Lawrie Ryan and Roger Norris Solutions for Chapter: Enthalpy Changes, Exercise 1: BEFORE YOU START

Make a list of reactions that are definitely exothermic and another list of reactions that you know are endothermic. Explain to another learner how you know that these reactions are either exothermic or endothermic.

Explain the reaction pathway diagram (energy profile diagram) for an endothermic reaction.

Take it in turns to explain these terms to another learner: bond energy; enthalpy change; activation energy; standard conditions.

Write the displayed formulae (structures showing all atoms and all bonds) of the following: ${\mathrm{CO}}_2, {\mathrm{H}}_2\mathrm{O}, {\mathrm{C}}_2{\mathrm{H}}_6, {\mathrm{NH}}_3, {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$.

Work with another learner to describe how to calculate the energy change in the reaction ${\mathrm{C}}_2{\mathrm{H}}_4+3{\mathrm{O}}_2\to 2{\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$ by using bond energies.

$$\begin{gathered} \mathrm{E}\left(\mathrm{C}-\mathrm{H}\right)=+412 \mathrm{kJ} {\mathrm{mol}}^{-1}. \\ \mathrm{E}\left(\mathrm{O}=\mathrm{O}\right)=+496 \mathrm{kJ} {\mathrm{mol}}^{-1}. \\ \mathrm{E}\left(\mathrm{C}=\mathrm{O}\right)=+805 \mathrm{kJ} {\mathrm{mol}}^{-1}. \\ \mathrm{E}\left(\mathrm{C}=\mathrm{C}\right)=+600 \mathrm{kJ} {\mathrm{mol}}^{-1}. \\ \mathrm{E}\left(\mathrm{O}-\mathrm{H}\right)=+463 \mathrm{kJ} {\mathrm{mol}}^{-1}. \end{gathered}$$