1
What salts yield neutral solutions?
Cations from strong bases:
• Alkali metal cations of group 1A (Li+, Na+, K+)
• Alkaline earth metal cations of group 2A (Mg2+, Ca2+,
Sr2+, Ba2+), except for Be2+
2. Anions from strong monoprotic acids:
• Cl–, Br–, I–, NO3–, and CIO4–
What salts yield acidic solutions?
Salts such as NH4Cl that are derived from a weak
base (NH3) and a strong acid (HCl) yield acidic solutions.
What salts yield basic solutions?
Salts such as NaCN that are derived from a strong base (NaOH) and a weak acid (HCN) yield basic solutions.
What is the common ion effect?
The shift in the position of an equilibrium
on addition of a substance that provides an ion in common with one of the ions already involved in the equilibrium
What is a buffer solution
A solution that contains a weak acid and
its conjugate base and resists drastic changes in pH
Calculate the pH at 25°C of a 0.002 M Ca(OH)2 solution and determine if the solution is acidic, basic, or neutral.
11.6, basic
What happens if Ka>Kb, if Ka<Kb, and Ka=Kb?
Ka > Kb: The solution will contain an excess of H3O+ ions (pH < 7).
• Ka < Kb: The solution will contain an excess of OH– ions (pH > 7).
• Ka ≈ Kb: The solution will contain approximately equal concentrations of H3O+ and OH– ions (pH ≈ 7).
Which of the following could act as a Lewis Base? a)NH3 b)BF3 c)Al3+ d)Fe(NO3)3
Both A and B
A 50.0 mL sample of 0.150 M HCl is titrated with 0.300 M NaOH. Calculate the volume of NaOH at the equivalence point.
25 mL
In strong bases what happens to the molecules
practically all
molecules are dissociated into
OH– or accept H’s
MgCl2 salts is acidic, basic, or neutral
MgCl2 is a salt of a strong acid (HCl) and a strong base (Mg(OH)2). Therefore, it will not hydrolyze, meaning it will not react with water. As a result, a solution of MgCl2 will be neutral (pH = 7) at 25°C. This is because neither the cation (Mg2+) nor the anion (Cl-) will react with water to change the pH. So, a solution of MgCl2 salts is neutral.
Calculate the pH at 25°C of a 0.0020 M Ba(OH)2 solution and determine if the solution is acidic, basic, or neutral
12.7 basic
Calculate the pH at 25°C of a 0.0010 M Ca(OH)2 solution and determine if the solution is acidic, basic, or neutral.
12, basic
Calculate the pH at 25°C of a 0.0018 M Mg(OH)2 solution and determine if the solution is acidic, basic, or neutral
12.26
Calculate the pH of a 0.200 M (CH3)3N solution
11.74
When you go left to right on the periodic table what happens to the acidity and why?
The acidity of hydrated main-group cations increases from left to right in the periodic table as the metal ion charge increases and the metal ion size decreases
Calculate the pH of a 0.075 M CH3NH2(aq) solution. Kb = 4.38 x 10-4
11.26
What is the pH of a buffer that is 0.20 M HCN (pKa = 9.21) and 0.10 M KCN?
9.30
Calculate the pH of a 0.075 M NH4Cl solution
5.22
Calculate the pH of a 0.150 M C5H5N solution.
9.24
What is pH of solution with 1.2345 x 10-4 M Ca(OH)2 a strong base
10.39
pH of .5L buffer w/ .7 HCOOH Ka = 1.77x 10-4 and .5M sodium formate(HCOONa)
3.604