What do you mean by Reaction Rate Constants

......."A reaction is defined as a process in which a substance is converted into a new substance with changing their physical as well as chemical properties"........
A chemical reaction essentially involves products and reactants. In addition, certain critical conditions are required for the chemical reaction to proceed until its completion. These conditions include proper temperature and pressure, ionic strength, etc. However, every chemical reaction can be explained using two terms: "Rate Of Reaction And Rate Constant".
Let's have a look a chemical reaction,
A + B ➞ C + D 
                ––––––––(1)
Here, A and B are reactants and C and D are products.
The rate law for this reaction is written as;
➩ { r = k[A]ⁿ [B]ᵐ......... }
                      –––––––––(2)
  Where, k = Represent the "Rate Constant" or a proportionality constant
Equation (2) is known as the "Rate Law" for above reaction-(1).

Reaction Rate Constants
........."A reaction rate constant is defined as a proportionality constant that appears in the rate law of a particular reaction. Its value is equal to the rate of the reaction when the concentration of each reactant is unity"........ 
Reaction rate constant is independent of the concentration of reactants and products but its value depend on the other factors like temperature & pressure, etc (Essentially on temperature). 
For a particular temperature, the rate constants have a definite value that will change according to the changes in temperature. This temperature dependence is given by the equation called “Arrhenius Equation”. This equation indicates the effect of temperature change on rate constant as well as the effect of a catalyst. Increasing the temperature increases the rate constant.

Reaction rate constant is also independent of the time taken for the reaction to complete. The symbol for the rate constant is “k”. 
For Example 
A reaction is proceeding in the following manner, 
                  A ➝ Products
 The rate law for the above reaction is, 
 reaction rate, 
                  r = d[A] /dt = k[A]¹
          Here, 
                 k is reaction rate constant 

Unit Of Reaction Rate Constant
The unit of the reaction rate constant depends on the order of the reaction. The unit of a reaction rate constant for the nth-order reaction is given by;
"Time⁻¹ Concentration⁽¹⁻ⁿ⁾"
Here, n is defined as an order of reaction and based on the different values of n, the unit of reaction rate constants are also different. 



Hope you have found this article helpful!!
Do you have suggestions? Please write in comment box!!!
Feel free to comment if you have any queries!!

Comments

Post a Comment

Most Viewed Posts

Zeroth Law Of Thermodynamic: The Thermal Equilibrium Law

Image
In thermodynamics, we will see two types of walls. One is the Diathermic wall and the other is the adiabatic wall. Let us now go through them one by one.  • So the first is the Diathermic wall- " A Diathermic wall is a wall that allows the easy exchange of heat between two bodies (or between two systems or between system and surrounding) but does not allow the exchange of mass between them ". This means that it is a good conductor of heat. It is sometimes called as metallic wall because it is made of metal. • While the other is the adiabatic wall- " An Adiabatic wall is that wall which neither allows exchange of heat nor mass between two systems (or between system and surrounding) ". Since there is no exchange of heat and mass between the system and its surroundings, the system remains insulated from its surroundings. ➛ That's why whenever we separate the two systems by an adiabatic wall, then there is no concept of equilibrium between them. But whenever we sep...
Read more

Characteristics Of Entropy

Image
Entropy is an intrinsic property of a substance and is not affected by the external position of a system or its motion relative to other systems. It is a measure of the randomness of the system. Thus, the higher the randomness of the system, the higher the entropy of the system and the lower the randomness of the system, the lower the entropy of that system. Entropy   " Entropy is defined as a measure of the system's thermal energy that is incapable of doing work ". It is a state function.  For Example Heat is a form of energy that is incapable of doing work. Therefore, the more heat added to the system (or tranfer from the system), the higher (or the lower) will be its entropy.  The formula for change in entropy is given by the equation;                      ➩ ∆S = ∆Q/T For a reversible process, the change in entropy is given as; The Total Change In Entropy Entropy change is zero at equilibrium condition or whenev...
Read more

Reversed Carnot Cycle

Image
We have already discussed the concept of “ Carnot Cycle ”   & “ Its Efficiency ” and we have also seen the concept of “ Carnot Theorem And Its Explanation ” in our previous post. As we have already discussed that the Carnot Cycle is a reversible cycle and every process in the Carnot cycle is a reversible process. Therefore, every process of the Carnot cycle can be reversed. And the cycle can be operated in the opposite direction as well. In this article, we're interested in learning more about the reversed Carnot cycle, also known as the reversed Carnot heat engine cycle. Reversed Carnot Heat Engine It is important to note that if a reversible process is reversed, all related energy types—such as heat energy or work energy—will have the same magnitude but the direction of their interaction with matter will be changed. Let us first look at the Reverse Carnot Heat Engine  cycle here; The reversed Carnot heat engine cycle is depicted in the following figure. According to the...
Read more