The cell $\text{Fe}(s) \mid \text{Fe}^{2+}(aq) \parallel \text{Cu}^{2+}(aq) \mid \text{Cu}(s)$ has $E^\circ = 0.78\ \text{V}$ and $n = 2$ at $298\ \text{K}$. At one moment its emf is $0.85\ \text{V}$. What is the reaction quotient $Q$ at that moment?