Which of the following reactions absorbs heat from the surroundings in order to proceed to completion?
I. CO (g) + ¹/₂ O₂ (g) →CO₂ (g) D H _rxn = - 283.0 kJ
II. Al₂O₃ (s) →2 Al (s) + ³/₂ O₂ (g) (endothermic)
III. SO₃ (g) + 99.2 kJ→S (s) + ³/₂ O₂ (g)

Question

Quizplus · Accepted Answer

Reactions that absorb heat from the surroundings are endothermic. Both II and III are described as requiring energy input (II is explicitly stated as endothermic, and III shows heat being absorbed as part of the reaction). Reaction I is exothermic, as indicated by a negative ΔH.

Which of the Following Reactions Absorbs Heat from the Surroundings