Answer to Question #205196 in Chemistry for Ankush

Question

The equation for the decomposition of mercury(II) oxide is as follows. Determine Heat of formation for HgO(s)?

2HgO(s)+182KJ=2Hg(l)+O2(g)

Answer 1

$2HgO(s)+182KJ=2Hg(l)+O2(g)$

So,

heat of the reaction, ∆H_rxn = +182Kj

The heart of the reaction will be

∆H_rxn =2×heat of formation of Hg(l) + heat of formation of O2(g) – (heat of formation of HgO×2)

Or, 182 Kj =2×∆H_f(Hg) + ∆H_f(O2) – ∆H_f(HgO)

Since, heat of formation of elements is zero,

So, ∆H_f(HgO) = 0 kj/mol and ∆H_f(O2) = 0 kj/mol

So, 182 Kj = 2×0 + 0 – ∆Hf(HgO)

Or, ∆Hf(HgO) = –182 Kj

So, heat of formation of HgO = –182 Kj/mol