Mr. Bouyer
Day 1 | Day 2 | Day 3 | Day 4 | Lab | Skills Test

  • Name salts based on the acid from which they are formed.
  • Use the solubility rules to determine the solubility of any salt.
  • Calculate the solubility product constant for a reversible salt-forming reaction.
  • Describe the Common Ion Effect.

Salts:

crystalline compounds composed of the negative ion
of an acid and the positive ion of a base.


Neutralization: the reaction of a base and an acid to produce a salt and water.
sodium hydroxide + hydrochloric acid yields sodium chloride + water
While the reaction shown here usually comes to mind when salt production is mentioned, there are many reactions that produce salts. It is even possible to have salts that do not produce neutral solutions.

Salts can also be formed by the reaction of an acidic or basic anhydride with a corresponding base, acid, or anhydride.

Certain acids and bases react to produce only a partial neutralization. These reactions produce either acidic salts or basic salts.

Naming salts: the name of a salt is related to the name of the acid that forms it.
  • Binary acids produce salts ending with ide.
  • Ternary acids ending in ic produce salts ending with ate.
  • Ternary acids ending in ous produce salts ending with ite.
  • Any prefixes in the ternary acid remain in the salt name.
  • In naming acidic and basic salts, each ion in the salt is named separately.
    • Hydrogen is named immediately before the names of any negative ions.
      • A prefix is used to indicate more than one hydrogen.
    • Hydroxide is named immediately after the names of any positive ions.
      • The hydroxide is commonly placed in parenthesis.

material safety data sheetsExamples of Salts:

Day 2

One way of grouping and identifying salts is by their solubility in water.

A salt dissolved in water makes a solution.
You may want to review solutions.link to a local webpage 		Explore this Internet Website about Chemistry

For about 95% of all compounds, solubility in water increases with increasing temperature. Many compounds can have their solubility in water increased or decreased by the presence of another solute.

Solubilities can be broken into four general classes:

the key points to useful information on this page the key points to useful information on this page

Follow these general rules to predict the solubility of salts.

Solubility Rules:
  1. Salts of group 1 and ammonia are soluble.
  2. Acetates and nitrates are soluble.
  3. Binary compounds of group 17, except F, are soluble with metals,
    except Ag, Hg+, and Pb.
  4. All sulfates are soluble, except those of Ba, Sr, Pb, Ca, Ag, and Hg+ .
  5. Except for those in rule 1, carbonates, hydroxides, oxides, sulfides,
    and phosphates are insoluble.

 

Practice Problems:

Use the rules above to determine the solubility of the following salts. Give the number of the rule you used to determine the answer.

    1. AgNO3
    2. Ag2SO4
    3. HgCl2
    4. BaSO4
    5. CaCl2
    6. NH4OH
    7. PbCl4
    8. Mg(C2H3O2)2

    9. HgCl
    10. CaF2
    11. CuO
    12. AgI
    13. Al(OH)3
    14. Fe2(CO3)3
    15. CrPO4
    16. K2S

Day 3

Solubility Product Constant, Ksp

If solid silver bromide is placed in water and allowed to stand, it dissolves until an equilibrium exists between the undissolved solid and the ions in solution.
  • At room temperature, the Ksp of silver bromide is 5.01 X 10-13
  • Using the equilibrium constant expression, [Ag+] [Br -] = 5.01 X 10-13
  • The concentration of both ions are the same, [Ag+]2 = 5.01 X 10-13
  • The square root of 5.01X10-13 gives: [Ag+] = 7.08 X 10-7M,
    which is also the [Br -]

Common Ion Effect: The addition of a substance containing an ion already at equilibrium in a saturated solution will shift the equilibrium toward the undissolved substance. Another way to say this is that the addition of a common ion decreases the solubility of a substance in solution.

Practice Problems:
  1. Write the solubility product constant expression for these equations:
    1. PbI2 (cr) Pb+2 (aq) + 2I -1 (aq)
    2. Cu3(PO4)2 (cr) 3Cu+2 (aq) + 2PO4 -3 (aq)

  2. A saturated solution of PbI2 has a lead ion concentration of 1.21X10 -3M. What is the Ksp for PbI2 ?

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