6. Classify each of the following substances as a strong electrolyte or a nonelectrolyte: a. CH3OH b. BaCl2 c. KF d. H2SO4 e. KOH f.

Transcription

1 Chapter 4B Practice Problems 1. Balance the following equations: a. NaBH4(s) + H2O(l) NaBO2(aq) + H2(g) b. Mg(N3)2(s) + H2O(l) Mg(OH)2(aq) + HN3(aq) c. NaCl(aq) + SO3(g) + H2O(l) Na2SO4(aq) + HCl(aq) d. Fe2P(s) + S(s) P4S10(s) + FeS(s) e. KClO3(s) + C6H12O61(s) KCl(s) + CO2(g) + H2O(g) f. P2S5(s) + PCl5(s) PSCl3(g) g. LiBH4 + BF3 B2H6 + LiBF4 h. Ca3(PO4)2(s) + SiO2(s) + C(s) CaSiO3(l) + CO(g) + P4(g) 2. Write a balanced chemical equation for each of the following reactions. a. Calcium metal reacts with water to produce hydrogen gas and aqueous calcium hydroxide. b. The reaction of solid sodium oxide, Na2O, and water produces aqueous sodium hydroxide. c. Hot solid magnesium metal reacts in a nitrogen atmosphere to produce solid magnesium nitride, Mg3N2. d. The reaction of ammonia gas with oxygen gas at high temperatures in the presence of a copper metal catalyst produces the gases water and nitrogen dioxide. 3. A shortcut you can use to balance reactions in which polyatomic ions remain intact is to treat the ions as if they were elements. Use that shortcut to balance the following reactions: a. Pb(NO3)2(aq) + Na3PO4(aq) Pb3(PO4)2(s) + NaNO3(aq) b. Ag2CO3(s) + NaBr(aq) AgBr(s) + Na2CO3(aq) 4. Aspartame, C14H18N2O5, is a solid used as an artificial sweetener. Write the balanced equation for its combustion to carbon dioxide gas, liquid water, and nitrogen gas. 5. Phosphorus and oxygen react to form two different phosphorus oxides. The mass percentage of phosphorus in one of these oxides is 43.64%; in the other, it is 56.34%. a. Write the empirical formula of each phosphorus oxide. b. The molar mass of the former oxide is g mol 1 and that of the latter is g mol 1. Determine the molecular formula and name of each oxide. c. Write a balanced chemical equation for the formation of each oxide. 6. Classify each of the following substances as a strong electrolyte or a nonelectrolyte: a. CH3OH b. BaCl2 c. KF d. H2SO4 e. KOH f. CH3CH2CH2COOH 7. Write the balanced overall, complete ionic, and net ionic equations corresponding to each of the following reactions: a. BaBr2(aq) + Li3PO4(aq) Ba3(PO4)2(s) + LiBr(aq) b. NH4Cl(aq) + Hg2(NO3)2(aq) NH4NO3(aq) + Hg2Cl2(s) c. Co(NO3)3(aq) + Ca(OH)2(aq) Co(OH)3(s) + Ca(NO3)2(aq) d. BaCl2(aq) + K3PO4(aq) Ba3(PO4)2(s) + Kcl(aq) e. KCl(aq) + Hg2(NO3)2(aq) Hg2Cl2(s) + KNO3(aq)

