C₁₇H₃₅COOH (Stearic acid) + NaOH (Sodium hydroxide) → C₁₇H₃₅COONa (Sodium stearate) + H₂O (Water)
Here's a breakdown:
* Stearic acid (C₁₇H₃₅COOH): This is a long-chain fatty acid that is the primary component of many fats and oils.
* Sodium hydroxide (NaOH): This is a strong base that is commonly used in soap making.
* Sodium stearate (C₁₇H₃₅COONa): This is the soap molecule. The sodium ion (Na⁺) forms an ionic bond with the carboxylate group (-COO⁻) of the stearic acid molecule.
* Water (H₂O): This is a byproduct of the reaction.
Mechanism:
The reaction between stearic acid and sodium hydroxide is a saponification reaction. This is a type of hydrolysis reaction where an ester (in this case, the ester linkage in stearic acid) is broken down by a strong base.
1. Hydroxide ions (OH⁻) from NaOH attack the carbonyl group (C=O) of the stearic acid molecule.
2. The ester bond breaks, forming a carboxylate ion (RCOO⁻) and water.
3. The carboxylate ion then reacts with a sodium ion (Na⁺) to form sodium stearate, the soap molecule.
Note:
* This is a simplified equation. In reality, the reaction is more complex and involves multiple steps.
* The reaction is typically carried out in a hot solution, and often involves other fats or oils in addition to stearic acid.
* The soap molecule has a polar (hydrophilic) head (the carboxylate group) and a non-polar (hydrophobic) tail (the long hydrocarbon chain). This structure allows soap to act as a surfactant, which means it can lower the surface tension of water and help to emulsify dirt and grease.
