Question

Which of the following compounds is thermodynamically the most stable?

• A. BaCO\(_3\)
• B. MgCO\(_3\)
• C. SrCO\(_3\)
• D. CaCO\(_3\)

Hint:

The thermodynamic stability of metal carbonates generally increases as the size of the cation increases (i.e., moving down the group in the periodic table).

Answer 1

The Correct Option is A

Thermodynamic stability of a compound is determined by its formation energy and the lattice energy. Among the given compounds, the lattice energy increases as the ionic radius of the metal increases. The more stable the ionic bond, the more stable the compound is. The stability of carbonates of alkaline earth metals (BaCO\(_3\), MgCO\(_3\), SrCO\(_3\), and CaCO\(_3\)) increases as we move down the group. This is because the ionic radius increases, leading to lower lattice energy and greater stability of the compound. Out of the compounds listed: - BaCO\(_3\) has the largest ionic radius for the alkaline earth metal (Ba\(^{2+}\)), resulting in the lowest lattice energy and thus the most thermodynamically stable compound. Therefore, the correct answer is \( \boxed{{A}} \), BaCO\(_3\).