The rates of chemical reactions and the ability to control those rates are crucial aspects of life. Chemical kinetics is the study of the rates at which chemical reactions occur, the factors that affect the speed of reactions, and the mechanisms by which reactions proceed. The reaction rate depends on the reactants, the concentrations of the reactants, the temperature at which the reaction takes place, and any catalysts or inhibitors that affect the reaction. 

 

The rate of a chemical reaction is the time required for a given quantity of reactant(s) to be changed to product(s). Reaction rate usually is expressed in terms of moles per unit time.  If a chemical reaction has a fast rate, a large portion of the reactant molecules react to form products in a given time period. If a chemical reaction has a slow rate, a small portion of reactant molecules react to form products in a given time period.  

 

A chemical reaction is the result of effective collisions between particles of reactants. 

Increasing the temperature of the system raises the potential energy and average kinetic energy of the reactants particles of the system. This results in more collisions and, of greater importance, more effective collisions per unit time. This affects the rate of reaction. At constant temperature, increasing the concentration of one or more of the reactants increases the number of reactant particles present and, hence, the number of collision. This results in more effective collisions and affects the rate of reaction. 

 

You will investigate the effect of temperature (or concentration of solutions) that will affect the rate of reaction. This investigation should provide a better understanding of reaction rates and the factors that affect these rates.  

 

 

Synopsis 

You will investigate the effect of temperature (or concentration) that affects the rate of reaction and present your findings in the form of a scientific report. This investigation involves reaction of sodium thiosulfate with hydrochloric acid. The reaction, which produces solid sulfur (yellow deposit), will be followed by measuring the time needed for the reaction mixture to become opaque.