Q.Nylon-6,6 is formed from hexamethylenediamine and adipic acid.

At each step where an $-\text{NH}_2$ of hexamethylenediamine condenses with a $-\text{COOH}$ of adipic acid to form the amide linkage, one molecule of water is eliminated as the by-product. The name 'nylon-6,6' records the carbon count of each monomer: hexamethylenediamine, $\text{H}_2\text{N--}(\text{CH}_2)_6\text{--NH}_2$, has 6 carbon atoms, and adipic acid, $\text{HOOC--}(\text{CH}_2)_4\text{--COOH}$, also has 6 carbon atoms in total (the 4 $-\text{CH}_2-$ carbons plus the 2 carboxyl carbons). The two numbers, written in the order diamine-then-diacid, distinguish it from other nylons made from monomers with di …

Identify the condensation by-product from the reacting functional groups, then count the carbon atoms contributed …

Miscounting adipic acid's carbons by forgetting to include its two carboxyl carbons in the total of 6; assuming the two numbers in 'nylon-6,6' refer to something ot …