(^84) › STEP 4. Review the Knowledge You Need to Score High
- A sample is tested for the presence of the Hg^2 +
ion. This ion, along with others, may be pre-
cipitated with chloride ion. If Hg^2 + is present in
the chloride precipitate, a black color will form
upon treatment with aqueous ammonia. The
balanced net ionic equation for the formation of
this black color is:
(A) Hg 2 Cl 2 + 2 NH 3 + 2 H 2 O → 2 Hg +
2 NH 4 + + 2 Cl- + 2 OH-
(B) Hg 2 Cl 2 + 2 NH 3 → Hg + HgNH 2 Cl +
NH 4 + + Cl-
(C) Hg 2 Cl 2 + 2 NH 4 + → 2 Hg + 2 NH 4 Cl
(D) Hg 2 Cl 2 + NH 4 + → 2 Hg + NH 4 Cl + Cl- - How many moles of Pb(NO 3 ) 2 must be added
to 0.10 L of a solution that is 1.0 M in MgCl 2
and 1.0 M in KCl to precipitate all the chloride
ion? The compound PbCl 2 precipitates.
(A) 1.0 mole
(B) 0.20 mole
(C) 0.50 mole
(D) 0.15 mole - When 50.0 mL of 1.0 M AgNO 3 is added to
50.0 mL of 0.50 M HCl, a precipitate of AgCl
forms. After the reaction is complete, what is the
concentration of silver ions in the solution?
(A) 0.50 M
(B) 0.0 M
(C) 1.0 M
(D) 0.25 M - A student mixes 50.0 mL of 0.10 M Pb(NO 3 ) 2
solution with 50.0 mL of 0.10 M KCl. A white
precipitate forms, and the concentration of the
chloride ion becomes very small. Which of the
following correctly places the concentrations of
the remaining ions in order of decreasing con-
centration?
(A) [NO 3 - ] > [Pb^2 +] > [K+]
(B) [NO 3 - ] > [K+] > [Pb^2 +]
(C) [K+] > [NO 3 - ] > [Pb^2 +]
(D) [Pb^2 +] > [NO 3 - ] > [K+]
13. A solution is prepared for qualitative analysis.
The solution contains the following ions: Co^2 +,
Pb^2 +, and Al^3 +. Which of the following will cause
no observable reaction?
(A) Dilute NH 3 (aq) is added.
(B) Dilute K 2 CrO 4 (aq) is added.
(C) Dilute HNO 3 (aq) is added.
(D) Dilute K 2 S(aq) is added.
14. Chlorine gas is bubbled through a colorless solu-
tion, and the solution turns reddish. Adding a
little methylene chloride to the solution extracts
the color into the methylene chloride layer.
Which of the following ions may be present in
the original solution?
(A) Cl-
(B) I-
(C) SO 42 -
(D) Br-
15. The addition of excess concentrated NaOH(aq)
to a 1.0 M (NH 4 ) 2 SO 4 solution will result in
which of the following observations?
(A) The solution becomes neutral.
(B) The formation of a brown precipitate takes
place.
(C) Nothing happens because the two solutions
are immiscible.
(D) The odor of ammonia will be detected.
16. C 4 H 11 N(l) + O 2 (g) → CO 2 (g) +
H 2 O(l) + ___ N 2 (g)
When the above equation is balanced, the lowest
whole number coefficient for CO 2 is:
(A) 4
(B) 16
(C) 27
(D) 22