[Win,odd Dhamnekar]

Question 1) The critical temperature for  water is 647.1 K. At [itex]10^3[/itex] bar and 700 K, the density of supercritical water is [itex]651.37 kg m^3[/itex]. Note that this is about 68% of the value for liquid water at the boiling point at 1 bar. What is the molar volume in [itex]m^3mol^{-1}[/itex] of water at this temperature and pressure? in L/mol?

Question 2)
Refer to your results in the question 1). Assuming that a water molecule excludes other water molecules from a cubic region centered on itself, estimate the average distance between nearest-neighbor  water molecules in supercritical water at [itex]10^3[/itex] bar and 700 K.

Question 3) Calculate the molar volume of supercritical water at [itex]10^3[/itex] bar and 700 K from the ideal gas equation. What is the error, expressed as a percentage of the value, you computed in question 1)?

Question 4) At 700 K, the virial coefficient B* for water is  [itex]-1.1512\times 10^{-8} Pa^{-1}[/itex]. Calculate the molar volume of supercritical water at [itex]10^3[/itex] bar and 700 K from the virial equation. [itex]Z=P\overline{V}/RT=1+B^*P[/itex]
What is the error, expressed as a percentage of the value you computed in question 1)?

Question 5) Calculate the molar volume of supercritical water at [itex] 10^3[/itex] bar and 700 K from van der waals' equation. The van der waals' parameters for water are [itex]a= 5.537 bar L^2/mol^2, b=0.0305 L/mol[/itex] What is the error, expressed as a percentage of the value you computed in question 1)?

Question 6) Comment on the results in questions 2ꟷ5.


Answers:
   I don't know  molar mass of supercritical water. That's why i couldn't compute its molar volume [itex]m^3/mol[/itex] and L/mol.

 If we know answer to question 1), remaining questions can be answered easily except question 6)

[chenbeier]

I think molar mass of water will not change by physical changes. Its H2O and it is defined by the atoms in the molecule.