2 f. K2C2O4(aq) + Fe(CH3CO2)3(aq) Fe2(C2O4)3(s) + KCH3CO2(aq) 8. Use the solubility rules to classify each of the following ionic compounds as soluble or insoluble in water: a. potassium phosphate, K3PO4 b. lead(ii) chloride, PbCl2 c. cadmium sulfide, CdS d. barium sulfate, BaSO4 e. cadmium nitrate, Cd(NO3)2 f. copper(ii) acetate, Cu(CH3CO2)2 g. cobalt(iii) hydroxide, Co(OH)3 h. silver bromide, AgBr 9. Each of the following procedures results in the formation of a precipitate. For each reaction, write the chemical equations describing the formation of the precipitate: the overall equation, the complete ionic equation, and the net ionic equation. Identify the spectator ions. a. (NH4)2CrO4(aq) is mixed with BaCl2(aq) b. CuSO4(aq) is mixed with Na2S(aq) c. FeCl2(aq) is mixed with (NH4)3PO4(aq) d. Potassium oxalate, K2C2O4(aq), is mixed with Ca(NO3)2(aq) e. NiSO4(aq) is mixed with Ba(NO3)2(aq) 10. Suppose that 2.50 g of solid (NH4)3PO4 is added to 50.0 ml of M CaCl2(aq). a. Write the chemical equation for the precipitation reaction and the net ionic equation. b. What is the concentration of each spectator ion (in moles per liter) after reaction is complete? Assume a final volume of 70.0 ml. 11. Predict the products and balance the following acid-base reactions: a. NaOH(aq) + HCl(aq) b. Strontium hydroxide + hydrofluoric acid c. Fe(OH)3(aq) + H2SO4(aq) d. Sulfurous acid + lithium hydroxide e. H3PO4(aq) + KCH3COO(aq) 12. Write balanced net ionic equations for the following reactions in basic solutions: a. MnO4 - (aq) + IO3 - (aq) MnO2(s) + IO4 - (aq) b. Cu(OH)2(s) + N2H4(aq) Cu(s) + N2(g) c. Fe(OH)2(s) + CrO4 2- (aq) Fe(OH)3(s) + Cr(OH)4 - (aq) 13. Write balanced net ionic equations for the following reactions in acidic solution: a. Zn(s) + VO 2+ (aq) Zn 2+ (aq) + V 3+ (aq) b. Ag(s) + NO3 - (aq) Ag + (aq) + NO2(g) c. Mg(s) + VO4 3- (aq) Mg 2+ (aq) + V 2+ (aq)

3 Solutions 1. Balance the following equations: a. NaBH4(s) + 2H2O(l) NaBO2(aq) + 4H2(g) b. Mg(N3)2(s) + 2H2O(l) Mg(OH)2(aq) + 2HN3(aq) c. 2NaCl(aq) + SO3(g) + H2O(l) Na2SO4(aq) + 2HCl(aq) d. 4Fe2P(s) + 18S(s) P4S10(s) + 8FeS(s) e. 4KClO3(s) + C6H12O6(s) 4KCl(s) + 6CO2(g) + 6H2O(g) f. P2S5(s) + 3PCl5(s) 5PSCl3(g) g. 3LiBH4 + 4BF3 2B2H6 + 3LiBF4 h. