Calculate DH° for the reaction C4H4(g) + 2H2(g) C4H8(g), using the following data:?

Question

Calculate DH° for the reaction C4H4(g) + 2H2(g) C4H8(g), using the following data:

DH°combustion for C4H4(g) = -2341 kJ/mol

DH°combustion for H2(g) = -286 kJ/mol

DH°combustion for C4H8(g) = -2755 kJ/mol

Answer 1

1) What you are asking is the Heat of reaction for this process.

DH° = Sum(nDHprod) - Sum(n*DHreact)

where : Sum = summation; n=number of moles

2) Substituting values:

DH° = Sum(-2755 kJ/mol) - Sum (-2341+ (2)x(-286 kJ/mol))
DH° = -2755 kJ/mol - Sum(-2913 kJ/mol)
DH° = -2755 kJ/mol + 2913 kJ/mol
DH° = 158 kJ/mol

3) Finally:

DH° = 158 kJ/mol

That´s it!

Good luck!