Question

Is the sodium salt of propanoic acid as effective as soap as sodium stearate? Explain.

Short answer

No, the sodium salt of propanoic acid is not as effective as soap as sodium stearate.

Step-by-step solution

Definition of intermolecular force

Soap is chemically a sodium or potassium salt of long-chain carboxylic acids. Here, propanoic acid has three carbon units whereas stearic acid has eighteen carbon units.

Explanation

The hydrocarbon tail of sodium stearate is much longer than sodium propanoate. So, the interaction of the former with any oily or greasy material would be more flexible due to strong dispersion force than the latter. Therefore, although both have some kind of nonpolar interaction with the water molecules, sodium stearate is more effective as a soap than sodium propanoate.