SOLUBILITY EQUILIBRIA AND COMMON ION EFFECTS

Question 1

The solubility products Ksp’s are ______ in heterogeneous equilibria (i.e., between two different phases).

Answer 1

equilibrium constants

Question 2

If several ____ are present in a system, they all ____in the solution. If the salts contain a common ______, these salts contribute to the ______ of the common ion. Contributions from all salts must be included in the calculation of the concentration of the common ion.

Answer 2

• salts
• ionize
• cation or anion
• concentration

Question 3

The “_________” happens when the dissociation of a weak electrolyte is decreased by adding to the solution a strong electrolyte (i.e., a salt) that has an ion in common with the weak electrolyte. This may cause an imbalance in the equilibrium of the reaction.

Answer 3

Common Ion Effect

Question 4

According to _______, if an equilibrium becomes unbalanced, the reaction will shift to restore the balance.

Answer 4

Le Châtelier’s Principle

Question 5

If a common ion is added to a weak acid or weak base equilibrium, then the equilibrium will ______, in this case, the weak acid or base.

Answer 5

shift towards the reactants

Question 6

One way of predicting these concentration shifts is by ____ or _____.

Answer 6

observing the changes in color or formations of the precipitate

Question 7

13 Materials used in exp 5

Answer 7

• HCI,
• NaCl,
• K2CrO4,
• BaCl2,
• KSCN,
• NaOH,
• AgNO3,
• iron (III) chloride burette,
• test tubes,
• stopper,
• distilled water,
• spatula,
• dropper

Question 8

Two parts of the experiment 5?

Answer 8

• Solubility equilibria and common ion effects
• Complex ion equilibria and common ion effects

Question 9

3 sub-procedures under the Part I of Exp 5

Answer 9

A. NaCl and HCl
B. K2CrO4 solution and HCl
C. BaCl2 solution and K2CrO4

Question 10

In Exp 5.1-A:
* Obtain ___ mL of _____ solution in a test tube. Add ____ drops of concentrated HCI to the 5 mL solution of saturated NaCl solution. Record your observations.

Answer 10

• 5
• saturated sodium chloride
• 10-20

Question 11

In Exp 5.1-B:
1. Obtain __ mL of _____ solution in a test tube. Add ___ mL of distilled water and mix vigorously. Now add ____ dropwise (about one mL) and stir. Record your observations.
2. Add about __ of __ to the test tube containing the orange solution.

Answer 11

• 2
• 1.0 M K2CrO4
• 2
• 6.0 M HCI
• 1 mL
• 6.0 M NaOH

Question 12

In Exp 5.1-C:
1. Add a few drops of _____ to ____ of a ___.
2. Now add a few mL of ____ dropwise with stirring to the test tube containing the _______ (color) precipitate. Record your observations.

Answer 12

• 1.0 M K2CrO4
• 3 mL
• 0.10 M BaCl2
• 6.0 M HCI
• yellow

Question 13

In Exp 5.2:
1. Prepare a _____ by mixing ___ mL of ___ M iron (III) chloride and ___ mL of ____ KSCN solutions.

Answer 13

• stock sample solution
• 1
• 0.20
• 2
• 0.10 M

Question 14

In Exp 5.2:
2. Prepare __ (number) clean test tubes and label from ___. Add __ of stock solution in each test tube. ______ will be used as a standard to compare the color with the other test tubes.

Answer 14

• 5
• A-E
• 5 mL
• Test tube A

Question 15

In Exp 5.2:
* What do you add in Test tube B

Answer 15

add 0.5 mL of 0.20 M FeCl3 and stir

Question 16

In Exp 5.2:
* What do you add in Test tube C

Answer 16

add about 1 mL of KSCN solution and stir

Question 17

In Exp 5.2:
* What do you add in Test tube D

Answer 17

add few drops of 0.1 M NaOH and stir

Question 18

In Exp 5.2:
* What do you add in Test tube E

Answer 18

Add few drops of 0.10 M AgNO3 dropwise until changes become evident