Name _____________________________________________ Date ____________________ Period ______
Weak Acid and Base Calculations
Solve the following problems. Show all work, including Ka/Kb expressions, with units. Round all answers to the correct number of significant figures.
1. The [H+] and [CNO-] of a 0.10 M solution of cyanic acid (HCNO) is found to be 0.0010 M at equilibrium. Calculate the
Ka for cyanic acid.
HCNO(aq) ↔ H+(aq) + CNO‐(aq)
#1 Answer:
2. For the reaction of hydrazine (N2H4) in water, Kb = 3.0 x 10-6. Calculate all concentrations at equilibrium and the pH of a
2.0 M solution of hydrazine in water.
H2NNH2(aq) ↔ H2NNH3+(aq) + OH-(aq)
#2 Answer:
[H2NNH2] =
[H2NNH3+] =
[OH-] =
pH =
3. Calculate the equilibrium concentrations of all species and the pH of a 0.350 M solution of HC2H3O2. Ka = 1.8 x 10-5
#3 Answer:
[HC2H3O2] =
[C2H3O2-] =
[H+] =
pH =
4. What are the equilibrium concentrations of all species and the pH of a 2.0 M solution of HF? Ka = 7.2 x 10-4
#4 Answer:
5. The Ka of HCN is 6.17 x 10-10. Find the equilibrium concentration of all species, the percent ionization, and the pH of
0.950 M solution of HCN.
#5 Answer:
6. A 0.250 M solution of HCOOH is 8.00% dissociated. Calculate the Ka, pH, and pOH at equilibrium.
#6 Answer:
Ka =
pH =
pOH =