Given these reactions :

Question

X(s) + 1/2O2(g) --> XO(s) (Delta)H= -707.7 kj

XCO3(s) --> XO(s)+CO2(g) (Delta)H= +381.9kj

What is (delta)Hrxm for this reaction?

X(s)+1/2 O2(g)+CO2(g) ---> XCO3(s)

(Delta)H= ?

Answer 1

Flip the equation around to make the second equation a negative-- so -707.7-381.9 will give you the answer