Sand is converted to pure silicon in a three step process. the third step issicl4(g) + 2mg(s) ? 2mgcl2(s) + si(s) ? h = -625.6 kjwhat is the enthalpy change when 12.5 mol of silicon tetrachloride is converted to elemental silicon? a 12.5 kjb 3910 kjc 0.78 x 10^4 kjd 1.56 x 10^4 kj

(C) 0.78×10⁴ kJ

Explanation:

The enthalpy of the reaction = -625.6 kJ (Negative sign signifies heat released).

From the reaction,

1 mole of silicon tetrachloride undergoes reaction to produce 1 mole of elemental silicon with the release of energy 625.6 kJ

So,

For 12.5 moles of silicon tetrachloride:

The enthalpy is : -625.6 *12.5 kJ = 7820 kJ.

Rearranging in the form of answer as 7820 kJ = 0.78×10⁴ kJ (C)

a electronegativity decreases beacuse the size of nucleus is bigger.