Q30 / 90 · JEE Main 2021 (27 Aug Shift 1) · Chemistry

The number of moles of $CuO,$ that will be utilized in Dumas method for estimating nitrogen in a sample of $57.5 g$ of $N, N -$ dimethylaminopentane is ________ $\times 10^{- 2} .$ (Nearest integer)

Correct answer: 1125

Solution

Moles of $N$ N in $N, N$ -dimethylaminopentane $= \frac{57.5}{115} = 0.5$ mol

$C_{7} H_{17} N + \frac{45}{2} CuO ⟶ 7 {CO}_{2} + \frac{17}{2} H_{2} O + \frac{1}{2} N_{2} + \frac{45}{2} Cu$

$\frac{no. molesof CuO reacted}{45 / 2} = \frac{no. molesof C_{7} H_{17} N reacted}{1}$

$∴$ no. of moles of $CuO$ reacted $= \frac{45}{2} \times 0.5 = 11.25 = 1125 \times 10^{- 2}$

Hence, the correct answer is 1125.