Two reactions of iron with oxygen are shown. Fe(s) + O2(g) → FeO(s) ΔH = – 272 kJ mol–1 2 Fe(s) + O2(g) → Fe2O3(s) ΔH = – 822 kJ mol–1 What is the enthalpy change, in kJ mol–1 , for this reaction? 2 FeO(s) + O2(g) → Fe2O3(s) A +550 B –278 C –1094 D –1372 Answer= B, but how do you go about calculating the answer when multiple equations are given?
you are told the enthalpy of formation of FeO from the first equation so 2FeO would b 2 x -272. oxygen is an element so has no value. you are also told the enthalpy of formation of Fe2O3 which is -822. then just draw a normal hess cycle
you are told the enthalpy of formation of FeO from the first equation so 2FeO would b 2 x -272. oxygen is an element so has no value. you are also told the enthalpy of formation of Fe2O3 which is -822. then just draw a normal hess cycle