Chemical Equilibrium Lab

Chemical Equilirium

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DISCUSSION Chemical equilibrium and its different applications were studied in this experiment. The Le Chatelier’s principle, which is the main principle behind chemical equilibrium, states that, “If an external stress is applied to a system at equilibrium, the system adjusts in such a way that the stree is partially offset as the system reaches a new equilibrium position.”[1] The “stress” can be a change in concentration, volume, pressure, or temperature that disturbs the equilibrium
It is the Cu(OH)2, with the reaction,
(6) Cu2+(aq) + 2NH3(aq) + 2H2O(l) ⇌ Cu(OH)2(aq) + 2NH4+ (aq)
However, after NH3 was added in excess, a deep blue complex solution was formed, and the precipitate was dissolved. But upon the addition of HCl, the color of the solution returned to pale blue again. This is because the addition of H+ reacts with NH3 and forms NH4+ . This causes the reactant-favored shift of equilibrium. (7) H+(aq) + NH3(aq) → NH4+ It was also noticed that it took more drops of NH3 turn the solution to deep blue complex than the number of drops of HCl needed to turn the solution back to pale blue.
The Chromate - Dichromate equilibrium was also studied. In this part of experiment, the shifting of equilibrium was observed as the pH of the environment was changed. From yellow, chromate turned to orange (dichromate) as an acid, H2SO4 was added. The H2SO4 pushed the reaction to the right because more hydrogen ions were added. H2SO4 was used because it is a strong acid and it dissociates leaving H+ behind. NaOH was also added to chromate in another spot plate well. However, it did not show any changes because as shown in equation 8, the addition of OH- only pushes the reaction to produce more chromate
Test tube 1 is the control, with is light orange in color. In test tube two, more FeCl3 were added which resulted to a change in color—from light orange to dark orange. Also, in test tube 3, more amount of the reactant KSCN was added and it also resulted to a dark orange solution. It can be inferred that the equilibrium shifted to the right, which is product favored because of the additional amount of reactants added. On the other hand, NaCl was added in test tube 4, which produced a light orange solution. The equilibrium apparently shifted to the left because of the added Cl- which adds to the Cl- in the dissociated