Write balanced chemical equation for the standard formation reaction of solid magnesium bromide

 

for delta Horxn to be delta Hof,

rule 1: there must be only 1 mol of product being formed

rule 2: reactant must be element in there standard state

So, 1 mol of MgBr2 (s) will form.

standard state of Br is Br2 in liquid state.

So, 1 reactant is Br2(l).

standard state of Mg is Mg(s).

so, other reactant is Mg(s).

So, the equation is:

Mg (s) + Br₂ (l) -> MgBr₂ (s)