Page 140 - Theory and Problems of BEGINNING CHEMISTRY

CHAP. 8] CHEMICAL EQUATIONS 129

(c)2 Al + 6 HCl −→ 2 AlCl 3 + 3H 2
(d) 2 HCl + Mg −→ MgCl + H 2
2
(e) SrCO 3 + 2 HClO 4 −→ Sr(ClO 4 ) 2 + CO 2 + H 2 O
(f )KC 2 H 3 O 2 + HBr −→ KBr + HC 2 H 3 O 2
(g)Ba(OH) 2 + H 3 PO 4 −→ BaHPO 4 + 2H 2 O
(h) 2 HCl + Na 3 PO 4 −→ 2 NaCl + NaH 2 PO 4

8.7. Write balanced equations for each of the following reactions:
(a) Sodium plus oxygen yields sodium peroxide.
(b) Mercury(II) oxide, when heated, yields mercury and oxygen.
(c) Carbon plus oxygen yields carbon monoxide.
(d ) Sulfur plus oxygen yields sulfur dioxide.
(e) Propane (C 3 H 8 ) plus oxygen yields carbon dioxide plus water.
(f ) Ethane (C 2 H 6 ) plus oxygen yields carbon monoxide plus water.
(g) Ethylene (C 2 H 4 ) plus oxygen yields carbon dioxide plus water.

Ans. (a)2 Na + O 2 −→ Na 2 O 2 (e) C 3 H 8 + 5O 2 −→ 3CO 2 + 4H 2 O
heat
(b) 2 HgO −→ 2Hg + O 2 (f )2 C 2 H 6 + 5O 2 −→ 4CO + 6H 2 O
(c) 2 C + O 2 −→ 2CO (g)C 2 H 4 + 3O 2 −→ 2CO 2 + 2H 2 O
(d )S + O 2 −→ SO 2

8.8. Write balanced chemical equations for the following reactions:
(a) Sodium plus fluorine yields sodium fluoride.
(b) Potassium chlorate, when heated, yields potassium chloride plus oxygen.
(c) Zinc plus copper(II) nitrate yields zinc nitrate plus copper.
(d) Magnesium hydrogen carbonate plus heat yields magnesium carbonate plus carbon dioxide plus
water.
(e) Magnesium hydrogen carbonate plus hydrobromic acid yields magnesium bromide plus carbon
dioxide plus water.
(f ) Lead(II) acetate plus sodium chromate yields lead(II) chromate plus sodium acetate.
Ans. (a)2 Na + F 2 −→ 2 NaF (Remember that free fluorine is F 2 .)
(b) 2 KClO 3 −→ 2 KCl + 3O 2 (Remember that free oxygen is O 2 .)
(c)Zn + Cu(NO 3 ) 2 −→ Zn(NO 3 ) 2 + Cu

(d )Mg(HCO 3 ) 2 −→ MgCO + H 2 O + CO 2
3
(e)Mg(HCO 3 ) 2 + 2 HBr −→ MgBr + 2H 2 O + 2CO 2
2
(f )Pb(C 2 H 3 O 2 ) 2 + Na 2 CrO 4 −→ PbCrO 4 + 2 NaC 2 H 3 O 2
8.9. Balance the following equation: Ba(ClO 4 ) 2 + Na 2 SO 4 −→ BaSO 4 + NaClO 4
Ans. Ba(ClO 4 ) 2 + Na 2 SO 4 −→ BaSO 4 + 2 NaClO 4
− 2−
The oxygen atoms need not be considered individually if the ClO 4 and SO 4 ions are considered as groups.
(See step 3, Sec. 8.2.)

8.10. Write balanced chemical equations for the following reactions:
(a) Phosphorus pentachloride plus water yields phosphoric acid plus hydrogen chloride.
(b) Sodium hydroxide plus sulfuric acid yields sodium hydrogen sulfate plus water.
(c) Ethane, C 2 H 6 , plus oxygen yields carbon dioxide plus water.
(d ) Octane, C 8 H 18 , plus oxygen yields carbon monoxide plus water.