Question

The hydrophilic part of \( CH_3(CH_2)_{16}COO^{-}Na^{+} \) is:

• A. \( COO^{-} \)
• B. \( CH_3(CH_2)_{16}^{-} \)
• C. \( Na^{+} \)
• D. \( CH_3^{-} \)

Hint:

When identifying the hydrophilic portion of a molecule, look for polar or charged groups, such as carboxylate (\( COO^{-} \)) or hydroxyl groups, which can form hydrogen bonds with water.

Answer 1

The Correct Option is A

In the compound \( CH_3(CH_2)_{16}COO^{-}Na^{+} \), the hydrophilic part refers to the part that is attracted to water, typically involving a polar or ionic group.
- The \( COO^{-} \) group is a carboxylate anion that is polar and hydrophilic, meaning it is water-soluble. This part of the molecule is attracted to water molecules due to the negative charge and its polarity.
- The \( Na^{+} \) cation is an inorganic ion that does not participate in hydrophilic interactions but in ionic bonding.
- The \( CH_3(CH_2)_{16} \) alkyl group is hydrophobic due to its nonpolar nature, making it repelled by water.
Thus, the hydrophilic part of this molecule is the \( COO^{-} \) group, as it is the most polar and interacts effectively with water molecules.