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$$\ce{SiO2 + 2C ->[2200°C] Si + 2CO}$$(Ref)

In this reaction, C is apparently displacing Si from SiO2. Does this mean C is more reactive than Si? But Si is more electropositive than C. What is the explanation for this? Where will Si be placed in the reactivity series?

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    $\begingroup$ It depends. What temperature? $\endgroup$ – MaxW Jan 13 at 3:57
  • $\begingroup$ @MaxW I made the changes $\endgroup$ – Shub Jan 13 at 4:00
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    $\begingroup$ Reactivity is not a thing at all. Also, CO2 does not form in your reaction, nor does your reference say so. $\endgroup$ – Ivan Neretin Jan 13 at 6:10
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Let's compare the boiling points of these substances. Silicon is boiling at $2355°$C. Carbon is boiling at $4200°$C. $\ce{SiO2}$ is boiling at $2590°$C. So at $2200°$C, $\ce{CO}$ is the only gaseous substance. Whatever the change of enthalpies or the electronegativities, its formation is favored.

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That is not a reaction that happens. That is a summary of a set of reactions that happen, at (at least 2) different equilibria and different temperatures.

The direct reactions are as follows, at "steady state" solids if not specified:

$$\ce{2SiO_2 + SiC <-> 3SiO(g) + CO(g)}$$ $$\ce{SiO_2 + Si(l) <-> 2SiO(g)}$$ $$\ce{SiO(g) + SiC <-> Si(l) + CO(g)}$$ $$\ce{SiO(g) + 2C <-> SiC + CO(g)}$$

There is no reasonable answer to your question, because that reaction does not happen in a single step, it is not displacing anything. Though, the fact that you have to pour a spectacular number megawatts into the process for it to continue does suggest that $\ce{Si}$ is not "more reactive" though.

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