JEE Advanced2006ChemistryStates of MatterActual
The given graph represent the variations of compressibility factor (Z)= P V n R T versus P , for three real gases A, B and C . Identify the only incorrect statement
Options
- AFor the gas A, a=0 and its dependence on P is linear at all pressure.
- BFor the gas B, b=0 and its dependence on P is linear at all pressure.
- CFor the gas C , which is typical real gas for which neither a nor b=0 . By knowing the minima and point of the
- DAt high pressure, the slope is positive for all real gases.
Correct answer
B. For the gas B, b=0 and its dependence on P is linear at all pressure.
Step-by-step solution
From the graph it is clear that the value of Z decreases with increase of pressure. We can explain as follows on the basis of van der Waals' equation. At high pressure, when ' P ' is large, V will be small and one can not ignore ' b ' in comparison to V . However, the term a V^2 may be considered negligible in comparison to ' p ' in van der Waals' equation or aligned (p+ a V^2 )(V-b) & =n R T P(V-b) & =n R T p V-p b & =n R T p V n R T & =1+ p b n R T Z & =1+ p b n R T aligned or Here, Z is greater than one and it i