Final answer:
Calcium cannot be extracted from calcium chloride with carbon because this reduction process is not energetically sensible; CaCl2 is a stable compound and carbon doesn't provide sufficient reduction potential to make this reaction spontaneous under standard conditions.
Step-by-step explanation:
Calcium cannot be extracted by heating calcium chloride with carbon because this process is not thermodynamically favorable under standard conditions. Heating calcium carbonate (CaCO3) leads to the endothermic reaction of calcium carbonate decomposition into calcium oxide (CaO) and carbon dioxide (CO2), which requires an absorption of energy to occur. Meanwhile, in the context of a typical non-transition metal like calcium, the formation of CaCl2 rather than any other compound such as CaCl or CaCl3 is due to energetics; CaCl2 is very exothermic to form, making it more stable.
To extract calcium from calcium chloride using carbon, you would ideally be relying on a redox reaction where carbon would reduce the calcium ions to metallic calcium. However, this reaction is not energetically sensible for calcium since its compounds are stable and the carbon cannot provide enough reduction potential to overcome the energy needed for electron transfer.
For the chemical reaction where calcium chloride reacts with carbonic acid to produce calcium carbonate, the reaction requires a precise stoichiometry to determine the amount of calcium chloride needed to produce a certain amount of calcium carbonate, adhering to the law of conservation of mass.