Question

Molecular density of $N_2$ at $1.00\, atm$ and 25°C is (assume ideal behaviour)

• A. $2.46 \times 10^{22} dm ^{-3}$
• B. $2.46 \times 10^{25} m ^{-3}$
• C. $2.40 \times 10^{19} cm ^{-3}$
• D. All of these

Answer 1

Answer: (D)

Molecular density is the number of molecular per unit volume.

Let, moles$= n $, Volume $= V\, L $

$pV = nRT $

$\frac{n}{V}=\frac{p}{R T}$

$=\frac{1 atm }{0.0821 \,atm \,mol ^{-1} K ^{-1} \times 298 \,K }$

$=\frac{1}{0.0821 \times 298} mol \,L ^{-1}$

$\frac{n N_{0}}{V}$ (molecular density) $=\frac{6.02 \times 10^{23}}{0.0281 \times 298} $

$=2.46 \times 10^{22} dm ^{-3} $

$=2.46 \times 10^{25} m ^{-3}$ or

$= 2.46 \times 10^{19}\, cm ^{-3} $