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) 6CaSiO3(l) + 10CO(g) + P4(g) 2. Write a balanced chemical equation for each of the following reactions. a. Ca(s) + H2O(l) H2(g) + Ca(OH)2(aq) b. Na2O(s) + H2O(l) NaOH(aq) c. Mg(s) + N2(g) Mg3N2(s) d. NH3(g) + O2(g) H2O(g) + NO2(g) 3. A shortcut you can use to balance reactions in which polyatomic ions remain intact is to treat the ions as if they were elements. Use that shortcut to balance the following reactions: a. 3Pb(NO3)2(aq) + 2Na3PO4(aq) Pb3(PO4)2(s) + 6NaNO3(aq) b. Ag2CO3(s) + 2NaBr(aq) 2AgBr(s) + Na2CO3(aq) 4. C14H18N2O5(s) + 16O2(g) 14CO2(g) + 9H2O(g) + N2(g) 5. Phosphorus and oxygen react to form two different phosphorus oxides. The mass percentage of phosphorus in one of these oxides is 43.64%; in the other, it is 56.34%. a. P2O5 and P2O3 b. P4O10 and P4O6 c. P4(s) + 5 O2(g) P4O10(s) and P4(s) + 3 O2(g) P4O6(s) 6. Classify each of the following substances as a strong electrolyte or a nonelectrolyte: a. CH3OH - nonelectrolyte b. BaCl2 strong c. KF - strong d. H2SO4 - strong e. KOH - strong f. CH3CH2CH2COOH weak (the COOH is a weak acid) 7. Write the balanced overall, complete ionic, and net ionic equations corresponding to each of the following reactions: a. 3BaBr2(aq) + 2Li3PO4(aq) Ba3(PO4)2(s) + 6LiBr(aq) 3Ba 2+ (aq) + 6Br - (aq) + 6Li + (aq) + 2PO4 3- (aq) Ba3(PO4)2(s) + 6Li + (aq) + 6Br - (aq) 3Ba 2+ (aq) + 2PO4 3- (aq) Ba3(PO4)2(s) b. 2NH4Cl(aq) + Hg2(NO3)2(aq) 2NH4NO3(aq) + Hg2Cl2(s) 2NH4 + (aq) + 2Cl - (aq) + Hg2 2+ (aq) + 2NO3 - (aq) 2NH4 + (aq) + 2NO3 - (aq) + Hg2Cl2(s) Hg2 2+ (aq) + 2Cl - (aq) Hg2Cl2(s) c. 2Co(NO3)3(aq) + 3Ca(OH)2(aq) 2Co(OH)3(s) + 3Ca(NO3)2(aq) 2Co 3+ (aq) + 6NO3 - (aq) + 3Ca 2+ (aq) + 6OH - (aq) 2Co(OH)3(s) + 3Ca 2+ (aq) + 6NO3 - (aq)

4 2Co 2+ (aq) + 6OH - (aq) 2C0(OH)3(s) d. 3BaCl2(aq) + 2K3PO4(aq) Ba3(PO4)2(s) + 6KCl(aq) 3Ba 2+ (aq) + 6Cl - (aq) + 6K + (aq) + 2PO4 3- (aq) Ba3(PO4)2(s) + 6K + (aq) + 6Cl - (aq) 3Ba 2+ (aq) + 2PO4 3- (aq) Ba3(PO4)2(s) e. 2KCl(aq) + Hg2(NO3)2(aq) Hg2Cl2(s) + 2KNO3(aq) 2K + (aq) +2Cl - (aq) + Hg2 2+ (aq) + 2NO3 - (aq) Hg2Cl2(s) + 2K + (aq) + 2NO3 - (aq) Hg2 2+ (aq) + 2Cl - (aq) Hg2Cl2(s) f. 3K2C2O4(aq) + 2Fe(CH3CO2)3(aq) Fe2(C2O4)3(s) + 6KCH3CO2(aq) 6K + (aq) + 3C2O4 2- (aq) +2Fe 3+ (aq) + 6CH3COO - (aq) Fe2(C2O4)3(s) + 6K + (aq) + 6CH3COO - (aq) 2Fe 3+ (aq) + 3C2O4 2- (aq) Fe2(C2O4)3(s) 8. Use the solubility rules to classify each of the following ionic compounds as soluble or insoluble in water: a. potassium phosphate, K3PO4 soluble b. lead(ii) chloride, PbCl2 insoluble c. cadmium sulfide, CdS insoluble d. barium sulfate, BaSO4 insoluble e. cadmium nitrate, Cd(NO3)2 soluble f. copper(ii) acetate, Cu(CH3CO2)2 soluble g. cobalt(iii) hydroxide, Co(OH)3 insoluble h. silver bromide, AgBr insoluble 9. Each of the following procedures results in the formation of a precipitate. For each reaction, write the chemical equations