Which of the following is described by the equation [tex]H_2O (l) \rightarrow H_2O (s) + \text{heat}[/tex]?

A. Melting
B. Condensing
C. Freezing
D. Evaporating



Answer :

To understand the process described by the equation [tex]\(H_2O (\Lambda) \rightarrow H_2O (s) + \text{heat}\)[/tex], let's break down and explain each part of the chemical equation step by step:

1. Chemical Equation:
The reactant is [tex]\(H_2O (\Lambda)\)[/tex], which denotes liquid water.

2. Products:
On the product side, we have [tex]\(H_2O (s)\)[/tex], which denotes solid water (ice), and heat is released.

3. Nature of the Process:
- The equation shows liquid water turning into solid water (ice).
- Since heat is being released (exothermic process), this implies the release of thermal energy as the substance transitions from a higher-energy state (liquid) to a lower-energy state (solid).

Based on this description, let’s evaluate the options:

A. Melting:
- Melting involves a solid turning into a liquid. It typically requires the absorption of heat.
- Equation for melting: [tex]\(H_2O (s) \rightarrow H_2O (\Lambda) + \text{heat absorbed}\)[/tex].
- This does not match our equation.

B. Condensing:
- Condensation involves a gas turning into a liquid. It usually releases heat.
- Equation for condensation: [tex]\(H_2O (g) \rightarrow H_2O (\Lambda) + \text{heat released}\)[/tex].
- This does not match our equation either.

C. Freezing:
- Freezing involves a liquid turning into a solid. It releases heat.
- Equation for freezing: [tex]\(H_2O (\Lambda) \rightarrow H_2O (s) + \text{heat released}\)[/tex].
- This matches our equation.

D. Evaporating:
- Evaporation involves a liquid turning into a gas. It requires the absorption of heat.
- Equation for evaporation: [tex]\(H_2O (\Lambda) \rightarrow H_2O (g) + \text{heat absorbed}\)[/tex].
- This does not match our equation.

By analyzing the process and the chemical equation provided, we determine that the process described is freezing.

Therefore, the correct answer is:
C. Freezing