chapter 6: chemical reactions. determine if a compound is soluble
TRANSCRIPT
Aqueous Solutions
A compound is soluble in a particular liquid if it dissolves in that liquid.
A compound is insoluble if it does not dissolve in the liquid.
Aqueous Solutions
An aqueous solution is a homogeneous mixture of a substance with water. When ionic compounds dissolve in water, they usually dissociate into their component ions.
Aqueous Solutions
A sodium chloride solution, NaCl(aq), does not contain any NaCl units. Only dissolved Na+ ions and Cl− ions are present.
Substances (such as NaCl) that completely dissociate into ions in solution are called strong electrolytes.
Aqueous Solutions
Pure water does not conduct electricity.
Ions in a sodium chloride solution conduct electricity, causing the bulb to light.
Aqueous Solutions
AgNO3(aq) is a strong electrolyte solution.
When compounds containing polyatomic ions such as NO3
− dissolve, the polyatomic ions dissolve as intact units.
Aqueous Solutions
Not all ionic compounds dissolve in water. AgCl does not dissolve in water. It does not dissolve into independent ions.
Solubility Rules
A compound is soluble in a particular liquid if it dissolves in that liquid; a compound is insoluble if it does not dissolve in the liquid.
For ionic compounds, empirical rules of solubility have been deduced from observations of many compounds.
Soluble Compounds
Exceptions
NO3-, C2H3O2
-
Li+,Na+, K+, NH4+
Cl-, Br-, I-Except those containing
Ag+, Hg22+, Pb2+
SO42-
Except those containing Ba2+, Ca2+, Pb2+,
Sr2+Will dissolve in water
Will NOT dissolvein water
Solubility Rules
For example: Ca(NO3)2 is soluble
LiBr is soluble
Hg2Cl2 is insoluble
CaSO4 is insoluble
Insoluble Compoun
dsExceptions
S2-
Except those containing Li+, Na+, K+, NH4
+ Ca2+, Ba2+, Sr2+
CO32-, PO4
3-Except those containing Li+, Na+, K+, NH4
+
OH-
Except those containing Li+, Na+, K+, NH4
+
Those containing Ca2+, Sr2+, Ba2+ are slightly soluble
Will dissolve in water
Will NOT dissolve in
water
Solubility Rules
For example: Al2S3 is insoluble
CaCO3 is insoluble
Pb(OH)2 is insoluble
K2S is soluble
Na3PO4 is soluble
NH4OH is soluble
Practice
Use the solubility rules to predict which of the following substances are likely to be soluble in water:
Aluminum nitrate
Magnesium chloride
Rubidium sulfate
Nickel (II) hydroxide
Lead (II) sulfide
Magnesium hydroxide
Iron (III) phosphate
Silver bromide