# How do reactants and products participate in in chemical reaction?

Jun 18, 2018

Well, this is a question into which we can sink our teeth....

#### Explanation:

Chemical change is characterized by the formation of new substances and the making and breaking of strong chemical bonds. And we can consider this definition in (say) the combustion of ethane...

${H}_{3} C - C {H}_{3} + \frac{7}{2} {O}_{2} \rightarrow 2 C {O}_{2} \left(g\right) + 3 {H}_{2} O \left(l\right)$

And here we have BROKEN $1 \times C - C$ bond, AND $6 \times C - H$ bonds, and $\frac{7}{2} \times O = O$ bonds....all of which requires energy...BUT we have made $4 \times C = O$, and $6 \times H - O$ bonds....the DIFFERENCE between making and breaking bonds represents the enthalpy change of the reaction. And this COULD be approached numerically given the relevant bond enthalpy data.... Are you happy to find these data yourself?

And so is the reaction exothermic or endothermic?