Experiment 15: Equilibrium Studies
Experiment 15
Title:
Equilibrium studies
Objective:
1. To study the effect of concentration and temperature changes on equilibrium.
2. To predict the direction of the net reaction in an equilibrium system by Le Chatelier’s principle.
Results:
Part 1 (a): Effect of temperature changes on equilibrium
Cu(NO3)2 (aq) Cu(NO3)2 (s)
The color of the solution = dark blue with precipitate
When placed in water bath 60oC
When placed in ice bath
The level of the solid
Decreases
Increases
Color of the solution
Dark blue with precipitate
Dark blue with precipitate
Part 1 (b): Investigate the aqueous equilibrium of a cobalt complex
[Co(H2O)6]2+ + 4Cl- [CoCl4]2- + 6H2O
Original color of the solution
Pink
Color when placed in water bath
Purplish blue
Color when placed in ice bath
Pinkish
Part 2 (a): Effect of concentration changes on equilibrium
2CrO42- + 2H+ Cr2O72- + H2O
Original color of potassium dichromate
Orange
Original color of potassium chromate
Yellow
Color after adding HCl to potassium chromate
Dark yellow
Color after adding NaOH to potassium chromate
Yellow
Color after adding back HCl to potassium chromate
Remains as yellow
Part 2 (b): Thymolphthalein equilibrium
Hln H+ + ln-
Color of the solution changes from blue to colorless
Time taken = 36.1s
Part 2 (c): Ammonium ion / ammonium equilibrium
NH3 + H2O NH4+ + OH-
Initial color of NH3
Colorless
Color after adding phenolphthalein
Purple color
Color after adding NH4Cl
Colorless
Questions and Answers:
1) Write down the equilibrium constant expression for the following reaction:
[Co(H2O)6]2+ (aq) + 4Cl- (aq) [CoCl4]2- (aq) + 6H2O (l)
In which direction will the equilibrium shift if you (a) increase the concentration of [Co(H2O)6]2+ and b) decrease the
Title:
Equilibrium studies
Objective:
1. To study the effect of concentration and temperature changes on equilibrium.
2. To predict the direction of the net reaction in an equilibrium system by Le Chatelier’s principle.
Results:
Part 1 (a): Effect of temperature changes on equilibrium
Cu(NO3)2 (aq) Cu(NO3)2 (s)
The color of the solution = dark blue with precipitate
When placed in water bath 60oC
When placed in ice bath
The level of the solid
Decreases
Increases
Color of the solution
Dark blue with precipitate
Dark blue with precipitate
Part 1 (b): Investigate the aqueous equilibrium of a cobalt complex
[Co(H2O)6]2+ + 4Cl- [CoCl4]2- + 6H2O
Original color of the solution
Pink
Color when placed in water bath
Purplish blue
Color when placed in ice bath
Pinkish
Part 2 (a): Effect of concentration changes on equilibrium
2CrO42- + 2H+ Cr2O72- + H2O
Original color of potassium dichromate
Orange
Original color of potassium chromate
Yellow
Color after adding HCl to potassium chromate
Dark yellow
Color after adding NaOH to potassium chromate
Yellow
Color after adding back HCl to potassium chromate
Remains as yellow
Part 2 (b): Thymolphthalein equilibrium
Hln H+ + ln-
Color of the solution changes from blue to colorless
Time taken = 36.1s
Part 2 (c): Ammonium ion / ammonium equilibrium
NH3 + H2O NH4+ + OH-
Initial color of NH3
Colorless
Color after adding phenolphthalein
Purple color
Color after adding NH4Cl
Colorless
Questions and Answers:
1) Write down the equilibrium constant expression for the following reaction:
[Co(H2O)6]2+ (aq) + 4Cl- (aq) [CoCl4]2- (aq) + 6H2O (l)
In which direction will the equilibrium shift if you (a) increase the concentration of [Co(H2O)6]2+ and b) decrease the