Given van der Waals’ constant for NH3, H2, O2 and CO2 are respectively 4.17, 0.244, 1.36 and 3.59, which one of the following gases is most easily liquefied?
- NH3
- H2
- O2
- CO2
Answer
(1) NH3
Solution
The van der Waals constant a is a measure of the magnitude of intermolecular attractive forces.
Larger a ⇒ stronger attraction ⇒ higher critical temperature ⇒ gas is liquefied more easily.
Order of a: NH3 (4.17) > CO2 (3.59) > O2 (1.36) > H2 (0.244)
∴ NH3 is most easily liquefied.
Answer: (1)