Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Specific Heat Capacities of Gases
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Specific Heat Capacities of Gases
At STP, the molar heat capacity of oxygen gas is nearly 2.5 R ....
At STP, the molar heat capacity of oxygen gas is nearly . With an increase in temperature, it gradually rises and approaches . The most fitting reason for this behaviour is that at high temperatures
Options
- Amolecular vibrations progressively become effective
- Boxygen does not behave like an ideal gas
- Cthe molecules undergo collisions more frequently
- Doxygen molecules dissociate into atoms
Correct answer
A. molecular vibrations progressively become effective
Step-by-step solution
At STP, oxygen () acts as a rigid diatomic molecule with translational and rotational degrees of freedom.
Total degrees of freedom, .
The molar heat capacity at constant volume is .
At high temperatures, the vibrational degrees of freedom become active. A diatomic molecule has one vibrational mode, which contributes additional degrees of freedom (one for kinetic energy and one for potential energy).
Total degrees of freedom at high temperature, .
The molar heat capacity becomes .
Thus, the increase in molar heat capacity is due to the molecular vibrations progressively becoming effective at higher temperatures.
Total degrees of freedom, .
The molar heat capacity at constant volume is .
At high temperatures, the vibrational degrees of freedom become active. A diatomic molecule has one vibrational mode, which contributes additional degrees of freedom (one for kinetic energy and one for potential energy).
Total degrees of freedom at high temperature, .
The molar heat capacity becomes .
Thus, the increase in molar heat capacity is due to the molecular vibrations progressively becoming effective at higher temperatures.