JEE Advanced 2025 — Paper 1 — CHEM-III solution

JEE Advanced2025Paper 1CHEM-III

The monomer (X) involved in the synthesis of Nylon 6,6 gives positive carbylamine test. If 10 moles of X are analyzed using Dumas method, the amount (in grams) of nitrogen gas evolved is _______.

Use: Atomic mass of N (in amu) = 14

Your answer

Solution

Nylon 6,6 is produced from hexamethylenediamine, H $_{2}$ N–(CH $_{2}$ ) $_{6}$ –NH $_{2}$ , and adipic acid. The carbylamine test is positive only for primary amines, so the monomer X is hexamethylenediamine (the adipic acid monomer has no –NH $_{2}$ ).

Hexamethylenediamine has the formula C $_{6}$ H $_{16}$ N $_{2}$ , containing two N atoms per molecule.

In the Dumas method, all nitrogen in the organic compound is converted to N $_{2}$ gas:

$C_{x} H_{y} N_{z} + (2 x + y /2) CuO \to x CO_{2} + \frac{y}{2} H_{2} O + \frac{z}{2} N_{2}$

For each mole of X (with $z = 2$ ), 1 mole of N $_{2}$ is produced.

From 10 mol of X: 10 mol of N $_{2}$ $\Rightarrow$ mass $= 10 \times 28 = 280$ g.

$∴$ Mass of N $_{2}$ evolved $= 280.00$ g.

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