Q.Following type of non-ionic detergents are present in liquid detergents, emulsifying agents and wetting agents. Label the hydrophilic and hydrophobic parts in the molecule. Identify the functional group(s) present in the molecule.
C9H19-C6H4-O(CH2CH2O)xCH2CH2OH (x = 5 to 10)

In a detergent molecule, the hydrophobic (water-repelling) part is a non-polar hydrocarbon portion with no affinity for water, while the hydrophilic (water-attracting) part is polar and can hydrogen-bond with water.

For $C_9H_{19}-C_6H_4-O(CH_2CH_2O)_xCH_2CH_2OH$:

• Hydrophobic part: $C_9H_{19}-C_6H_4-$ — a nonyl (C9) hydrocarbon chain attached to a benzene ring. Being a hydrocarbon/aromatic group, it is non-polar and water-insoluble.
• Hydrophilic part: $-O(CH_2CH_2O)_xCH_2CH_2OH$ — the repeating polyethylene oxide chain terminating in a free $-OH$ group. The several ether oxygens along the chain and the terminal hydroxyl group can form hydrogen bonds with water, making this part water-soluble.
• Functional groups present: ether linkages ($-O-$, repeated x+1 times within the chain) and one terminal alcohol ($-OH$) group. …

Split the molecule into a non-polar hydrocarbon/aromatic segment (hydrophobic) and a polar, H-bonding-capable segment (hydrophilic). Identify the repeating $ …

• Calling the molecule ionic because it contains several oxygen atoms — the ether/–OH groups make it polar but it carries no net charge, so it is non-ionic. …