Le' Chatelier's Principle

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  • Topic: Chemical reaction, Chemistry, Sodium chloride
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  • Published : November 24, 2012
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Purpose:

The purpose of this lab is to develop a deeper understanding of LeChatelier’s Principle by observing several systems at chemical equilibrium and interpreting the effects of varying concentrations and temperature. The principle states that if systems at equilibria are altered or disturbed in any form, the equilibria will shift to reduce the disturbing influence ( Catalyst, 186). In a 3 part experiment, we analyzed the outcome of changes in reactant and product concentrations, equilibrium involving sparingly soluble salts, and the effect of temperature on the equilibrium. In part 1 , we observed the shift in equilibria of two aqueous solutions of Copper and Ammonia then Nickel and Ammonia. In part 2, we focused on cobalt ions in the presence of chloride ions as well as the precipitation of silver nitrate and sodium carbonate. In the last part of the experiment we utilized a solution of Cobalt chloride and compared the color at room temperature and then again in a container of boiling water. Physical Data:

No physical Data was applicable to the experiment.

Chemical Equations:
Part i: Changes in Reactant or Product Concentrations
A.Copper and Nickel Ions

[Cu(H2O)4]2+ (aq) + 4NH3(aq) ←→ [Cu(NH3)4]2+(aq) + 4H2O(l) blue dark blue

[Ni(H2O)6]2+(aq) + 6NH3(aq) ←→ [Ni(NH3)6]2+(aq) + 6H2O(l) green pale violet

H+(aq) + NH3(aq) ←→ NH4 +(aq)

B. Cobalt Ions

[Co(H2O)6]2+(aq) + 4CL- (aq) ←→[CoCl4]2-(aq) + 6H2O(l)

Part ii: Equilibrium Involving Sparingly Soluble Salts

2AgNO3(aq) + Na2CO3(aq) ←→ Ag2CO3(s) + 2NaNO3(aq)

2Ag+(aq) + CO32-(aq)←→ Ag2CO3(s)
Net ionic equation ^

2H+(aq) + CO32-(aq) ←→ H2CO3(aq); H2CO3(aq) → CO2(g) + H2O(l)

Ag+(aq) + Cl-(aq)←→AgCl(s)

Ag+(aq) + 2NH3(aq) ←→ [Ag(NH3)2]+(aq)

I-(aq) + Ag+(aq) ←→ AgI(s)
Safety
Safety goggles are required to be worn throughout entire duration of the lab experiment. •Wear gloves, as the chemicals may cause serious damage to the skin skin. •Be sure to clean materials with soap and water before beginning any procedures. •When disposing wastes, be sure to do so in the appropriate receptacle. •Use precaution when handling all chemicals, careful not to inhale anything. Experimental Procedure and Observations

Part i: Changes in Reactant or Product Concentrations
A.Copper and Nickel Ions

Procedure

Copper

1.Place 1 mL of 0.1 M CuSO4 in a clean test tube.
2.Add 15 M NH3 drop wise until a color change occurs.
3.Mix the solution in the test tube as you add the NH3.
4.Add 1 M HCl drop wise while mixing the solution, until the color changes. Nickel

1.Place about 1 mL of 0.1 M NiCl2 in a clean test tube.
2.Add 15 M NH3 drop wise until a color change occurs.
3.Mix the solution in the test tube as you add the NH3.
4.Add 1 M HCl drop wise while mixing the solution, until the color changes.

Observations

Copper

1.The liquid is light blue in color.

2.The solution turned to royal blue.

3.Solution begins to slowly change to a more transparent blue.

4.We added 56 drops, the top of the solution remained royal blue as the bottom turned completely clear and colorless. After shaking it, it turned completely light blue. Nickel

1.The liquid is light/clear green in color.
2.The solution turned from green to blue to a lavender complex. 3.The solution turned to a clear lavender color.
4.The solution reverted back to clear green.

B. Cobalt Ions

Procedure

1.Place 0.5 mL of 1 M CoCl2 in a test tube.
2.Add 12 M HCl to test tube until a change is noticeable.
3.Slowly add water to the test tube while mixing.Observations

1.Exactly 10 drops are placed in the tube. The liquid is pale pink in color. 2.The solution turned to dark blue.

3.The solution slowly turns to purple, as little particles form on the bottom. A pale pink color began to form at...
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