# Activation energy and pre exponential factor

• Diamond101
In summary, activation energy is the minimum amount of energy needed for a chemical reaction to occur. It affects the rate of a reaction, with higher activation energies resulting in slower reactions. Factors such as temperature, concentration, and catalysts can influence the activation energy. The pre-exponential factor, represented by A in the Arrhenius equation, takes into account the frequency of collisions and orientation of reactant molecules. It can be determined experimentally by measuring the reaction rate at different temperatures and using the Arrhenius equation or by plotting a graph of ln(k) versus 1/T.
Diamond101

## Homework Statement

Calculate activation energy and pre exponential factor, i need help with the pre exponential factor

Temperature °C
-20 = 253 k
-10= 263
0=273
10=283
20=293
Rate const. s-1
1.15
3.85
11.3
28.7
74.0

## The Attempt at a Solution

i already plotted the graph on excel . i got ea= -(r * gradient)= -8.314*0.7703*10^4) =64 kj/mol
Pre exponential factor= E^(LN k + ea/RT) ^=E^(4.3+ 64/ 8.314*293 K) =?

What's the problem with keying these numbers into the calculator?

## 1. What is activation energy?

Activation energy is the minimum amount of energy required for a chemical reaction to occur. It is often described as the energy barrier that must be overcome in order for a reaction to take place.

## 2. How does activation energy affect the rate of a reaction?

The higher the activation energy, the slower the reaction will occur. This is because a higher amount of energy is needed to initiate the reaction, making it more difficult for the reactant molecules to overcome the energy barrier and form products.

## 3. What factors can affect the activation energy of a reaction?

The temperature, concentration of reactants, and presence of a catalyst can all affect the activation energy of a reaction. Higher temperatures and concentrations can lower the activation energy, while a catalyst can provide an alternate reaction pathway with a lower activation energy.

## 4. What is the pre-exponential factor in the Arrhenius equation?

The pre-exponential factor is represented by the letter A in the Arrhenius equation, which describes the relationship between the rate constant of a reaction and the temperature. It is a constant that takes into account the frequency of collisions between reactant molecules and their orientation in a reaction.

## 5. How can the pre-exponential factor be determined experimentally?

The pre-exponential factor can be determined by measuring the rate of a reaction at different temperatures, and then using the Arrhenius equation to calculate the value of A. This can also be done by plotting a graph of ln(k) versus 1/T, where the slope of the line is equal to -Ea/R and the y-intercept is ln(A).

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