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) $\rightarrow$ H₂O₂(g) + 136 kJ
(ii) H₂(g) + O₂(g) + 136 kJ $\rightarrow$ H₂O₂(g)
(iii) H₂(g) + O₂(g) $\rightarrow$ H₂O₂(g) ?0?H = -136 kJ
(iv) H₂(g) + O₂(g) $\rightarrow$ H₂O₂(g) ?0?H = +136 kJ

Question

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)

\rightarrow

H₂O₂(g) + 136 kJ
(ii) H₂(g) + O₂(g) + 136 kJ

\rightarrow

H₂O₂(g)
(iii) H₂(g) + O₂(g)

\rightarrow

H₂O₂(g) ?0?H = -136 kJ
(iv) H₂(g) + O₂(g)

\rightarrow

H₂O₂(g) ?0?H = +136 kJ

Quizplus · Accepted Answer

The correct thermochemical equation should have the products and reactants on opposite sides of the reaction arrow and should include the correct enthalpy change. Option i has the correct placement of reactants and products but the enthalpy change is not included in the equation. Option ii has the enthalpy change included but has the products and reactants on the same side of the arrow. Option iii has the correct placement of reactants and products but the enthalpy change is labeled as ?0?H instead of -136 kJ. Option iv has the correct placement of reactants and products and the correct enthalpy change, so the best answer is i and iii.

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

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