Activation Energy: Dependence Explained

In summary, the activation energy (Ea) is not dependent on temperature, but it can change if the Arrhenius equation is rearranged. However, the rate constant (k) will also change in relation to temperature, so Ea remains constant. This concept is often demonstrated in chemistry experiments by plotting lnk against 1/T and calculating the slope, which is equal to Ea/R.
  • #1
garytse86
311
0
Is activation energy dependent?

I think it isn't, but if you rearrange the Arrhenius equation you get:
Ea - activation energy
Ea = RT(lnA - lnk)
so as temperature Ea can change. But I am thinking that k will also change in relation so Ea is constant?
 
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  • #2
Ea is temp. independent, K will change with a change in T. So if T changes the -lnK factor will change so Ea will always be constant. A classical chemistry experiment at universities is plotting lnK vs. 1/T. The rate of the reaction at different temperatures is recorded in the lab. From the straight line in plot of lnk vs 1/T you can calculate the slope and the slope is equal to Ea/R.
 
  • #3
ok thanks very much.
 

FAQ: Activation Energy: Dependence Explained

What is activation energy?

Activation energy is the minimum amount of energy required for a chemical reaction to occur. It is the energy needed to break the bonds of the reactants and initiate the reaction.

Why is activation energy important?

Activation energy is important because it determines the rate of a reaction. Reactions with high activation energy require more energy to occur and are therefore slower, while reactions with low activation energy can occur more quickly.

How is activation energy related to reaction rate?

Activation energy and reaction rate are inversely proportional. As activation energy increases, the reaction rate decreases. This is because a higher activation energy means that more energy is needed for the reaction to occur, making the reaction slower.

What factors affect activation energy?

The temperature, concentration of reactants, and presence of a catalyst can all affect the activation energy of a reaction. Higher temperatures, higher concentrations, and the use of a catalyst can all lower the activation energy and increase the rate of the reaction.

Can activation energy be negative?

No, activation energy cannot be negative. It is always a positive value because it represents the minimum amount of energy needed for a reaction to occur. Negative activation energy would mean that the reaction could occur without any energy input, which is not possible.

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