describing the formation of the precipitate: the overall equation, the complete ionic equation, and the net ionic equation. Identify the spectator ions. a. (NH4)2CrO4(aq) is mixed with BaCl2(aq) (NH4)2CrO4(aq) + BaCl2(aq) 2NH4Cl(aq) + BaCrO4(s) 2NH4 + (aq) + CrO4-2 (aq) + Ba 2+ (aq) + 2Cl - (aq) 2NH4 + (aq) + 2Cl - (aq) + BaCrO4(s) Ba 2+ (aq) + CrO4 2- (aq) BaCrO4(s) Spectator ions: NH4 + (aq) and Cl - (aq) b. CuSO4(aq) is mixed with Na2S(aq) CuSO4(aq) + Na2S(aq) CuS(aq) + Na2SO4(aq) Cu 2+ (aq) + SO4 2- (aq) + 2Na + (aq) + S 2- (aq) CuS(s) + 2Na + (aq) + SO4 2- (aq) Cu 2+ (aq) + S 2- (aq) CuS(s) Spectator ions: Na + (aq) and SO4 2- (aq) c. FeCl2(aq) is mixed with (NH4)3PO4(aq) 3FeCl2(aq) + 2(NH4)3PO4(aq) Fe3(PO4)2(s) + 6NH4Cl(aq) 3Fe 3+ (aq) + 6Cl - (aq) + 6NH4 + (aq) + 2PO4 3- (aq) Fe3(PO4)2(s) + 6NH4 + (aq) + 6Cl - (aq) 3Fe 3+ (aq) + 2PO4 3- (aq) Fe3(PO4)2(s) Spectator ions: NH4 + (aq) and Cl - (aq) d. Potassium oxalate, K2C2O4(aq), is mixed with Ca(NO3)2(aq) K2C2O4(aq) + Ca(NO3)2(aq) 2KNO3(aq) + CaC2O4(s) 2K + (aq) + C2O4 2- (aq) + Ca 2+ (aq) + 2NO3 - (aq) 2K + (aq) + 2NO3 - (aq) + CaC2O4(s)

5 Ca 2+ (aq) + C2O4 2- (aq) CaC2O4(s) Spectator ions K + (aq) and NO3 - (aq) e. NiSO4(aq) is mixed with Ba(NO3)2(aq) NiSO4(aq) + Ba(NO3)2(aq) Ni(NO3)2(aq) + BaSO4(s) Ni 2+ (aq) + SO4 2- (aq) + Ba 2+ (aq) + 2NO3 - (aq) Ni 2+ (aq) + 2NO3 - (aq) + BaSO4(s) Ba 2+ (aq) + SO4 2- (aq) BaSO4(s) Spectator ions: Ni 2+ (aq) and NO3 - (aq) 10. Suppose that 2.50 g of solid (NH4)3PO4 is added to 50.0 ml of M CaCl2(aq). a. 2(NH4)3PO4(aq) + 3CaCl2(aq) 6NH4Cl(aq) + Ca3(PO4)2(s) 3Ca 2+ (aq) + 2PO4 3- (aq) Ca3(PO4)2(s) b M Cl - (aq) and M NH4 + (aq) 11. Predict the products and balance the following acid-base reactions: a. NaOH(aq) + HCl(aq) H2O(l) + NaCl(aq) b. Sr(OH)2(aq) + 2HF(aq) SrF2(aq) + 2H2O(l) c. 2Fe(OH)3(aq) + 3H2SO4(aq) Fe2(SO4)3(aq) + 3H2O(l) d. H2SO4(aq) + 2LiOH(aq) Li2SO4(aq) + 2H2O(l) e. H3PO4(aq) + 3KCH3COO(aq) K3PO4(aq) + 3CH3COOH(aq) 12. Write balanced net ionic equations for the following reactions in basic solutions: a. 2MnO4 - (aq) + 3IO3 - (aq) + H2O(l) 2MnO2(s) + 3IO4 - (aq) + 2OH - (aq) b. 2Cu(OH)2(s) + N2H4(aq) 2Cu(s) + N2(g) + 4H2O(l) c. 3Fe(OH)2(s) + CrO4 2- (aq) + 4H2O(l) 3Fe(OH)3(s) + Cr(OH)4 - (aq) + OH - (aq) 13. Write balanced net ionic equations for the following reactions in acidic solution: a. Zn(s) + 2VO 2+ (aq) + 4H + (aq) Zn 2+ (aq) + 2V 3+ (aq) + 2H2O(l) b. Ag(s) + NO3 - (aq) + 2H + (aq) Ag + (aq) + NO2(g) + H2O(l) c. 3Mg(s) + 2VO4 3- (aq) + 16H + (aq) 3Mg 2+ (aq) + 2V 2+ (aq) + 8H2O(l)