Terylene forms by esterification of ethylene glycol (HOCH2CH2OH) with terephthalic acid (benzene-1,4-dicarboxylic acid, HOOC-C6H4-COOH). Taking C = 12, H = 1, O = 16 and ignoring end groups, the molar mass of one repeat unit in g mol^-1 is

JEE Advanced levelSingle correct optionDifficulty 3 of 3pl008

Terylene forms by esterification of ethylene glycol ( $HOCH X_{2} CH X_{2} OH$ ) with terephthalic acid (benzene-1,4-dicarboxylic acid, $HOOC - C X_{6} H X_{4} - COOH$ ). Taking C = 12, H = 1, O = 16 and ignoring end groups, the molar mass of one repeat unit in $g mo l^{- 1}$ is

Molar masses: glycol

62

, terephthalic acid

166

. One repeat unit uses one of each and two ester bonds are formed, so two

H X_{2} O

(

36

) are lost:

62 + 166 - 36 = 192