Page 149 - Theory and Problems of BEGINNING CHEMISTRY

138 NET IONIC EQUATIONS [CHAP. 9

9.7. Write a net ionic equation for the following overall equation:

Cr + 2Cr(NO 3 ) 3 −→ 3Cr(NO 3 ) 2
Ans. Cr + 3Cr 3+ −→ 3Cr 2+
Chromium ions appear on both sides of this equation, but they are not spectator ions since they are not
identical. One is a 3+ ion and the other is a 2+ ion. The neutral atom is different from both of these.

9.8. Write a net ionic equation for each of the following overall equations:
(a) HNO 3 + NaOH −→ NaNO 3 + H 2 O (d) HNO 3 + RbOH −→ RbNO 3 + H 2 O
(b) HCl + KOH −→ KCl + H 2 O (e) HClO 3 + KOH −→ KClO 3 + H 2 O
(c) HClO 4 + LiOH −→ LiClO 4 + H 2 O
Ans. In each case, the net ionic equation is
−
H + OH −→ H 2 O
+
9.9. Write a net ionic equation for each of the following overall equations:
(a) HClO 3 + LiOH −→ LiClO 3 + H 2 O
(b) HClO 3 + RbOH−→ RbClO 3 + H 2 O
Ans. In each case, the net ionic equation is
+
−
H + OH −→ H 2 O
9.10. Write a net ionic equation for each of the following overall equations:
(a)H 3 PO 4 + 3 NaOH −→ Na 3 PO 4 + 3H 2 O
(b) MgCO 3 (s) + CO 2 + H 2 O −→ Mg(HCO 3 ) 2
(c) KHCO 3 + NaOH −→ K 2 CO 3 + H 2 O
−
−
Ans. (a)H 3 PO 4 + 3OH −→ PO 4 3− + 3H 2 O (c) HCO 3 + OH −→ CO 3 2− + H 2 O
−
(b) MgCO 3 + CO 2 + H 2 O −→ Mg 2+ + 2 HCO 3 −
9.11. Write a net ionic equation for each of the following overall equations:
(d)2 Al + 3 HgCl 2 −→ 2 AlCl 3 + 3Hg
(a) 2 AgNO 3 + H 2 S −→ Ag 2 S(s) + 2 HNO 3
(e)Zn + FeCl 2 −→ ZnCl 2 + Fe
(b)Zn + 2 HCl −→ ZnCl 2 + H 2
(c)Cu + 2 AgNO 3 −→ Cu(NO 3 ) 2 + 2Ag
Ans. (a)2 Ag + H 2 S −→ Ag 2 S + 2H + (d)2 Al + 3Hg 2+ −→ 2Al 3+ + 3Hg
+
+
(b)Zn + 2H −→ Zn 2+ + H 2 (Note the overall charge balance.)
+
(c) Cu + 2Ag −→ Cu 2+ + 2Ag (e) Zn + Fe 2+ −→ Fe + Zn 2+
9.12. Write six more equations that can be represented by the net ionic equation of Example 9.1. Use the same
reactants that are used in the equations in Example 9.1

Ans. AgNO + KCl −→ KNO 3 + AgCl(s)
3
AgClO + NH 4 Cl −→ NH 4 ClO 3 + AgCl(s)
3
AgC H 3 O 2 + NaCl −→ NaC 2 H 3 O 2 + AgCl(s)
2
AgNO + NH 4 Cl −→ NH 4 NO 3 + AgCl(s)
3
AgClO + NaCl −→ NaClO 3 + AgCl(s)
3
AgC H 3 O 2 + KCl −→ KC 2 H 3 O 2 + AgCl(s)
2