The equation for the formation of octane from its elements is:

8C(s) + 9H₂(g) → C₈H₁₈(l)

Here's a breakdown of the equation:

* 8C(s): This represents 8 moles of solid carbon (C)

* 9H₂(g): This represents 9 moles of hydrogen gas (H₂)

* C₈H₁₈(l): This represents 1 mole of liquid octane (C₈H₁₈)

This equation shows that 8 moles of carbon and 9 moles of hydrogen gas react to produce 1 mole of octane.