Energy molecular kinetic energies

Kinetic theory A mathematical explanation of the behavior of gases on the assumption that gases consist of molecules in ceaseless motion in space. The molecular kinetic energy depends on the temperature of the gas. 

Fig. 8-4. Effect of temperature on atomic (or molecular) kinetic energy distribution.

At a given temperature, all gases have the same molecular kinetic energy distribution. 

Determine the average molecular kinetic energy and molar kinetic energy of gaseous sulfiar hexafluoride, SFfi, at 150 °C. 

The energies generated by forces among ideal gas molecules are negligible compared with molecular kinetic energies. 

A gas will obey the ideal gas equation whenever it meets the conditions that define the ideal gas. Molecular sizes must be negligible compared to the volume of the container, and the energies generated by forces between molecules must be negligible compared to molecular kinetic energies. The behavior of any real gas departs somewhat from ideality because real molecules occupy volume and exert forces on one another. Nevertheless, departures from ideality are small enough to neglect under many circumstances. We consider departures from ideal gas behavior in Chapter if. 

Looking at a little slice of the process fluid as our system, we can derive each of the terms of Eq. (2.18). Potential-energy and kinetic-energy terms are assumed negligible, and there is no work term. The simplified forms of the internal ener and enthalpy are assumed. Diffusive flow is assumed negligible compared to bulk flow. We will include the possibility for conduction of heat axially along the reactor due to molecular or turbulent conduction. 

Bodies of water at the same temperature have the same average molecular kinetic energies. The volume of the water has nothing to do with its temperature. 

Collisions between molecules or between a molecule and the walls of the container are perfectly elastic, i.e., there is no change in the molecular kinetic energy in a collision. 

What is the ratio of the average molecular kinetic energy of UFg to that of He, both at 300 K ... 

A. The same material is kept in a constant volume, so neither density nor the distance between molecules will change. Pressure will rise because of increasing molecular kinetic energy impacting container walls. 

Effect of Temperature on Surface Tension According to the kinetic theory, molecular kinetic energy is proportional to absolute temperature. The rise in temperature of a liquid, therefore, is accompanied by increase in energy of its molecules. Since intermolecular forces decrease with increase in the energy of molecules, the intermolecular forces of attraction decrease with rise of temperature. 

A is correct. During a phase change, temperature, and thus molecular kinetic energy, is constant. Breaking bonds always absorbs energy. Ice cools things when it melts. 

This equation shows that the absolute temperature is directly proportional to the average molecular kinetic energy, as postulated by the kinetic-molecular theory. Because there are molecules in a mole, the left-hand side of this equation is equal to the total kinetic energy of a mole of molecules. 

With this interpretation, the total molecular-kinetic energy of a mole of gas depends only on the temperature, and not on the mass of the molecules or the gas density. 

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