Chemistry

Difference between Reaction Rate and Rate Constant

Main difference

The main difference between reaction rate and rate constant is that reaction rate refers to moles per second as the change in molar concentration of reactants and products with time, while rate constant refers to the constant of proportionality for a particular chemical. reaction.

Reaction Rate vs. Constant Rate

The reaction rate is defined as the change in the number of reactants and products with time, while the rate constant is defined as the specific constant of proportionality of a particular chemical reaction. The reaction rate depends directly on the molar concentrations of reactants and products, while the rate constant does not depend on the molar concentrations of reactants and products. The rate of a reaction depends indirectly on physical properties such as temperature; on the other hand, the rate constant is directly based on physical properties such as temperature.

The reaction rate mainly needs the completion time of a reaction on the other hand; the rate constant does not need the completion time of a reaction. The rate of a reaction depends on pressure, while the rate constant does not depend on pressure. The reaction rate can change with the help of catalysts while the rate constant shows no change in the presence of catalysts.

The reaction rate is always expressed in moles per second, while the rate constant is taken directly from the reaction. The reaction rate unit is not subject to a reaction order, while the constant rate unit is subject to the reaction order or can be found out with the help of a reaction order. The reaction rate depends directly or indirectly on the frequency of collisions, while the constant rate does not primarily depend on the frequency of collisions.

Comparison chart
reaction rate constant rate
The reaction rate is defined as the variation of the number of reactants and products with time. Rate constant defined as the specific proportionality constant of a particular chemical reaction.
molar concentration
Rest on molar concentration Does not rest on molar concentration
Hour
Depends on reaction time It does not depend on reaction time.
Temperature
It depends indirectly on the temperature essentially depends on the temperature
Pressure
depends on the pressure Does not depend on pressure
catalysts
Depends on catalysts Does not depend on catalysts
collision frequency
Depends on collision frequency Does not depend on collision frequency
reaction order
Its unit depends on the reaction order. Its unit does not depend on the reaction order.

What is the reaction rate?

Reaction rate refers to the change in moles per second in the concentration of reactants and products with time. It also depends on physical properties such as temperature. It fluctuates with temperature deviation. It also depends on the completion time of the reaction. The longer the time, the higher the reaction rate value.

It depends indirectly on the temperature. It can be changed with the change of pressure and catalysts. The main factor involved in increasing the value of the reaction rate is the increase in the collision frequency of the reacting molecules. The reaction rate units can be found with the help of the reaction order.

The rate of reaction is always said to increase if the molar concentration of the reactants decreases and the molar concentration of the products increases. In the same way, the reaction rate is always said to decrease if the molar concentration of reactants increases and the molar concentration of products decreases.

What is the rate constant?

Rate constant defined as the specific proportionality constant. It is not based on the concentration of moles. It is important that it is based on physical properties such as temperature. It can only change with the change of temperature. Other quantities do not affect the rate constant, such as pressure and catalysts.

It also does not depend on time to complete a reaction. It does not change if a reaction occurs in a short time or occurs abruptly. The collision frequency of the reacting molecules does not affect the change in rate constant. K can denote it.

This constant is useful and determines the reaction rate at any time during the reaction. The increase or decrease of a rate constant can only be determined by physical properties such as temperature.

Key differences

  1. The reaction rate is the change in the number of reactants and products as time increases, while the rate constant is the constant of proportionality present in a certain chemical reaction.
  2. The rate of reaction resides mainly in the molar concentrations of reactants and products, while the rate constant is not found in the molar concentrations of reactants and products.
  3. The reaction rate is not directly dependent on physical properties such as temperature; on the other hand, the rate constant depends directly on physical properties such as temperature.
  4. The reaction rate mainly takes the time needed to achieve a reaction; on the other hand, the rate constant does not take the time needed to achieve a reaction.
  5. The rate of a reaction is exposed to pressure, while the constant rate does not depend on pressure.
  6. The reaction rate can change its mechanism with the help of catalysts, while the constant rate does not show any change in its mechanism on the occurrence of catalysts.
  7. The reaction rate is expressed in moles per second, while the rate constant is carried out from the right of reaction.
  8. The reaction rate totally depends on the frequency of collisions, while the rate constant does not depend on the frequency of collisions.
Final Thoughts

The above discussion concludes that the rate of reaction is the molar change in concentration of reactant and product per unit time, while the rate constant is the constant of proportionality for a specific reaction.

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