Question

“The heat capacity of a solid compound is equal to the sum of the heat capacities of its constituent elements”. This statement is known as:

• A. Trouton’s rule
• B. Dulong and Petit’s law
• C. Kirchhoff’s law
• D. Neumann–Kopps rule

Hint:

Use Neumann–Kopps rule to estimate the molar heat capacity of a solid compound by summing the capacities of its constituent atoms.

Answer 1

The Correct Option is D

Step 1: Understanding the Statement
The statement implies that the molar heat capacity of a solid compound can be estimated by summing the atomic heat capacities of the individual elements that make up the compound. Step 2: Neumann–Kopps Rule
The Neumann–Kopps rule specifically states that:
\textit{"The molar heat capacity of a crystalline solid compound is approximately equal to the sum of the molar heat capacities of its constituent atoms."}
This empirical rule is useful for estimating the heat capacity of solid compounds based on elemental data. Step 3: Other Options
- (A) Trouton’s rule: Relates to the entropy of vaporization of liquids, not solids.
- (B) Dulong and Petit’s law: Estimates the molar heat capacity of individual elements (typically metals), not compounds.
- (C) Kirchhoff’s law: Concerns the temperature dependence of reaction enthalpy. Conclusion: The correct law associated with the additive heat capacities of elements in a solid compound is Neumann–Kopps rule.