Exam 3

Chemistry 112

Name:_________________

Show your work!

1. Label each specie as an acid or a base and write its conjugate

acid or base? Conjugate?

(A) (CH₃)₃N ____________ ____________________

(B) HOCN ____________ ____________________

(C) HI ____________ ____________________

(D) NH₂NH₃⁺ ____________ ____________________

2. What is the % ionization or dissociation for a .10 M solution of HC₇H₅O₂(aq)? K_a for HC₇H₅O₂ = 6.3 x 10⁻⁵.

3. A .25 M solution of a weak acid has a pH of 4.00. What is the K_a for the acid?

4. What is the……. of the aqueous solutions?

(A) pH of 0.0050 M H⁺

(B) pH of 10. M HNO₃

(C) pH of 0.050 M [NaOH]

(D) [H⁺] if pH = 3.45

5. A 0.050 M solution of aniline (C₆H₅NH₂) has a pH = 8.64, what is the K_b for aniline?

6. What is the pH of a solution of 0.15 M NH₄Cl(aq) ? K_b NH₃ = 1.8 x 10^–5.

7. What is the pH of 1.0 M H₂SO₄(aq). K_a2 = 0.012

Circle the:

(A) Weakest acid: H₂O or H₂Se

(The O-H bond is stronger than the Se-H bond)

(B) Strongest acid: HClO₃ or HClO₂

(C) Strongest acid C₆H₅COOH or C₅H₅OH

(D) Strongest base NO₃^– or NO₂^–

(E) Weakest base Cl^– or F^–

8. List from the strongest acid to the strongest base: HC₂H₃O₂, NaCl, NH₃, HCl, NaC₂H₃O₂

___________ ___________ ___________ ___________ ___________

Strongest acid strongest base