All of the following chemical reactions are endothermic except
Correct answer: C. H2O(g) → H2O(l)
- A. H2O(s) → H2O(l)
- B. 2H2O(g) → 2H2(g) + O2(g)
- C. H2O(g) → H2O(l)
- D. Al2O3(l) + 2Fe(l) → 2Al(s) + Fe2O3(s)
Explanation
An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in an increase in the internal energy of the system. Therefore, the products have more internal energy than the reactants.The phase transition from a gas to a liquid is an exothermic process. The molecules or atoms in the gas phase have sufficient kinetic energy to have overcome the attractive forces between the molecules or atoms.
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About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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