Entropy and spontaneity

In which reaction will there be a decrease in entropy? A. $\ce{NH4NO3(s) -> NH4NO3(aq)}$ B. $\ce{CaCO3(s) -> CaO(s) + CO2(g)}$ C. $\ce{2H2(g) + O2(g) -> 2H2O(l)}$ D. $\ce{Zn(s) + CuSO4(aq) -> ZnSO4(aq) + Cu(s)}$

(i) Calculate, in $\mathrm{kJ\,mol^{-1}}$, the standard enthalpy change of this hydrogenation reaction using the enthalpy of combustion data in section 14 of the data booklet. (ii) The standard entropy change for this reaction is…

Which change results in a decrease in entropy? A. $\ce{2NaHCO3(s) -> Na2CO3(s) + H2O(g) + CO2(g)}$ B. $\ce{I2(s) -> I2(g)}$ C. $\ce{CO(g) + 2H2(g) -> CH3OH(l)}$ D. $\ce{KNO3(s) -> KNO3(aq)}$

Which condition applies to a reaction mixture that has reached equilibrium at constant temperature and pressure? A. $\Delta H = 0$ B. $\Delta G = 0$ C. $K = 1$ D. $\Delta S_\text{system} = 0$

For which of these changes is $\Delta S$ negative? A. $\ce{2SO2(g) + O2(g) -> 2SO3(g)}$ B. $\ce{NaNO3(s) -> NaNO3(aq)}$ C. $\ce{Zn(s) + 2HCl(aq) -> ZnCl2(aq) + H2(g)}$ D. $\ce{CuCO3(s) -> CuO(s) + CO2(g)}$

A reaction is spontaneous at low temperatures but becomes non-spontaneous when the temperature is raised. Which combination of signs of $\Delta H$ and $\Delta S$ is consistent with this behaviour? A. $\Delta H > 0$ and $\Delta S > 0$ B. $\Delta H < 0$ and…

Which reaction has the largest positive entropy change? A. $\ce{2SO2(g) + O2(g) -> 2SO3(g)}$ B. $\ce{NH4Cl(s) -> NH3(g) + HCl(g)}$ C. $\ce{H2(g) + Cl2(g) -> 2HCl(g)}$ D. $\ce{NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(l)}$

(i) Calculate the enthalpy change, $\Delta H$, for the overall synthesis of propyl ethanoate from propane and ethane shown above. Use section 12 of the data booklet. (ii) Two students each calculated the enthalpy change for the reaction between propan-1-ol and…

(i) Using section 12 of the data booklet, determine the standard enthalpy change of the reaction, in $\mathrm{kJ\,mol^{-1}}$. (ii) A value obtained from bond enthalpies is less accurate than one obtained from enthalpies of formation. State two reasons why.…

Which reaction is expected to have the largest decrease in entropy? A. $\ce{2H2S(g) + SO2(g) -> 3S(s) + 2H2O(l)}$ B. $\ce{2C4H10(g) + 13O2(g) -> 8CO2(g) + 10H2O(l)}$ C. $\ce{4NH3(g) + 5O2(g) -> 4NO(g) + 6H2O(g)}$ D. $\ce{2CO(g) + O2(g) -> 2CO2(g)}$