Zadania z chemii IB HL

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. $\ce{KNO3(s) -> KNO3(aq)}$

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. $\ce{CuCO3(s) -> CuO(s) + CO2(g)}$

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) 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. $\ce{2CO(g) + O2(g) -> 2CO2(g)}$

Pentadecane can be cracked into smaller molecules. Consider the reaction: $\ce{C15H32(g) -> 3C4H8(g) + C3H8(g)}$ where $\ce{C4H8}$ is but-1-ene. (i) Use the bond enthalpies in section 12 of the data booklet to determine $\Delta H^\ominus$ for this reaction.…