Sand Is Converted to Pure Silicon in a Three Step

Multiple Choice

Sand is converted to pure silicon in a three step process. The third step is SiCl₄(g) + 2Mg(s) → 2MgCl₂(s) + Si(s) ΔH = −625.6 kJ
What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

A) −25.0 kJ
B) −7820 kJ
C) −1.56 × 10 ⁴ kJ
D) −3.13 × 10 ⁴ kJ
E) None of these choices are correct.