# Is it true that under certain conditions, Mg can reduce SiO2?

Is it true that under certain conditions, Mg can reduce $\ce{SiO2}$ and the latter the former? What are those conditions?

• Jan 16 '15 at 11:41
• Take a look at the link of the question you've asked. And take a look at this meta post. Jan 16 '15 at 11:42

Yes, it is true below $$\pu{1683 K}$$, the melting point of silicon, the $$\Delta_\mathrm{f}G^\circ$$ curve for the formation of $$\ce{SiO2}$$ lies above the $$\Delta_\mathrm{f}G^\circ$$ curve for $$\ce{MgO}$$, so, at temperature below $$\pu{1683 K}$$, $$\ce{Mg}$$ can reduce $$\ce{SiO2}$$ to $$\ce{Si}$$.
On other hand, above $$\pu{1683 K}$$ the $$\Delta_\mathrm{r}G^\circ$$ curve for $$\ce{MgO}$$ lies above for $$\ce{SiO2}$$, hence at temperatures above $$\pu{1683 K}$$, $$\ce{Si}$$ can reduce $$\ce{MgO}$$ to $$\ce{Mg}.$$