w_{\max }\) to mass of reactants for each of the cells. Which has the highest ratio, which the lowest, and why? (Note: For simplicity, ignore the masses of cell components that do not appear in the cell as reactants, including electrode materials, electrolytes, separators, cell casing, wiring, etc.)

I (\quad 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(f) \quad E_{c e l l}=1.23 \mathrm{~V}\)

II \(\mathrm{Pb}(s)+\mathrm{PbO}_{2}(s)+2 \mathrm{H}_{2} \mathrm{SO}_{4}(a q) \rightarrow 2 \mathrm{PbSO}_{4}(s)+2 \mathrm{H}_{2} \mathrm{O}() \quad E_{c e l}=2.04 \mathrm{~V}\)

III \(2 \mathrm{Na}(\mathrm{l})+\mathrm{FeCl}_{2}(s) \rightarrow 2 \mathrm{NaCl}(s)+\mathrm{Fe}(s) \quad E_{\text {cell }}=2.35 \mathrm{~V}\)

Equation Transcription:

Text Transcription:

2H_2(g)+O_2(g) rightarrow 2H_2O(f)    E_cell=1.23 V  

Pb(s)+PbO_2(s)+2H_2SO_4(aq) rightarrow 2PbSO_4(s)+2H_2O()    E_cell=2.04 V  

2Na(l)+FeCl_2(s) rightarrow 2NaCl(s)+Fe(s)   E_cell =2.35 V

Delta G  

kJ/g  

w_max