Average and Instantaneous Rate

In any chemical reaction, the reaction rate is the rate at which the concentration rises or falls or the rate at which mass changes.

The reaction rate refers to the rate of reaction in a chemical reaction. The reaction rate of a chemical reaction is defined as the rate of change in the mass of the reactant, divided by the rate of change in the mass of the product. For example, to determine the rate of reaction for an elementary reaction, you must know the initial and final concentrations of the reactant (the mass of reactant), the initial and final concentrations of the product (the mass of product) and the heat of reaction.

In this article, we shall learn about the factors affecting the reaction rate and its examples.

Factors Affecting the Reaction Rate

Average Rate of Reaction 

The average rate of a chemical reaction is the speed at which it occurs per unit of time. The Average Rate of Reaction is the average speed at which a substance will burn or react with a catalyst. 

Instantaneous Rate of Reaction

The instantaneous rate of reaction is the rate at which the reaction occurs at any given moment. It is often given in terms of the speed at which the reaction occurs in a given volume of solution per unit of time, such as moles per litre per second or kilograms per litre per second. 

Temperature

In a typical chemical reaction, the rate of reaction is an exponential function of temperature. This is sometimes called the Arrhenius law, after the Swedish scientist who proposed its first version. The effect of the temperature on the reaction rate can be explained by the Arrhenius equation, which takes into account the changes in activity coefficients. 

Arrhenius’ idea is that the rate of a chemical reaction is proportional to the products of the reactants and the absolute temperature. For an ideal gas, the energy is evenly distributed between all the particles, so the higher the temperature, the higher the kinetic energy. As a result, the molecules collide more often and consequently more often.

Number of Reactants

The rate of reaction increases with the number of reactants. The speed of the reaction can be increased by a change in the amount of chemical energy introduced to the system. Because of the amount of energy involved, the reaction rate is much greater at a lower temperature. Therefore, the rate of reaction is proportional to the number of reactants.

Pressure

A gas that is less reactive than air increases the pressure required to compress it. As the pressure rises, the rate at which a reaction takes place also increases. This effect is also seen in the reaction rates of some solid substances. In the case of solids, the pressure has little effect on the reaction as the atoms are more tightly bound and thus do not move as easily.

Shape And Size of The Catalyst

A catalyst is a substance that speeds up the reaction rate. The size of the particles influences the reaction rate, as it can cause the reaction to be either slow or fast. This is due to the fact that the smaller the catalyst, the more contact between reactant and catalyst.

Reaction Medium

The rates of reaction of the reactant in the presence of the catalysts are different. In the absence of catalysts, the reaction does not happen. In an acid medium, the reaction is sluggish and takes a long time to complete. In the presence of the catalyst, the reaction goes very fast. The dependence of reaction rate on the reaction medium is dependent upon the reactants. When the reactants are liquid, the reaction rate is the highest. The reaction rate is lower when the reactants are in a solid state.

Type of System

In a closed system, the reaction rate is faster than in an open system. This is because, in an open system, the reagent cannot contact the catalyst as easily as it can in a closed system. When the reaction is in a closed system, the reagent and the catalyst are surrounded by a protective layer. When the reagent reaches the catalyst, it must go through the protective layer before it can react with the catalyst.

Reaction Time 

The reaction rate is directly proportional to the reaction time. A longer reaction time results in a reduction in the overall reaction. The rate of a reaction depends on the time it takes to react. In an experiment, the rate of the reaction is measured. The rate at which a reaction occurs can be thought of as a function of time.

Concentration

At a constant temperature, the dependence of reaction rate on concentration is a linear function of the reactant concentration. In other words, the amount of reaction is directly proportional to the reactant concentration and reaction rate.

Solubility

The most important factor that affects the reaction rate is the solubility of the compound. The rate is directly proportional to the amount of solvent added to the reaction. If the amount of solvent is too small, the reaction will not occur. As the amount of solvent increases, the reaction rate will decrease.

Conclusion

The reaction rate is the rate at which a reaction occurs. In general, the reaction rate is the rate at which a chemical change occurs. When we talk about the reaction rate of a chemical reaction, it is the rate at which the reaction occurs per unit of time. The reaction rate is influenced by the reactants, reaction conditions, and catalysts. These factors affecting the reaction rate are important. The reaction rate depends on the relative amounts of reactants and catalysts, the temperature and the pressure (how tightly the reactants are packed together). The rate of chemical reactions can be affected by temperature, pH, and concentration of reactants and products.