Consider the intermediate equations: 3 equations. 1: upper c solid plus upper o subscript 2 gas right arrow upper c upper o subscript 2 gas delta h 1 equals negative 393.5 kilojoules. 2: 2 upper c upper o gas plus upper o subscript 2 gas right arrow 2 upper c upper o subscript 2 gas delta h 2 equals negative 566.0 kilojoules. 3: 2 upper h subscript 2 upper o gas right arrow 2 upper h subscript 2 gas plus upper o subscript 2 gas delta h 3 equals 483.6 kilojoules. with the overall reaction: upper c (s) plus upper h subscript 2 upper o (g) right arrow upper c upper o (g) plus upper h subscript 2 (g). what must be done to calculate the enthalpy of reaction? check all that apply. the first equation must be halved. the first equation must be reversed. the second equation must be halved. the second equation must be reversed. the third equation must be halved. the third equation must be reversed. what is the overall enthalpy of reaction? delta.hrxn = kj