For a real gas (mol. mass = 60 ),if density at critical point is 0.80 $\frac{g}{c m^{3}}$ and its $T_{c} = \frac{4 \times 10^{5}}{821} K$ .Find the Van der Waals constant “a”(in $a t m L^{2} m o l^{- 2}$ ) .

For one mole of a Van der Waals gas when b = 0 and T = 300 K, then pV vs. $\frac{1}{V}$ plot is shown in figure. The value of the Van der Waals constant "a" $(a t m L^{2} m o l^{- 2}$ )is___.

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For carbon dioxide, critical density is 0.55 g/cc and its Tc=300 K. What is the value of Van der Waals' constant a (in atmL2mol−2)? (Use R=0.08LatmK−1 mol−1)

The correct option is B 0.81Using formula, PcM=ρcRTc ⇒a27b2×44=0.55×R×8a27Rb ⇒b=440.55×8=10 cm3 mol−1 Also, Tc=8a27Rb=300 K ⇒a=300×27×0.08×0.018 ⇒a=0.81 atm L2mol−2

For carbon dioxide, critical density is 0.55 g/cc and its $T_{c} = 300 K$ . What is the value of Van der Waals' constant $a$ (in $a t m L^{2} m o l^{- 2}$ )?
(Use $R = 0.08 L a t m K^{- 1} m o l^{- 1}$ )