Calculate the standard enthalpy change of the reaction SO2(g) + H2S(g) -> 2H2O(l) + 2S(s). Given that the standard enthalpy of combustion of sulphur is -297 kJmol⁻¹ and the standard enthalpies of formation of hydrogen sulphide are -20.2 kJmol⁻¹ and -286 kJmol⁻¹ respectively.

Ili kukokotoa mabadiliko ya entalpia ya kawaida ($\Delta H^\circ$) kwa mmenyuko, tutatumia Sheria ya Hess na entalpia za uundaji za kawaida.

Mmenyuko uliotolewa ni:

Tunahitaji maadili ya entalpia ya uundaji ($\Delta H^\circ_f$) kwa kila kiwanja:

• Entalpia ya mwako ya salfa ($\text{S}(\text{s})$) ni sawa na entalpia ya uundaji ya $\text{SO}_2(\text{g})$: $\Delta H^\circ_f[\text{SO}_2(\text{g})] = -297 \text{ kJ mol}^{-1}$
• Entalpia ya uundaji ya hidrojeni salfaidi ($\text{H}_2\text{S}(\text{g})$) imetolewa: $\Delta H^\circ_f[\text{H}_2\text{S}(\text{g})] = -20 \text{ kJ mol}^{-1}$ (Tunatumia thamani ya $-20 \text{ kJ mol}^{-1}$ kama ilivyoandikwa wazi zaidi)
• Entalpia ya uundaji ya maji ($\text{H}_2\text{O}(\text{l})$) haijatolewa, kwa hivyo tunatumia thamani ya kawaida ya kitabu: $\Delta H^\circ_f[\text{H}_2\text{O}(\text{l})] = -285.8 \text{ kJ mol}^{-1}$
• Entalpia ya uundaji ya salfa katika hali yake ya kawaida ($\text{S}(\text{s})$) ni sifuri: $\Delta H^\circ_f[\text{S}(\text{s})] = 0 \text{ kJ mol}^{-1}$