In-Class Group Activity #7 (Chem 101, Summer 2006)
Name ___________________________________
1. A Brønstead-Lowry _______________ donates H+ and a Brønstead-Lowry
_______________ accepts H+.
2. Give the conjugate base for each of the following Brønstead-Lowry acids:
a) HI
b) H2SO4
c) HCO3-
d) H2O
3. Give the conjugate acid for each of the following Brønstead-Lowry bases:
a) H2PO4-
b) NH3
4. For the following reaction:
c) OH-
d) H2O
NH3 + H2O  NH4+ + OH-
a) Identify which reactant is the acid and which is the base.
b) Identify the conjugate acid and conjugate base.
c) Write the Kb expression for the reaction.
d) Does the equilibrium favor reactants or products (Kb of NH3 = 1.8 x 10-5) ?
5. Since H2O can act as either a weak acid or a weak base, it can react with itself.
a) Write a balanced chemical equation for the reaction.
b) Does the equilibrium favor reactants or products?
c) What is Kw (write the expression and give the value)?
d) What is the concentration of OH- in pure water?
6. Consider the following two reactions:
A.
HCl + H2O  H3O+ + Cl-
B.
CH3CO2H + H2O  CH3CO2- + H3O+
a) Which reaction involves a strong acid, and which one a weak acid?
b) If 1.0 g of HCl is dissolved in H2O to a total volume of 250 mL, what is the pH of the
solution?
c) Write the Ka expression for reaction B.
d) What would you add to reaction B to make a buffer?
e) If the Ka for acetic acid (CH3CO2H) is 1.8 x 10-5, what is the pH of a buffer solution
prepared from 1.2 M CH3CO2H and 0.90 M CH3CO2- ?
7. What is the pH of a solution that has an OH- concentration of 1.0 x 10-3 M?
8. Complete and balance the following reactions:
a) Ca + HNO3 
b) KHCO3 + HCl 
c) CH3CO2H + NaOH 
9. State whether each of the following salts would make a neutral, basic or acidic
solution when dissolved in water. If the solution would be basic or acidic, write the
equation for the reaction that causes the pH change:
a) Na2SO4 (comes from NaOH + H2SO4)
b) NH4Br (comes from NH3 + HBr)
c) KCH3CO2 (comes from KOH + CH3CO2H)
10. A phosphate buffer is made by dissolving H3PO4 and NaH2PO4 in water.
a) Write the equation that shows how the buffer would neutralize a small amount of
added HCl (remember HCl + H2O  H3O+ + Cl-):
b) Write the equation that shows how the buffer would neutralize a small amount of
added NaOH (remember NaOH  Na+ + OH-):