Applications of Le Châtelier's Principle
(September 11 - 15, 2014)
**The purpose of this experiment was to visually observe the effects of how changing certain aspects of the reaction affected the observed equilibrium.
Part A: Effect of Concentration:
Two different temperature water baths were created, one at 65-70oC, the other ice, and set aside for Part B.
20 mL of potassium thiocyanate solution were poured into a petri dish. The initial color and all subsequent observations were recorded in the data table.
Three drops of iron (III) nitrate were added to different spots in the petri dish, and the resulting solution was swirled until the color was consistent.
Approximately ½ pea-sized sample of potassium thiocyanate crystals was added to one spot. After 30 seconds, the solution was mixed.
Approximately a ½ pea-sized sample of potassium nitrate crystals was added to one spot in the petri dish. After 30 seconds, this solution was again mixed.
About a ¼ pea-sized sample of sodium phosphate monobasic crystals were added to one spot in the petri dish. After 60 seconds, this solution was mixed.
One drop of iron (III) nitrate solution was added to the side of the petri dish, while a pea-sized amount of potassium thiocyanate crystals was added to a different spot. After 30 seconds, the solution was swirled to ensure the crystals fully dissolved and this final solution was saved for use in Part B.
Part B: Effect of Temperature:
The solution saved from Part A was divided evenly into two test tubes labelled 'A' and 'B'. Test tube A was kept as the control. Test tube B was placed into an ice water bath for three to five minutes and then compared to the control.
Test tube B was then placed into a hot water bath for two to three minutes and again compared to the control.
Activity A: Acid-Base Indicator Equilibrium
Approximately 2 ml of deionized water was added into a test tube with 5 drops of 0.04 % bromthymol blue.
Four drops of 0.1 M hydrochloric acid was added to the solution and mixed.
Four drops of 0.1 M sodium hydroxide was added to the solution and mixed.
After solution appeared to change back to original conditions.
Activity B: Formation of a copper complex ion.
5 mL of 0.2 M copper (II) sulfate was added to a test tube.
One Drop of ammonium hydroxide was added to 5 mL of copper (II) sulfate
Another drop of ammonium hydroxide was added to the solution
Two Drops of hydrochloric acid was added to the solution
Two Drops of ammonium hydroxide was added to the solution
Four drops of hydrochloric acid was added to the solution
Another 2 drops of hydrochloric was added to the solution
Activity C: Formation of a Cobalt Complex Ion.
2 mL of the cobalt chloride solution was added to three separate test tubes (A, B, and C).
1 mL of silver nitrate (milky white color) was added in test tube A
Three gains of calcium chloride was added to test tube B
1 mL of Hydrochloric Acid was added to test tube C
Activity D: Solubility of Carbon Dioxide:
Approximately 10 mL of fresh seltzer water has mixed with 20 drops of 0.04 % bromcresol green indicator. The initial color was compared to a pH chart.
The solution was drawn up into a syringe, the excess air squeezed out, and the syringe capped.
A vacuum was generated by pulling out the syringe, and the solution was shaken.
The solution was then compared against a color coded pH chart to determine any change.
Activity E: Solubility of Magnesium Hydroxide
10 mL of milk of magnesia was added to 50 mL or deionized water in a beaker with 5 - 10 drops of universal indicator solution. This mixture was placed on a magnetic stirrer, to ensure consistent mixing.
Eight drops of indicator fluid is added to 10 mL of milk of magnesia
The solution was placed in
Cobalt chloride solution is moderately toxic by ingestion. Iron...
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