Which of the following is an exothermic reaction?
Correct answer: A. H+(aq) + OH−(aq) -> H2O(l)
- A. H+(aq) + OH−(aq) -> H2O(l)
- B. 1/2 H2(g) -> H(g)
- C. Na(g) -> Na+(g) + 1e−
- D. 1/2 Cl2(g) -> Cl(g)
Explanation
Explanation:Neutralization is always an exothermic reaction. Hence, the correct answer is A. These options are incorrect because they are atomization reactions and involve the breaking of bonds. This option is not correct because it is an Ionization reaction and involves the removal of electrons from the valence shell.
This question appeared on the UHS MDCAT 2009 paper, which you can sit online with every answer explained.
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About Exothermic and Endothermic Reactions
Exothermic reactions release heat to the surroundings and have negative enthalpy change, while endothermic reactions absorb heat and have positive enthalpy change. The topic uses energy profiles to identify reactants, products and activation energy, and includes bond energy, enthalpy diagrams, calorimetry and Hess's law for calculating overall heat changes.
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