Question

3. Sulfur dioxide (SO2) can be reduced by hydrogen disulfide (H2S), producing sulfur in its elemental form and water (H2O). Using Hess’s law and the reactions below, determine the overall enthalpy for the reaction between SO2 and H2S. Make to clearly show your work.
H2 (g) + S (s) → H2S (g) ΔH = –20.6 kJ
SO2 (g) → S (s) + O2 (g) ΔH = +296.8 kJ
2H2 (g) + O2 (g) → 2H2O (g) ΔH = –285.8 kJ

Answer 1

The reaction between h2s and so2 results to h20 and elemental sulfur. The final reaction is SO2 +2H2S = 3S+ 2H2O. Using Hess law, the first equation is reversed and multiplied by 2, the second and the third equation remains the same. Calculating the overall enthalpy, the answer is 52.2 kJ.