Chemical Kinetics

From UBC Wiki
Jump to: navigation, search
ChemHelp.png This article is part of the ChemHelp Tutoring Wiki


The study of the rate at which reactant molecules are converted to products in a chemical reaction. This means that how quickly reactants are converted into products

Reaction rate

The rate at which reactants are converted into products in a reaction. Note that chemical reactions involve breaking old bonds (in the reactants) and making new bonds (in products). In order to bond breaking and bond making to occur, reactant molecules ( or atoms or ions) must collide with sufficient energy and proper orientation.

Factors that Affect Reaction Rate

Concentration of Reactants

Reactant molecules must collide in order to form products. IF the rate at which reactant molecules collide is increased, then the reaction rate will also increase. One way to increase the rate of reactant collisions is to increase the amount of Reactant present, or , in the other words, to increase the concentration of reactants.

Surface Area of Reactants

The greater the surface area of the reactants, the greater the number of collisions hence the faster the reaction rate. For example, a cube of suar will dissolve liss quickly in water than will the same amount of sugar in loose form.


The factor that has perhaps the most profound effect on reaction rate. Note that temperature is a measure of the average kinetic energy of molecules. As the temperature of the reactants is increased, the molecules move around faster; this results in more frequent and energetic collisions and increases the likelihood that a given collision will have sufficient energy to break bonds. For every 10 C increase in temperature, the reaction rate will double.


a catalyst increases the rate of a chemical reaction without being consumed by it. Enzymes are examples of catalysts. So how does catalysts works? Catalysts increases the reaction rate by enabling the reaction to proceed through a series of different steps, with lower activation energy, then they ordinarily would. So catalysts reduces the minimum energy requirement of the reaction. this leads to a greater percentage of product-formnig collisions and thus an increased rate of reaction.

Note: catalysts is not consumed in the reaction

To concluded,

1. catalysts increase rate of a reaction by lowering the activation energy

2. catalysts are not consumed in a reaction.

3. catalysts do not change the equilibrium of the reaction

Back to ChemHelp Back to Chem154