State and explain whether the reaction of magnesium with hydrochloric acid will cause entropy to increase or decrease.
State and explain whether dissolving solid potassium chloride in water will cause entropy to increase or decrease.
State and explain whether steam condensing to water will cause entropy to increase or decrease.
Magnesium carbonate decomposes according to $\text{MgCO}_3(s) \rightarrow \text{MgO}(s) + \text{CO}_2(g)$, $\Delta H^{\circ} = +117\,\text{kJ mol}^{-1}$. Standard entropies are: $S^{\circ}(\text{MgCO}_3) = +65.7\,\text{J mol}^{-1}\text{K}^{-1}$, $S^{\circ}(\text{MgO}) = +26.9\,\text{J mol}^{-1}\text{K}^{-1}$, $S^{\circ}(\text{CO}_2) = +214\,\text{J mol}^{-1}\text{K}^{-1}$. Calculate $\Delta G^{\circ}$ for this reaction at $298\,\text{K}$. State a suitable sign and give your answer to three significant figures.
Explain, using $\Delta G^{\circ}$, why this reaction is more feasible at higher temperatures.
On heating, sodium hydrogencarbonate breaks down into sodium carbonate as shown: $2\text{NaHCO}_3(s) \rightarrow \text{Na}_2\text{CO}_3(s) + \text{CO}_2(g) + \text{H}_2\text{O}(g)$, $\Delta H^{\circ} = +130\,\text{kJ mol}^{-1}$, $\Delta S^{\circ} = +316\,\text{J mol}^{-1}\text{K}^{-1}$. Calculate the minimum temperature at which this reaction becomes spontaneous (feasible). Show your working.
The solubility of Group 2 sulfates falls down the Group. Explain this trend.