Chemical kinetics?

Question

What does arrenius equations tells us about a chemical reaction?
what is collision theory?
how rate of reaction is dependent on temperature?

Answer 1

The Arrhenius equation tells us the rate of the chemical reaction.

Rate = A * exp(-Ea/RT)

Where A is a constant, Ea is the activation energy, R is the universal gas constant, and T is the temperature in Kelvin.

For constant Ea (i.e., the activation energy is not temperature dependant -- a reasonably good assumption) and constant concentrations of reactants:

As temperature increases, the exponent increases (because it is a negative exponent), and the rate increases. As temperature decreases the rate slows down. This is because temperature is actually a measure of the average kinetic energy of the molecules. As the molecules increase in energy they are able to pass the activation energy barrier more quickly. Think of the activation energy as a chasm or stream you need to cross -- the faster you run, the easier it is to jump across.

The collision theory basically means that in order for a reaction to occur, the molecules must come in contact with each other (collide). Not all collisions result in a reaction. Some molecules simply do not react with each other and simply bounce off each other. Others can react with each other, but must hit each other hard enough AND must have the correct orientation in order to react.

Answer 2

Course one major problem with the Arrhenius equation written in the form above me is that the constant A is typically very difficult to ascertain as it depends on several factors of the given system. To overcome this, one could write the equation in

ln(k2/k1)= -Ea/R (1/T1 - 1/T2)

I won't go through how to get this as it is a simple thing of logarithms. But notice that in this form that the constant A is gone and thus makes this a more practical form of the equation.

Answer 3

R = Aexp(-E/RT)

Answer 4

how about you do your own homework?