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Chemistry 12
Le Châtelier’s Principle Assignment (Virtual Lab) /46 updated: Apr 2015
Outcomes:
explain how different factors affect solubility, using the concept of equilibrium (323-5)
analyze and describe examples where scientific understanding was enhanced or revised as a result of the invention of a technology (116-2)
analyze and describe examples where technologies were developed based on scientific understanding (116-4)
When you are done you must submit: completed pre-lab questions, results for each experiment (see attached observations sheets) and the completed post-lab questions.
Procedure:
1. Go to: Le Chatelier Virtual Lab on my website
2. Click on the link prelab on the web page and answer the questions using your notes on Le Chatelier’s Principle. Do only 1 and 2.
3. When finished the pre-lab activities, click on experiment.
4. Under preliminary items, click on General comments about the experiment. Read up on The Experiment. Hit the back button and then click on An example. Read up on it and then click Try one out.
5. Try out the example. Make a mental note of how the changes are described and portrayed.
6. Go back to the experiment page.
7. Click on the I. Cobalt System.
8. Write the equilibrium equation for the system (see attached observations sheets).
9. Try each stress factor and describe what happens (see attached observations sheets and the helpful hints below).
10. Repeat #8 and #9 with the III. Iron Thiocyanate System.
11. Repeat #8 and #9 with the IV. Chromate System.
12. Go back, click on and answer Post-lab questions 2,3 and 4.
Information for completing observation chart- In these experiments, you will be shown a series of equilibrium systems and asked to apply certain "stresses" to the systems. The results of applying the stress will then be shown to you. For each system, on the observation chart record:
(a) The name of the equilibrium system and the chemical equilibrium equation. Be sure to include all of the information provided about the system (Notes).
(b) Your observations; This means a colour change, a precipitate formed or some like statement. For example, "the red solution turned green". Do not use this part to state what chemical change occurred. For example, you should not say "more cobalt ion was formed".
(c) What you think happened chemically; State what chemical reaction occurred or species was formed that resulted in your observation. For example, "by adding chloride ion to the solution it shifted the equilibrium to the left which caused more CoCl4-2 ion to be formed. Since this ion is blue, the solution became more blue."
(d) What happens to the value of K? Indicate why the value of K increased, decreased or remained the same.