Ques. 1AIPMT 2002
Van der Waals real gas acts as an ideal gas at which conditions?
- High temperature, low pressure
- Low temperature, high pressure
- High temperature, high pressure
- Low temperature, low pressure
Answer
(1) High temperature, low pressure
Solution
van der Waals equation: (p + an2V2 )(V - nb) = nRT
A real gas behaves ideally when both corrections become negligible.
⇒ At low pressure the volume V is very large, so nb V (own volume of molecules negligible) and an2V2 is negligible (molecules far apart).
⇒ At high temperature the kinetic energy of molecules is large, so intermolecular attractions become negligible.
∴ As per NCERT, real gases show ideal behaviour at low pressure and high temperature (Z 1).
Answer: (1)
Out of syllabus