Answer: -19 kJ
Step-by-step explanation:
The change in enthalpy
is mathematically expressed as the difference between the the total potential energy of products
and the potential energy of the reactants
:
![\Delta H=U_(products)-U_(reactants)](https://img.qammunity.org/2021/formulas/chemistry/middle-school/2nd8uukgqu6yg4mmvbqbedalzwrb30oq4w.png)
Where:
![U_(products)=110 kJ=110 (10)^(3)J](https://img.qammunity.org/2021/formulas/chemistry/middle-school/ywh0ow588jv66eem9kitka2ixagadqtszy.png)
![U_(reactants)=129 kJ=129 (10)^(3)J](https://img.qammunity.org/2021/formulas/chemistry/middle-school/fzo9h3dmtlsgre7plx41z49cg8h4yxxrtr.png)
Then:
![\Delta H=110 kJ-129 kJ](https://img.qammunity.org/2021/formulas/chemistry/middle-school/nsun257yhb0vrj8bhx46in69axsj755ob4.png)
The negative sign in this result means we have a negative enthalpy, hence an exothermic reaction (where heat is released).