Le Chaˆtelier’s Principle

 Le Chaˆtelier’s Principle

Jihyun Yoo

Part A: Changing Pressure

Record the initial color of the carbonated beverage with the indicator added.

- The initial color of the carbonated beverage with the indicator added was light yellow.

When pulling the plunger back, brief describe your observations.

- It turned slightly green and bubbles were formed, when the plunger was pulled back.

How can these observations be explained in term of Le Cha^telier's Principle?

- The pressure decreases and the volume increases when the plunger is pulled back. In order to reach equilibrium, the solution and reaction shifts to favor much more moles of gas. Therefore, the products of the reaction made bubbles which is caused by CO2 outages and increase of pH. All of theses factors lead the solution turns green.

When depressing the plunger in, briefly describe your observations.

- When we depressed the plunger in, the solution turns yellow and the previous bubbles disappear.

How can these observations be explained in terms of Le Cha^telier's Principle?

- Based on the Le Chatelier Principle, when th epressure increases and the volume decreases, which makes the reaction favors the side of the reactants because of fewer moles of gas. Then, the bubbles disappear and carbon dioxide would be regained, which consequently decrease pH and the color would turn yellow. 

Part B: Changing Concentrations

Report your observations when adding HCO-3 to the carbonated beverage

- Adding HCO3- makes the solution in to blue and HCO3- dissolves directly

How can these observations be explained in terms of Le Chatelier's Principle?

- Putting HCO3- increases reactants of this chemical reaction that favors the side of the products and the overall reaction shifts to right. Therefore, it increases pH which turns the color blue. 

Part C: Changing Temperature

What is the initial temperature of the salt solution? 

- 21C

What are your observations of this solution at this temperature? 

- In this temperature, salt was observed in the water. Moreover, when we put laser light on it, the light was more diffracted than with just PI water. 

What is the highest temperature your solution reached? 

- 65C

What are your observations of this solution at this temperature? 

- In this temperature, all salts were dissolved so the laser was going through the solution without showing any diffraction.

What is the lowest temperature your solution reached? 

- 6.2C

What are your observations of this solution at this temperature? 

- In this colder temperature, more salts wer condensed again and therefore the laser diffracted significantly

Discuss any differences/similarities that you observed between the solutions. Be sure to discuss the light scattering events using the laser as well your physical observations. 

- In the high temperature, the salt was relatively dissolved so that the light directly passed through any diffraction. Otherwise, in colder temperature, the salt was condensed which made the light got diffracted.

How can these observations be explained in terms of Le Chaˆtelier’s Principle? 

- When heat is added to the reaction, there would be an excess of reactants and therefore the overall reaction to the side of products. Then, the salt got dissolved which allows light passing through without any diffraction. Otherwise, when the reaction is put in color temperature, it lowers the reactants which makes the reaction goes to reactants' side. Therefore, the salt would be made and the laser light might pass the solution with diffraction. 

Find a solubility vs. temperature curve for KCl (s). Sketch a graph of this reference curve. Does this curve agree or disagree with your experimental observations? Briefly explain.

 

Beyond the Lab Bench

Ammonia NH3 is a common chemical fertilizer and it is produced from the exothermic Haber process at 298 K.

N2(g) + 3H2(g) $ 2NH3(g) + heat Keq = 6.8x105 

If nitrogen or hydrogen are added to this equilibrated system, the reaction will shift toward the products according to Le Chaˆtelier’s Principle, thereby producing ammonia (HOORAY!) and heat. Ironically, as the temperature of the system increases, the reaction will shift back toward the reactants (OH NO!).

One might consider increasing the pressure to drive the reaction toward the products. However, the same thing will happen: a release of heat will lead to an increased temperature and the reaction will shift back toward the reactants.

Give the complexity of the Haber equilibrium, the community working on this problem have not achieved a production yield of ammonia above 15%. However, if we could improve the yield of ammonia, we could produce succulent fertilizer to adequately address food needs around the world. 

In order to address this issue, I can give some changes to each part of the reaction which makes the reaction goes to products. First of all, I can make pressure of the reaction increased and this would result the reaction goes to the products. Moreover, by keeping the fertilizer in cold temperature, it can prevent the reaction goes o the left side. All of these factors can make the reaction much more shower some in that case we can put some enzymes to catalyze the etude reaction.