In which of the following method of purification, metal is converted to its volatile compound which is decomposed to give pure metal?
Which of the following statements are correct?
In the extraction of chlorine from brine ........... .
Why is an external emf of more than 2.2 V required for the extraction of $\mathrm{Cl}_2$ from brine?
$$2 \mathrm{Cl}^{-}(a q)+2 \mathrm{H}_2 \mathrm{O}(l) \longrightarrow 2 \mathrm{OH}^{-}(a q)+\mathrm{H}_2(g)+\mathrm{Cl}_2(g)$$
For the given reaction, value of $\Delta G^{\circ}$ is +422 kJ.
Using $\Delta G^{\circ}=-n F E^{\circ}$, the value of $E^{\circ}=-2.2 \mathrm{~V}$.
Therefore, an external emf greater than 2.2 V is required for the extraction of $\mathrm{Cl}_2$ from brine.
At temperature above 1073 K, coke can be used to reduce Fe 0 to Fe . How can you justify this reduction with Ellingham diagram?
Using Ellingham diagram, we observe that at temperature greater than 1073 K ; $\Delta G_{(\mathrm{C}, \mathrm{CO})}<\Delta G_{(\mathrm{Fe}, \mathrm{FeO})}$. We know that according to Ellingham diagram, compound having lower $\Delta_f G^s$ undergo its formation. Hence, coke can reduce FeO to Fe .