What does the term entropy mean?
Put one tick (✓) in each row of Table 3.1 to indicate the sign of the entropy change, $\Delta S$, for each process.
Chlorine trifluoride, $\mathrm{ClF_3}$, breaks down on heating to form its elements, as shown. Reaction 1: $\mathrm{2ClF_3(g) \rightarrow Cl_2(g) + 3F_2(g)}$. Standard entropies are listed in Table 3.2. Calculate the standard entropy change, $\Delta S^{\circ}$, in $\mathrm{J\,K^{-1}\,mol^{-1}}$, for reaction 1.
Group 2 carbonates decompose when heated. The decomposition of one Group 2 carbonate, $\mathrm{MCO_3}$, is shown in reaction 2. Reaction 2: $\mathrm{MCO_3(s) \rightarrow MO(s) + CO_2(g)}$. Predict the sign of the entropy change, $\Delta S$, for reaction 2. Explain your answer.
The Gibbs equation is given as $\Delta G^{\circ} = \Delta H^{\circ} - T\Delta S^{\circ}$. Fig. 3.1 displays values of the Gibbs free energy change, $\Delta G^{\circ}$, in $\mathrm{kJ\,mol^{-1}}$, at different temperatures, $T$, in K, for reaction 2. Assume that the $\Delta H^{\circ}$ and $\Delta S^{\circ}$ values for this reaction do not vary over this temperature range. Use the gradient and the y-axis intercept from Fig. 3.1 together with the Gibbs equation to determine: $\Delta S^{\circ}$, in $\mathrm{J\,K^{-1}\,mol^{-1}}$, for reaction 2; the minimum temperature, $T$, in K, at which the reaction is feasible; and $\Delta H^{\circ}$, in $\mathrm{kJ\,mol^{-1}}$, for reaction 2.