For the cell Zn|Zn²⁺‖Cu²⁺|Cu with $E^0_{cell} = 1.10$ V, the equilibrium constant $K$ at 298 K ($n=2$, RT/F = 0.0257) is approximately:

From $\Delta G^0 = -RT\ln K = -nFE^0$: $\ln K = nFE^0/RT$ = $2(96485)(1.10)/(8.314 \times 298) \approx 85.7$. $K = e^{85.7} \approx 10^{37.2}$ ≈ $10^{37}$. The huge $K$ confirms the Daniell cell reaction is essentially irreversible.