352 ❯ STEP 5. Build Your Test-Taking ConfidenceHNN N NH NH HHNHDiazene TriazeneNTetrazeneNHNHH- Ammonia is the best-known nitrogen-hydrogen
compound; however, there are a number of other
nitrogen-hydrogen compounds, three of which
are in the above diagram. Which of these has the
longest average N-N bond length?
(A) N 2 H 2
(B) N 3 H 3
(C) N 4 H 4
(D) They are all the same. - The above equilibrium was established in a 1.00 L
container at a certain temperature. Once the system
came to equilibrium, it was found that the following
amounts of materials were present in the container:
(NH 4 ) 2 CO 3 = 8.00 moles, NH 3 = 4.00 moles,
CO 2 = 2.00 moles, and H 2 O = 2.00 moles.
Determine the value of Kc at this temperature.
(A) 8.00
(B) 64.0
(C) 4.00
(D) 32.0 - 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) Initially, the pH slowly decreases, then
there is a rapid decrease to give a pH below
7 at the equivalence point.
(B) The pH of the solution gradually decreases
throughout the experiment, and the pH at
the equivalence point is below 7.
(C) Initially, the pH slowly decreases, then
there is a rapid decrease to give a pH equal
to 7 at the equivalence point.
(D) Initially, the pH quickly decreases, then there
is a gradual decrease to the equivalence point
where the pOH equals the pKb of the base.
51. A student mixes 100.0 mL of a 0.10 M hydroflu-
oric acid, HF, solution with 50.0 mL of a 0.10 M
potassium hydroxide, KOH, solution. The Ka
for hydrofluoric acid is 6.8 × 10 -^4. Which of the
diagrams below best represents the species, other
than H 2 O, in the solution after the acid reacts
with the base?
(A)K+F K+F–(B)
K+ K+OH– F–(C)
K+ H FF H+F–(D)
H+K+F–F–GO ON TO THE NEXT PAGE21-Moore_PE02_p341-370.indd 352 31/05/18 1:54 pm