Does the critical temperature of a gas depend on the amount of the gas taken? Or is it independent of it? My book does not specify this point.

I think according to the gas laws, the critical temperature should depend on the amount of gas taken. Am I correct?

  • 3
    $\begingroup$ Critical parameters are intensive properties, independent on the system scaling. $\endgroup$
    – Poutnik
    Commented May 26, 2021 at 6:12

1 Answer 1


I don’t think you're correct. The critical values (pressure, volume and temperature) are the properties of a gas and they don’t depend on how many moles of the gas you have. It's also evident from the formula of critical temperature:

$$T_\mathrm{c} = \frac{8a}{27Rb},$$

where $a,$ $b$ and $R$ are constant for the gas. There is no dependency on the amount of substance.

Further, you don’t find any data on the amount of a gas when you look for the value of it’s critical temperature. For example in table 3.10 here.

  • $\begingroup$ Critical volume is defined for one mole of the gas at critical temperature, but it's formula is : $3b$. So I am not sure we can base our arguments on these formulae. $\endgroup$ Commented May 26, 2021 at 4:23
  • $\begingroup$ I’m not completely sure but I think critical volume is defined for 1 mol because volume increases with an increase in no. of moles of the gas whereas temperature doesn’t. So we need to define critical volume for a certain quantity, i.e. 1 mol, but the same doesn’t apply on critical temperature. But again, this is my hypothesis which I haven’t cross checked anywhere. $\endgroup$
    – WhySee
    Commented May 26, 2021 at 4:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.