5 Steps to a 5 AP Chemistry

232  Step 4. Review the Knowledge You Need to Score High

Ionization Constants:

HCOOH Ka = 1.8 × 10 −^4

CH 3 NH 2 Kb=4.4 × 10 −^4

H 3 PO 2 Ka1= 3 × 10 −^2

Ka2=1.7 × 10 -7

4. A solution with an initial KCOOH concentra-
   tion of 1 M, and an initial K 2 HPO 2 concentra-
   tion of 1 M.


5. A solution with an initial H 3 PO 2 concentration of
   1 M, and an initial KH 2 PO 2 concentration of 1 M.


6. A solution with an initial CH 3 NH 2 concentration
   of 1 M, and an initial CH 3 NH 3 Cl concentration
   of 1 M.


7. A solution of a weak base is titrated with a solu-
   tion of a standard strong acid. The progress of the
   titration is followed with a pH meter. Which of
   the following observations would occur?
   (A) The pH of the solution gradually decreases
   throughout the experiment.
   (B) Initially the pH of the solution drops slowly,
   and then it drops much more rapidly.
   (C) At the equivalence point the pH is 7.
   (D) After the equivalence point, the pH becomes
   constant because this is the buffer region.
   (E) The pOH at the equivalence point equals the
   pKbof the base.


8. What is the ionization constant, Ka, for a weak
   monoprotic acid if a 0.30-molar solution has a
   pH of 4.0?
   (A) 9.7 × 10 −^10
   (B) 4.7 × 10 −^2
   (C) 1.7 × 10 −^6
   (D) 3.0 × 10 −^4
   (E) 3.3 × 10 −^8


9. Phenol, C 6 H 5 OH, has Ka=1.0 × 10 −^10. What is
   the pH of a 0.010 M solution of phenol?
   (A) between 3 and 7
   (B) 10
   (C) 2
   (D) between 7 and 10
   (E) 7

10.You are given equimolar solutions of each of the

following. Which has the lowest pH?

(A) NH 4 Cl

(B) NaCl

(C) K 3 PO 4

(D) Na 2 CO 3

(E) KNO 3

11.When sodium nitrite is dissolved in water

(A) the solution is acidic because of hydrolysis of

the sodium ion

(B) the solution is neutral

(C) the solution is basic because of hydrolysis

of the sodium ion

(D) the solution is acidic because of hydrolysis

of the NO 2 −ion

(E) the solution is basic because of hydrolysis

of the NO 2 −ion

Questions 12–15 refer to the following aqueous

solutions. All concentrations are 1 M.

(A) H 2 C 2 O 4 (oxalic acid) and KHC 2 O 4 (potas-

sium hydrogen oxalate)

(B) KNO 3 (potassium nitrate) and HNO 3 (nitric acid)

(C) NH 3 (ammonia) and NH 4 NO 3 (ammonium

nitrate)

(D) C 2 H 5 NH 2 (ethylamine) and KOH (potas-

sium hydroxide)

(E) CH 3 NH 2 (methylamine) and HC 2 H 3 O 2

(acetic acid)

12.The most acidic solution (lowest pH)

13.The solution with a pH nearest 7

14.A buffer with a pH > 7

15.A buffer with a pH < 7

16.Determine the OH−(aq) concentration in 1.0 M

aniline (C 6 H 5 NH 2 ) solution. (Kbfor aniline is

4.0 × 10 −^10 .)

(A) 2.0 × 10 −^5 M

(B) 4.0 × 10 −^10 M

(C) 3.0 × 10 −^6 M

(D) 5.0 × 10 −^7 M

(E) 1.0 × 100 M