Hydrogen-oxygen fuel cells are used in spacecraft to supply:

For the reaction $Cu^{2+}_{(aq)} + Fe_{(s)} \rightleftharpoons Fe^{2+}_{(aq)} + Cu_{(s)}$,calculate $\Delta G^o$ in Joules.
Given: $E^o_{Cu^{2+}/Cu} = +0.34 \ V$,$E^o_{Fe^{2+}/Fe} = -0.44 \ V$.

If the salt bridge between two half-cells is removed,the voltage of the cell:

At $25^{\circ} C$,the molar conductance at infinite dilution for the strong electrolytes $NaOH$,$NaCl$ and $BaCl_{2}$ are $248 \times 10^{-4}$,$126 \times 10^{-4}$ and $280 \times 10^{-4} \ S \ m^{2} \ mol^{-1}$ respectively. $\lambda_{m}^{o} Ba(OH)_{2}$ in $S \ m^{2} \ mol^{-1}$ is

How is the thermodynamic efficiency of a cell defined?

What is a secondary cell? Give examples of it.