Background Research

Rate of Chemical Reactions

A chemical reaction is a process in which the molecular or ionic structure of a substance is rearranged to form a completely new substance. The rate of a reaction is the speed at which a reaction happens. If a reaction has a high rate, that means the molecules combine at a faster speed than a low rate reaction. Reactants are the original chemicals and products are the chemicals that are created when two or more reactants are combined. A catalyst increases the speed of a chemical reaction by providing an alternate path with a lower activation energy barrier. Activation energy is the minimum amount of energy that must be inputted by the reacting species in order to undergo a specific reaction.

A high activation energy barrier makes a reaction go slower because it takes longer to overcome the barrier. The collision theory says that as more collisions occur in a system, there will be more combinations of molecules bouncing into each other and the reaction will go faster. A few things such as concentration, surface area, temperature, and pressure can affect reaction speed. If all of these things are higher in different situations, the reactions will be faster. The rate of a chemical reaction is the change in concentration over the change in time. Some chemical reactions can take thousands of years while others take less than a second. The presence of a catalyst helps a reaction proceed more quickly to reach equilibrium. Other chemical species can decrease the rate of a reaction when they compete for a reactant or alter the orientation of reaction. Chemical reactions occur everywhere and all the time at different rates.

Reversible Reactions

Reversible reactions are reactions that can proceed in either direction (forward or backward), because reactants are not completely used to form products. Reactants are converted into products during forward reactions, and products are converted into the original reactants during backward reactions. Reactions in both directions occur simultaneously, but depending on the conditions, one will be stronger than the other. If the forward reaction is exothermic, then the backward reaction is endothermic, vice versa. The energy transferred in the forward reaction will be equal to the energy in the backward reaction. When equilibrium has been reached, the forward reaction is making products at the same rate that the backward reaction is making reactants.