2.2 g of nitrous oxide ( N 2 O ) gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1 mL to 167.75 mL. The change in internal energy of the process, Δ U is ' -x prime 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 N 2 O is 100 JK -1 mol -1 )

Question

2.2 g of nitrous oxide ( N 2 O ) gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1 mL to 167.75 mL. The change in internal energy of the process, Δ U is ' -x prime 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 N 2 O is 100 JK -1 mol -1 ) (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

N 2 O moles =(2.2/44)=(1/20) Δ H = nC p Δ T =(1/20) × 100(-40)=-200 J Δ U = q p + w W =- P ext Δ V W =-1 ((167.75-217.1)/1000) × 101.3 J W =+5 J Δ U =-200+5=-195 J

N2​O moles =442.2​=201​ ΔH=nCp​ΔT=201​×100(−40)=−200J ΔU=qp​+w W=−Pext​ΔV W=−11000(167.75−217.1)​×101.3J W=+5J ΔU=−200+5=−195J

$N_{2} O$ moles $= \frac{2.2}{44} = \frac{1}{20}$
$Δ H = n C_{p} Δ T = \frac{1}{20} \times 100 (- 40) = - 200 J$
$Δ U = q_{p} + w$
$W = - P_{e x t} Δ V$
$W = - 1 \frac{( 167.75 - 217.1 )}{1000} \times 101.3 J$
$W = + 5 J$
$Δ U = - 200 + 5 = - 195 J$