CH₃CH₂COO^– Na⁺ $\stackrel{NaOH,+?}{\underset{Heat}{⟶<!--\; ⟶\; -->}}$ CH₃CH₃ + Na₂CO₃. Consider the above reaction and identify the missing reagent/chemical.

The reaction shown starts with the sodium salt of propionic acid, CH3CH2COO– Na+. When this compound is heated, it undergoes a decarboxylation reaction that removes the carboxylate group as carbon dioxide, producing an alkane.

In the classic thermal decarboxylation of a sodium carboxylate, a solid oxide such as quicklime (CaO) is added. CaO serves two important roles:

• It acts as a basic catalyst that abstracts a proton from the α‑carbon, facilitating formation of a radical intermediate.
• It captures the generated carbon dioxide by forming sodium carbonate (Na2CO3), driving the reaction forward.

The overall balanced transformation is:

Thus, the missing reagent that enables the conversion of CH3CH2COO– Na+ into ethane (CH3CH3) and the by‑products NaOH and Na2CO3 is calcium oxide (CaO).