Lab Report on Le Chatelier's Principle

1361 words 6 pages
Castro, Lharize C.
Experiment # 1

I. Introduction: In this experiment, using Le Chatelier’s principle, we will observe several responses of a system at equilibrium to various changes in external conditions. The experiment aims to investigate two equilibrium systems: (a) cobalt complexes and (b) chromate-dichromate equilibrium and explain observations in light of the Le Chatelier’s principle.

II. Theory/Concepts: In 1884 the French chemist and engineer Henry-Louis Le Chatelier proposed one of the central concepts of chemical equilibria. Le Chatelier's principle can be stated as follows: A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium
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Temperature Effects CoCl2 + concentrated HCl at: | room temperature | no change in color (still red-violet) | cold temperature | red violet to light pink | hot temperature | red violet to dark violet |

VI. Interpretation of Results: Table 1 showed the change in color of the solutions due to the increase in concentration of one of the reactants on the opposite side of the reaction, causing the system to consume more reactant in order to regain its equilibrium. Table 2 showed that when HCl was added to chromate and dichromate solution, the concentration of H+ increased because of the H+ ions present in HCl causing a decrease in the concentration of K2CrO4 and K2Cr2O7. When Ba(NO3)2 was added to the solution K2Cr2O7, it reacted to form white precipitate and when added to K2CrO4 it causes the lightening in its color. Table 3 showed how changes in temperature affect the equilibrium of the solution by the incorporation of heat as a reactant or product. Through this, it can be determined whether there would be an increase or decrease of temperature that would favor the forward or reverse reaction by applying the same principle as with the concentration changes.

Picture A. Shows 6 test tubes with 2 ml of ethanol solution used