A Rate Law and Activation Energy Chemistry 1310 2 – Studocu

When it comes to chemistry, there are a lot of different concepts that you need to understand in order to be successful. One of these concepts is the rate law. The rate law is important because it tells us how fast a reaction will occur. It also tells us what factors affect the rate of a reaction. In this blog post, we will be discussing the rate law and activation energy. We will go over what they are and how they are related. We will also discuss how the rate law can be used to determine the activation energy of a reaction.

What is a rate law?

In order to determine the rate law of a chemical reaction, the following steps must be undertaken:
1. Experimentally measure the rate of the reaction at various concentrations of reactants.
2. Based on the experimental data, determine the order of the reaction with respect to each reactant. The overall order of the reaction is the sum of the orders with respect to each reactant.
3. Use the integrated rate laws to determine the specific rate law expression for the reaction. The integrated rate laws take into account the orders of reactions determined in step 2.
4. Experimentally determine the value of the rate constant, k, for the reaction by measuring the initial rates of reactions at different temperatures (for zeroth-order and first-order reactions) or measuring the half-life of a reaction (for second-order reactions).

What is activation energy?

Activation energy is the minimum amount of energy that is required to start a chemical reaction. It is often represented by the symbol Ea. The activation energy can be thought of as the height of the “energy barrier” that must be overcome for a reaction to occur. In order for a reaction to take place, the reactants must have enough energy to overcome this barrier.


Once they have done so, the products will have lower energy than the reactants and the reaction will proceed. The activation energy can be supplied in many different ways, including heat, light, or electrical current. The amount of activation energy required for a particular reaction will determine how fast it occurs. Generally, reactions with higher activation energies will occur more slowly than those with lower activation energies. This is because it is easier for the reactants to collide and form products when they have less energy to overcome. Activation energies can vary widely, from just a few kJ/mol to hundreds of kJ/mol.

What is the Arrhenius equation?

The Arrhenius equation is a mathematical model that describes how the rate of a chemical reaction varies with temperature. The equation was developed by Swedish chemist Svante Arrhenius in 1884. The equation can be used to predict the rate of a reaction at any given temperature, provided that the rate is known at one other temperature. The equation has the form:

rate = A * e^(-Ea/RT)

where A is the frequency factor, Ea is the activation energy, R is the gas constant, and T is the absolute temperature.

What are the factors that affect reaction rate?

The rate of a chemical reaction is affected by several factors. The following list enumerates some of the most important ones:

1. Concentration of reactants: All else being equal, the higher the concentration of reactants, the higher the rate of reaction. This is because there are more molecules participating in collisions, and thus more chances for a successful reaction to occur.

2. Nature of reactants: Some substances simply react faster than others. For example, hydrogen and chlorine gas will combine very rapidly to form hydrochloric acid, while methane (natural gas) and oxygen will only reluctantly form carbon dioxide and water vapor.

3. Surface area of reactants: If two otherwise identical solutions are mixed together, but one has its particles ground into a powder while the other remains in large chunks, the powdered solution will have a much higher rate of reaction because there is more surface area for collisions to occur. This is why liquid reactions often happen much faster when they are stirred – it increases the surface area by breaking up the liquid into smaller droplets.

4. Temperature: In general, increasing temperature will increase the rate of reaction. This is because heat provides energy that can be used to overcome activation barriers (see below). However, there are some exceptions to this rule – some reactions actually proceed more slowly at higher temperatures, due to other effects such as product instability or changes in equilibrium constants.

5. Pressure: For gases reacting with each other,

How can you determine the rate law for a reaction?

One way to determine the rate law for a reaction is to measure the rate of the reaction at different concentrations of reactants. The concentration of each reactant is usually varied while keeping the concentration of the other reactants constant. The resulting data are then plotted to obtain a rate vs. concentration graph. From this graph, the order of the reaction with respect to each reactant can be determined. The overall order of the reaction can then be determined from the orders of each reactant.


How can you determine the activation energy for a reaction?

The activation energy for a reaction can be determined by measuring the rate of the reaction at various temperatures and plotting the data on a graph. The activation energy can be calculated from the slope of the line on the graph.


In conclusion, rate law and activation energy are important concepts in chemistry. A rate law helps to determine the speed at which a chemical reaction occurs, while activation energy is necessary to start the reaction. By understanding these concepts, chemists can better control and predict chemical reactions.

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