- #1

warhammer

- 151

- 31

- Homework Statement
- Calculate the critical temperature for a gas obeying van der Waals equation of state. Given a = 0.00874 atm cm^6 and b = 0.0023 cm³ for 1 cm³ of the gas at S.T.P.

Ans: T = 307 K

(Hint: First calculate the values of a and b for 1 mole of the gas.)

- Relevant Equations
- Critical Temperature Tc= (8a)/(27Rb)

<Using the hint, I tried to find the van der Waal constants in molar form. Since STP is mentioned, I used the unitary method relationship-

22.4 L=22400cm^3=1 molar V

<To find a possible conversion standard between cm^3 and mol; which turned out to be 1cm^3= 4.46*10^-5 mol.

<Then I used the above attained value and used them wrt 'a' & 'b', in order to convert their units from atm*cm^6 & atm*cm^3 to atm*mol^2 and atm*mol respectively.

However I'm not getting the correct answer. Please guide me where I am making the error.

(Have also attached a photo of my solution attempt)

22.4 L=22400cm^3=1 molar V

<To find a possible conversion standard between cm^3 and mol; which turned out to be 1cm^3= 4.46*10^-5 mol.

<Then I used the above attained value and used them wrt 'a' & 'b', in order to convert their units from atm*cm^6 & atm*cm^3 to atm*mol^2 and atm*mol respectively.

However I'm not getting the correct answer. Please guide me where I am making the error.

(Have also attached a photo of my solution attempt)