.2g of nitrous oxide (N₂O) gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1mL to 167.75mL. The change in thermal energy of the process, $Δ U$ is ‘-x’ J. The value of ‘x’ is________. [Nearest Integer]

(Given : atomic mass of N = 14 g mol^-1 and of O = 16 g mol^-1.

Molar heat capacity of N₂O is 100 J K^-1 mol^-1)

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alok kumar singh | Contributor-Level 10

3 weeks ago

Moles of N₂O = $\frac{2.2}{44} = \frac{1}{20}$

$Δ H = n C_{p} Δ T = \frac{1}{20} \times 100 (- 40) = - 200 J$

$Δ U = q_{p} + w$

$w = - P_{e x t} . Δ V$

$w = - 1 \frac{(167.75 - 217.1)}{1000} \times 101.3 J = + 5 J$

$Δ U = - 200 + 5 = 195 J$

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