# Determining efficiency of fuel cells

by boddhisattva
Tags: cells, determining, efficiency, fuel
 P: 6 Hi I need to compare solid working with $\frac{1}{2}O_{2}+H_{2}O+2e^{-} \rightarrow 2OH^{-}$ and $H_{2}+2OH^{-} \rightarrow 2H_{2}O+2e^{-}$ and liquid fuel cells working with $H_{2}\rightarrow 2H^{+}+2e^{-}$ and $\frac{1}{2}O_{2}+2H^{+}+2e^{-} \rightarrow H_{2}O$ My idea was to compare the required electrical energy (which I know by $dt U I$ and the chemical energy given by $Q \cdot n_{H_{2}O}=Q\cdot n_{H_{2}O}=Q\cdot\nu_{gas}\cdot n_{O_{2}}=Q\cdot\nu_{O_{2}}\cdot\frac{PV_{O_{2}}}{n_{O_{2}}RT}$ where [itex] \nu _{O_{2}} [itex] is a coefficient that is equal to 1/2 in the case of solid fluel cells. My question is simple: what is [itex] \nu _{O_{2}} [itex] equal to in the case of liquid cell since there is a double equation and that we don't know which portion of OH^{-} of the reductive equation is used in the oxydative equation. Any help would be helpful, thanks

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