Interept the graph (fig4.8) and (fig 4.9) given in the chapter chemical kinetics.And why two fraction of molecules have differrent amount of kinetic energy?

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Interept the graph (fig4.8) and (fig 4.9) given in the chapter chemical kinetics.And why two fraction of molecules have differrent amount of kinetic energy?

Asked by jorben_999 | 18 Jul, 2010, 07:29: PM

Expert Answer

fig 4.8

The graph is between fraction of molecules (N_E/N_T) with a given kinetic energy (E) vs kinetic energy. Here, N_E is the number of molecules with energy E and N_T is total number of molecules.The energy possessed by maximum number of meloecules is called the most probabale energy.The peak of the curve corresponds to the most probable kinetic energy,
i.e., kinetic energy of maximum fraction of molecules.

fig. 4.9

When temperature changes the most probable energy changes. When the temperature is raised, the maximum of the curve moves to the higher energy value and the curve broadens out, i.e., spreads to the right. This means that there is a greater proportion of molecules with much higher energies.

Increasing the temperature of the substance increases the fraction of molecules, which collide with energies greater than Ea. It is clear from the diagram that in the curve at (t + 10), the area showing the fraction of molecules having energy equal to or greater than activation energy. Thus, activation energy gets doubled leading to doubling the rate of a reaction.

Answered by | 22 Jul, 2010, 11:24: AM