Chemical Equilibrium Research Paper Example

In this experiment we will investigate the various properties of equilibrium using a qualitative perspective.  Equilibrium is when the rate of the forward reaction is equal to the rate of the reverse reaction. There are four chemical systems that will be analyzed in this lab; acid-base reactions, soluble and insoluble salts, and complex ions.  Each of these scenarios will demonstrate the properties of Le Châtelier’s Principle, and illustrate that when changes in a chemical system occur, the direction of the chemical reaction will shift to reestablish its equilibrium. The reestablished equilibrium will either shift to impact the products side (right, forward) or the reactants side (left, reverse) of the chemical system. Le Châtelier’s Principle is important because it allows us to anticipate how a chemical system will change in response to a specific condition. 

There are three conditions that cause a chemical system to adjust its equilibrium; changes in the concentration of chemicals on either side of the equation, an increase or decrease in temperature, and pressure change that is applied to the system.  Because reactions trend towards a state of equilibrium, when the concentration of products is increased, the chemical system will shift to the right to produce more reactant.  The opposite is true when the concentration of reactants is increased; the chemical system will shift to the left to produce more product.   

Temperature also acts as either a product or a reactant in a chemical system and can cause changes to the equilibrium.  In an exothermic reaction, heat is considered to be a product. This causes the system to shift to the left side of the equation, while lowering the temperature causes the system to shift to the right.  In an endothermic reaction, heat is considered to be a reactant. This causes the system to shift to the products side of the equation, while lowering the temperature causes the system to shift to the reactants side of the equation.  

The third condition that impacts the equilibrium of a chemical system is changes in the pressure applied to a chemical system.  When pressure on the system is decreased, the chemical system shifts to the side of the equation with more moles.  When the pressure on the system is increased, the chemical system shifts to the side of the equation with less moles.  Pressure changes primarily effect gaseous reactions. 

Experiment 6 involves mixing specific pairs of chemical solutions or solutes together and describing how changes in the chemical reaction occurred. The pH of the solution will be indicated with a pH indicator, such as thymol blue, phenolphthalein, or methyl orange in order to visually illustrate what direction the equation moves towards.  Each of the four chemical systems will also be subjected to changes in temperature, to determine whether or not a system is endothermic or exothermic.  While changes in pressure also cause shifts in the direction of a gaseous chemical system, in this experiment we will only be observing how liquids, aqueous solutions, and solids impact equilibrium.