When one mole of gaseous hydrogen peroxide,H₂O₂,is made from hydrogen and oxygen gases,the enthalpy change is -136 kJ.Which of the following correctly represents the thermochemical equation?
i.H₂(g) + O₂(g) → H₂O₂(g) + 136 kJ
ii.H₂(g) + O₂(g) + 136 kJ → H₂O₂(g)
iii.H₂(g) + O₂(g) → H₂O₂(g) ΔH = -136 kJ
iv.H₂(g) + O₂(g) → H₂O₂(g) ΔH = +136 kJ

Question

Quizplus · Accepted Answer

Thermochemical equations include the enthalpy change (ΔH) as a component of the equation, either on the product or reactant side. Option i correctly includes the enthalpy change on the product side, while option iii correctly includes the enthalpy change as ΔH. Therefore, i and iii are both correct representations of the thermochemical equation. Option ii places the enthalpy change on the reactant side, which is incorrect. Option iv has the wrong sign for the enthalpy change, as it should be negative (exothermic) instead of positive (endothermic). So, the correct choices are i and iii, which are both included in option D.

When One Mole of Gaseous Hydrogen Peroxide,H2O2,is Made from Hydrogen

When One Mole of Gaseous Hydrogen Peroxide,H₂O₂,is Made from Hydrogen