Complete the table by putting one tick (✓) in every row to show the sign of each energy change under standard conditions.
Explain the meaning of the term enthalpy change of atomisation.
The overall equation for the atomisation of liquid bromine molecules, $\text{Br}_2(l)$, is shown. $\text{Br}_2(l) \rightarrow 2\text{Br}(g)$ This takes place in two steps. Draw a labelled energy cycle to show this atomisation process, with state symbols included. Using your cycle and the relevant data from the Data Booklet, work out the enthalpy change of vaporisation of $\text{Br}_2(l)$, $\Delta H^\circ_{\text{vap}}$. The enthalpy change of atomisation of bromine, $\Delta H^\circ_{\text{at}}$, $= +112\ \text{kJ mol}^{-1}$.
Suggest how the $\Delta H^\circ_{\text{vap}}$ of iodine, $\text{I}_2(l)$, would compare with that of bromine, $\text{Br}_2(l)$. Give your reason.
Explain the meaning of the term enthalpy change of hydration.
Suggest why the enthalpy change of hydration of $\text{Br}^-(g)$ is more exothermic than that of $\text{I}^-(g)$.