ACTIVATION ENERGY Temperature and Rate of Reactions For

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ACTIVATION ENERGY

ACTIVATION ENERGY

Temperature and Rate of Reactions For a chemical reaction to occur, molecules must undergo

Temperature and Rate of Reactions For a chemical reaction to occur, molecules must undergo effective collisions with the necessary energy (called the activation energy) for the reaction to take place.

Temperature and Rate of Reactions ■ The following energy diagrams show an exothermic and

Temperature and Rate of Reactions ■ The following energy diagrams show an exothermic and an endothermic reaction. ■ The “energy hill” represent the activation energy (Ea). ■ The higher the activation energy, the slower the reaction, conversely, the lower the activation energy, the faster the reaction. ■ At the top of the “energy hill” is the transition state where bond breaking and bond forming is taking place.

Temperature and Reaction Rate ■ Several factor affect the energy of activation. However, in

Temperature and Reaction Rate ■ Several factor affect the energy of activation. However, in this section will focus on how temperature affects the energy of activation, which in turn affects the rate of the reaction. ■ The Maxwell-Boltzman distribution curve shows the effect of temperature on the kinetic energy of molecules. ■ When the temperature increases, the average speed of molecules increases and the number of molecules with KE greater than Ea also increase. This means that there will be an increase in the number of effective collision. It is the increase in the number of effective collisions that is mainly responsible for the increase in the reaction rate as the temperature is increased.

Arrhenius Equation

Arrhenius Equation

Using the Arrhenius equation to calculate the activation energy ■ If we take the

Using the Arrhenius equation to calculate the activation energy ■ If we take the natural logarithm of both sides of the Arrhenius equation, we find that:

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