Chemical reactions occur everyday in life, in our body, in the atmosphere, in oceans, etc. Understanding chemical reactions helps scientists understand how things works, such as how photosynthesis is achieved to something as simple as how NaCl (table salt) is made. Several factors effect the rate of chemical reactions such as concentration of reactants, pressure, temperature, catalyst, nature of reactants, orientation of reacting species, surface area, intensity of light, and nature of solvent. In general a chemical reaction will either be exothermic, releasing energy, or endothermic, gaining energy.
Factors affecting the rate of chemical reactions
The more concentration of reactants one has the faster it will go, meaning the rate of reaction is directly proportional to the concentration of the reactants. It will go faster because there is a higher probability for the reactants to collide and interact with each other. Equation: rate (r)= c^n, where c=concentration and n=order of the reaction.
This mainly affects the rate of reaction in gasses. In is very similar to the concentration that is if you increase the partial pressure of the gasses there is a higher probability for the gas molecules to collide and react.
This affects the rate of reaction because the average kinetic energy of the molecules is higher thus there will be a higher frequency of the molecules to collide and react with one another.
Catalyst is a substance that increases the rate of reaction by lowering the activation energy required for the reaction to proceed. It is not consumed or changed throughout the reaction.
Nature of reactants
In general ionic bonds are formed faster than covalent bonds because in covalent compounds there has to be a bond breakage that will slow down the entire reaction, whereas in ionic bond it is more or less a substitution of ions.
Orientation of Reacting species
If the reactants are more complex it will make it difficult and lower the probability for the reactants to collide with the correct orientation for the reaction to occur. Opposing that is simple reactants where the probability for the reactants to collide with the correct orientation is high. Therefore complex reactants will have a slower reaction time than simple reactants because the probability for the reactants to collide in the correct orientation and react is low.