Seminar_5
1.
2.
3.
4.
A Review of Strong Electrolytes
The Autoionization of Water.
Polyprotic Acids.
Salts that Contain Small, Highly Charged Cations.
TEST – 5_ Acids and bases.
Be prepared to answer!




The specification of acidity and basicity of acids and bases.
The dissociation of Strong Electrolytes (acids and bases).
The definition of constant of dissociation.
Calculation of concentrations of Ions, calculation of Ka and pKa from equilibrium concentrations.
Aqueous solutions are very important. Nearly three-fourths of the earth’s surface is covered with water. Enormous
numbers of chemical reactions occur in the oceans and smaller bodies of water. Plant and animal fluids are mostly
water. Life processes (chemical reactions) of all plants and animals occur in aqueous solutions or in contact with
water. Before we were born, all of us developed in sacs filled with aqueous solutions, which protected and helped
nurture us until we had developed to the point that we could live in the atmosphere.
A REVIEW OF STRONG ELECTROLYTES
Water-soluble compounds may be classified as either electrolytes or nonelectrolytes. Electrolytes are compounds
that ionize (or dissociate into their constituent ions) to produce aqueous solutions that conduct an electric current.
Nonelectrolytes exist as molecules in aqueous solution, and such solutions do not conduct an electric current.
Strong electrolytes are ionized or dissociated completely, or very nearly completely, in dilute aqueous solutions.
Strong electrolytes include strong acids, strong bases, and most soluble salts.
Some strong acids and strong bases are listed in Table. Concentrations of ions in aqueous solutions of strong
electrolytes can be calculated directly from the molarity of the strong electrolyte, as the following example
illustrates.
Some Strong Acids and Strong Bases
Strong Acids
HCl, HNO3, HBr, HClO4, HI, (HClO3)*, H2SO4
Strong Bases
LiOH, NaOH, KOH, Ca(OH)2, RbOH, Sr(OH)2, CsOH, Ba(OH)2
*Chloric acid, HClO3, is sometimes not included in a list of strong acids since it is not commonly encountered.
However, its anion is much more common.
EXAMPLES
CALCULATION OF CONCENTRATIONS OF IONS
Calculate the molar concentrations of Ba2+ and OH― ions in 0.030 M barium hydroxide.
Plan
Write the equation for the dissociation of Ba(OH)2, and construct the reaction summary.
Ba(OH)2 is a strong base that is completely dissociated.
Solution
From the equation for the dissociation of barium hydroxide, we see that one mole of Ba(OH)2
produces one mole of Ba2+ ions and two moles of OH― ions.