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Answers to Problems of the A Groups
(f) Fe
2+ + H 2 S + 2OH- -» FeS + 2H 2 O
One of the products (FeS) is insoluble, and the other (H 2 O) is only slightly
ionized
(g) NH 4
+ + OH- -» NH 3 + H 2 O
One of the products (NH 3 ) is a gas, the other (H 2 O) is slightly ionized
(h) Br- + H 3 PO 4 (conc'd) -> HBr + H 2 PO 4 -
One of the products (HBr) is a gas that evolves easily on warming
(i) 3CuS + 8H
+ + 2NO 3 - -* 3Cu
2+ + 3S + 2NO + 4H 2 O
An electron-transfer reaction for which the cell potential is positive Also, S is a
solid and NO is a gas
0) Ag(NH 3 ) 2
+ + r -» Agl + 2NH 3
Agl is more insoluble than Ag(NH 3 ) 2
f is unionized, and excess I~ helps shift the
equilibrium
3 (a) Pb
2+ + 2C1- -» PbCl 2 |
(b) NR
(c) 2Ag
+ + H 2 S -> Ag 2 S| + 2H
+
(d) 3Cd + 2H
+ + 2H 2 P0 4 - ->• Cd 3 (PO 4 ) 2 j + 3H 2 t
(e) BaCO 3 + 2H
+ -> Ba
2+ + H 2 O + CO 2 |
(f) NR
(g) Ba 3 (PO 4 ) 2 + 4H+ -> 3Ba
2+ + 2H 2 PO 4 -
(h) A1
3+ + 3NH 3 + 3H 2 O -> A1(OH) 3 | + 3NH 4
+
(i) Fe(OH) 3 + 3H+ -» Fe
3+ + 3H 2 O
H 2 O
Cl -> AgCll + HC 2 H 3 O 2
(q) Fe + Cu
2+ -» Fe
2+ + Cu
(r) NR
(s) 2MnO 4 - + 5H 3 AsO 3 + 6H
+ -> 2Mn
2+ + 5H 3 AsO 4 + 3H 2 O
(t) NR
(u) Ba
2+ + SOr -> BaSO 4 |
(v) ZnS + 2H
+ -» Zn
2+ + H 2 St
(w) Zn
2+ + S
2 ~ -» ZnSj
(x) C1 2 + 2Br~ -^ 2C1- + Br 2
(y) C1O 3 - + 6r + 6H
+ -» Cl- + 3I 2 + 3H 2 O
(z) NR
4 (a) Mix solutions of Pb(NO.,) 2 and Na 2 SO 4 and filter off precipitate
Pb
2+ + SOr -> PbSO 4 |
(b) Neutralize KOH with HC 2 H 3 O 2 , then evaporate off water
K
+ + OH + HC 2 H 3 O 2 -* K
+ + C 2 H 3 O 2 - + H 2 O
(c) Pass H 2 S gas into a dilute Cd(NO 3 ) 2 solution, and filter off CdS
Cd" + H 2 S -* CdS| + 2H
+
0) NR
(k) NR
(1) CuO
(m) NH 3 -
(n) NR
(o) NR
(P) Ag
+ -f
f 2H
+ -> Cu
2
i- H+ -H> NH 4
+
C 2 H 3 0 2 - + I