Question

4. Use the information below to calculate the standard enthalpies of formation of

(a) KClO3(s) from the tabulated value of the enthalpy of formation of KCl,

(b) NaHCO3(s) from the tabulated value of the enthalpies of formation of CO2 and NaOH.

2KClO3(s) → 2KCl(s) + 3O2(g) ΔrHo = -111.4 kJ/mol

NaOH(s) + CO2(g) → NaHCO3(s) ΔrHo = -150.5 kJ/mol

I think I understand how to do this but I'm confused by the wording in this question.


what is:
\[\Delta_r H ^{o}\]
???

I assume I use the formula I posted bellow but yeah just confused by this question.

I know the enthalpy of formation for oxygen is 0, so where do I go from there do I use the formula below?