Le Chatelier’s Principle

In this experiment, we determined the effect of a change on a system at equilibrium and correlated that to Le Chatelier’s Principle.

Introduction
Le Chatelier’s Principle says that when a system at equilibrium is put under stress, it will correct itself to relieve the stress and reestablish equilibrium. Equilibrium can be defined in a chemical reaction as when reactants are made into products at the same rate as products revert to reactants. A chemical system at equilibrium can undergo a change in concentration, temperature, volume, or partial pressure. According to Le Chatelier’s Principle, these changes can shift and a new equilibrium will be established. The concept is also used to increase the yield of reactions. By changing concentration, temperature, volume, or partial pressure, we can increase or decrease the yield of products.

Methods
This experiment was completed in two parts:

Part I

We prepared an ice water bath by partially filling a 50-ml beaker with tap water and crushed ice. It was set aside Next, we prepared a hot water bath and set it aside 5 drops of 2.0 M magnesium chloride was added to wells C1 and C2 of a 24-well plate. 10 drops were added to wells C3 and C4. 1 drop of phenolphthalein was added to wells C1, C2, C3, and C4 and stirred 5 drops of 1.0 M NaOH, sodium hydroxide solution, was added to wells C1, C2, C3, and C4. Solution was stirred and observations were recorded 1 drop of 6.0 M HCl, hydrochloric acid solution, was added to well C1. Observations were recorded We continued to add HCl drop-by-drop to well C1 until a color change was observed 1 drop of 0.15 M Na2EDTA was added to well C2. Observations were recorded.

Na2EDTA was continuosly added to well C2 until a color change was observed An empty pipet was labeled “C3” and we squeezed the pippette’s bulb and placed it in well C3’s solution and carefully sucked up all the mixture from the well into the bulb The pipet bulb was placed in the hot water bath and then in the water bath with the spoon handle outside of the beaker so as to not obstruct observations Steps 9 and 10 were repeated with a second pipet filled with the mixture from well C4. This pipet was also placed in the cold water bath As the temperature of the mixtures in the pipets changed, oberservations were recorded After about 10 minutes, we exchanged the pipets in the baths Finally, we disposed of the solutions and cleaned out the pipets

Part II

1. A test tube was marked and silver nitrate was added to the mark near the bottom 1 drop of NaCl was added to the test tube. The test tube was then placed on ice for a minute. Results were recorded The test tube was transferred, using a test tube holder, to the hot water bath prepared in Part I and gently agitated for 1–2 minutes. Results were recorded