Which method would most effectively break down calcium carbonate (CaCO_3) into its constituent elements?

• A. Dissolving CaCO_3 in water
• B. Heating CaCO_3 in air
• C. Mixing CaCO_3 with hydrochloric acid
• D. Electrolysis of molten CaCO_3

Answer: (D)

Verified step by step guidance

1. Understand that calcium carbonate (CaCO_3) is a compound composed of calcium (Ca), carbon (C), and oxygen (O) atoms chemically bonded together.
2. Recognize that breaking down CaCO_3 into its constituent elements means decomposing it into elemental calcium, carbon, and oxygen, which requires breaking strong chemical bonds.
3. Evaluate the given methods: dissolving in water only causes physical dispersion without breaking chemical bonds; heating in air typically causes thermal decomposition to calcium oxide (CaO) and carbon dioxide (CO_2), not elemental breakdown; mixing with hydrochloric acid results in a chemical reaction producing calcium chloride, water, and carbon dioxide, but not elemental calcium or carbon.
4. Understand that electrolysis involves passing an electric current through a molten (liquid) ionic compound to break it down into its elemental components by reducing and oxidizing ions at electrodes.
5. Conclude that electrolysis of molten CaCO_3 is the most effective method to break it down into elemental calcium, carbon, and oxygen because it provides the energy needed to separate the ions into their elemental forms.