# Calculating Activation Energy and Rate Constant for a Chemical Reaction

• kittymaniac84
In summary, the conversation discusses the calculation of activation energy for a reaction using the Arrhenius equation. The rate constant values for the reaction are given at two different temperatures and the equation is used to solve for the unknown variables. The final value for the rate constant at 425 K is 4.06x10^-3.
kittymaniac84
[SOLVED] Activation energy

The reaction, 2NOCI (g) = 2NO (g) + Cl$$^{}_2{}$$(g) , has rate constant values for the reaction of NOCl of 9.3 x 10^-6 Is at 350 K and 6.9 x 10^-4 Is at 400 K. Calculate the activation energy for the reaction. What is the rate constant at 425 K?

I am unsure how to solve this. Can someone help me and show me how to do it.

SCREAMS arrhenius equation.

Excuse me, why the rude behavior? This is suppose to be a help forum. It might be obvious to you, but I'm not sure if I am using the equation right.

The Arrhenius equation is ln(k) = ln(A) - E/(RT). You are given values of k at two different temperatures T. R is the gas constant, A and E are empirical constants, E being the activation energy. So just plug the corresponding values (k,T) into this equation to generate two equations in two unknowns. After you know A and E, use the equation to get k at any other T. Does this help?

Yes thank you. I already figured this out on my own. That is exactly what I did. Ea=100,232, A=8.47x10^9, and with T=425 I got 4.06x10^-3 for k.

I hope i did the math right but it looks right.

## What is activation energy?

Activation energy is the minimum amount of energy required for a chemical reaction to occur. It is similar to the energy needed to start a fire - a certain amount of heat is needed to ignite the reaction.

## Why is activation energy important?

Activation energy is important because it determines the rate at which a chemical reaction will occur. The higher the activation energy, the slower the reaction will be. It also helps to prevent unwanted or dangerous reactions from occurring too quickly.

## What factors affect activation energy?

The factors that affect activation energy include temperature, concentration of reactants, and the presence of catalysts. Higher temperatures and higher concentrations of reactants typically result in lower activation energy, meaning the reaction will occur more quickly. Catalysts can also lower activation energy by providing an alternative pathway for the reaction to occur.

## What happens to activation energy in an exothermic reaction?

In an exothermic reaction, the reactants have more energy than the products. This means that the activation energy for the reaction is negative, and the reaction can occur spontaneously without any additional energy input.

## How can activation energy be calculated or measured?

The exact value of activation energy cannot be directly measured, but it can be calculated using the Arrhenius equation. This equation relates the rate of a reaction to the temperature and activation energy. Scientists can also use experiments to determine the temperature at which a reaction occurs at a specific rate, and then use the Arrhenius equation to calculate the activation energy.

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