Organic chemists state that the rate of a chemical reaction can be doubled by increasing the reaction temperature by ten degrees Celsius. Explain this drastic increase in reaction rate using the concept of reactins and kinetic molecular theory
Most chemical reactions require enough energy for the molecules to exceed the activations energy of the reaction. A 10 degree rise is enough to exceed the energy requirements of most reactions and that is why so many of them are doubled. This "rule" is not absolute and it is isn't valid for much higher temperatures (mostly good for approximately room temperatures) but with KE = 1/2 mv^2 you can see that a higher temperature makes the molecules move much faster and KE is proportional to the SQUARE of the velocity.
To understand why increasing the reaction temperature by ten degrees Celsius can double the rate of a chemical reaction, we need to delve into the concepts of reactions and kinetic molecular theory.
Chemical reactions involve the breaking and forming of chemical bonds between atoms or molecules, resulting in the formation of new substances. The rate of a chemical reaction refers to how quickly the reactants are converted into products. This rate is influenced by various factors, including temperature.
According to kinetic molecular theory, molecules are in constant motion and possess kinetic energy. As the temperature increases, the average kinetic energy of the molecules increases as well. Higher kinetic energy leads to more frequent and energetic molecular collisions, which are essential for chemical reactions to occur.
When reactant molecules collide, they need to overcome a certain energy barrier, known as the activation energy, in order to transform into products. By increasing the temperature, the average kinetic energy of the molecules rises, increasing the proportion of molecules with sufficient energy to overcome this activation barrier. This results in a higher collision frequency of reactant molecules and a greater number of successful collisions.
Additionally, the increase in temperature increases the average speed of the molecules. According to the Arrhenius equation, the reaction rate is proportional to the exponential of the ratio of the activation energy to the product of the gas constant and the temperature. As the temperature increases, this exponential term becomes larger, thus increasing the reaction rate significantly.
In the context of organic chemistry, where intricate molecular structures and complex reactions are involved, small temperature changes can have a significant impact on the reaction rate. Therefore, increasing the reaction temperature by ten degrees Celsius can lead to a doubling of the rate of the chemical reaction, as it enhances molecular collisions and the energy available for breaking and forming chemical bonds.
In summary, by increasing the temperature, more molecules possess the required energy to overcome the activation energy barrier, resulting in a higher collision frequency and a greater number of successful collisions. These factors ultimately lead to a drastic increase in the rate of a chemical reaction.