Question

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Answer 1

Answer:

The deviations are :

• The activation energy which changes with temperature
• The arrhenius constant which depends on the temperature

Explanation:

• There are deviations from the Arrhenius law during the glass transition in all classes of glass-forming matter.

• The Arrhenius law predicts that the motion of the structural units (atoms, molecules, ions, etc.) should slow down at a slower rate through the glass transition than is experimentally observed.
• In other words, the structural units slow down at a faster rate than is predicted by the Arrhenius law.
• This observation is made reasonable assuming that the units must overcome an energy barrier by means of a thermal activation energy.
• The thermal energy must be high enough to allow for translational motion of the units which leads to viscous flow of the material.

• Both the Arrhenius activation energy and the rate constant k are experimentally determined, and represent macroscopic reaction-specific parameters that are not simply related to threshold energies and the success of individual collisions at the molecular level.
• Consider a particular collision (an elementary reaction) between molecules A and B. The collision angle, the relative translational energy, the internal (particularly vibrational) energy will all determine the chance that the collision will produce a product molecule AB.
• Macroscopic measurements of E(activation energy) and k(rate constant ) are the result of many individual collisions with differing collision parameters. They are averaged out to a macroscopic quantity.