Which of the following processes is/are exothermic?(1) I2(l) ⟶⟶ I2(s)(2) Cl(g) + e− ⟶⟶ Cl−(g)(3) Na(g) ⟶⟶ Na+(g) + e−(4) H(g) + Cl(g) ⟶⟶ HCl(g) (1), (2), and (3) (4) only (2) and (4) (1) and (3) (1), (2) and (4)
Question
Which of the following processes is/are exothermic?(1) I2(l) ⟶⟶ I2(s)(2) Cl(g) + e− ⟶⟶ Cl−(g)(3) Na(g) ⟶⟶ Na+(g) + e−(4) H(g) + Cl(g) ⟶⟶ HCl(g) (1), (2), and (3) (4) only (2) and (4) (1) and (3) (1), (2) and (4)
Solution
The question is asking which of the given processes are exothermic.
Exothermic reactions are those that release heat to the surroundings. This means that the energy of the products is less than the energy of the reactants.
Let's analyze each process:
(1) I2(l) ⟶⟶ I2(s): This is a phase transition from liquid to solid. This process is exothermic because when a substance changes from a liquid to a solid, it releases heat.
(2) Cl(g) + e− ⟶⟶ Cl−(g): This is an electron gain process. It is exothermic because energy is released when an electron is added to an atom to form an anion.
(3) Na(g) ⟶⟶ Na+(g) + e−: This is an ionization process. It is endothermic because energy is required to remove an electron from an atom to form a cation.
(4) H(g) + Cl(g) ⟶⟶ HCl(g): This is a chemical reaction forming a compound. It is exothermic because energy is released when new bonds are formed in the products.
So, the exothermic processes are (1), (2), and (4).
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