Investigating Chemical Equilibria essays

Investigating Chemical Equilibria essays The aim of this experiment is to study the effect of concentration changes on equilibria. In some chemical systems the energies of the reactants and the products are of a similar order of magnitude so that the reaction is reversible, that is, it can take place in either direction. If such a system is established in a closed vessel, so that no gases could escape, then a chemical equilibrium is established. The forward and the reversible reaction have the same rate. So, if for example we take the reversible reaction A+B © C+D, then the initially forward reaction occurs rapidly, but as the concentration of the reactants falls, the rate decreases. The reverse reaction initially cannot occur at all, but as the products start to form, its rate increases. Consequently, the rate of the two reactions becomes equal, the concentrations reach constant values and the equilibrium is established. There are conditions, such as the temperature, the pressure and the concentration. According to Le Chatelier ¡s principle,  ¡if a change is made to the conditions of a chemical equilibrium, then the position of a chemical equilibrium will readjust so as to minimise the change made ¡. If the concentration of one species is changed, then the position of the equilibrium will shift to the opposite side. A change in pressure affects only the gaseous molecules. If pressure is increased, then the equilibrium will shift to the side where the most gaseous molecules exist, whereas if pressure is decreased, the equilibrium will shift to the side where the least gaseous molecules exist. Temperature is the only factor that by changing it, the equilibrium constant kc is affected. If temperature is increased, the endothermic reaction is favored, whereas, if temperature is decreased, the exothermic reaction is favored. In this experiment we will investigate, the change in equilibrium that will take place when the concentration is altered. We will d...