# 7.E: Chapter 7 Homework

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Evidence of a Chemical Reaction

1. Which of the following observations indicates a chemical reaction?

a) burning fire wood

b) rusting iron

c)  ice cubes melting in a glass of water

2. Which of the following observations indicates a chemical reaction?

a) solid calcium forming at the bottom of a test tube after mixing two solutions

b) crushing a solid cube of NaCl into a fine powder

c) a car’s liquid windshield cleaner freezing

3. Which of the following observations does not indicate a chemical reaction?

a) gas bubbles forming when Alka-Seltzer tablets are in water

b) a cold pack becoming cold when activated by mixing the interior components

c) a thick layer of foam forming at the top of soda being poured into a glass

Writing and Balancing Chemical Equations

4. Consider the unbalanced chemical equation:

Pb(s)+Cl2(g) →PbCl(s)

A student tries to balance the equation by changing the subscript 2 on Cl to a 1. Explain why this is incorrect and what should be done to balance this equation.

5. Consider the unbalanced chemical equation:

H2(g)+O2(g) → H2O(l)

Which of the following choices is the correct way to write the balanced chemical equation?

a)     H2(g) + 2O2(g) →H2O(l)

b) 2H2(g) + O2(g) →2H2O(l)

c)  H2(g) + O2(g) →H2O2(l)

6. Consider the following incorrectly balanced chemical equation:

Fe3+(aq) + Cl-(aq) →2FeCl3(s)

What coefficients must be placed in front of each reactant in order for this to be correctly balanced?

7. Write a balanced chemical equation for each chemical reaction:

a) Solid zinc reacts with aqueous hydrochloric acid (HCl) to form zinc chloride and hydrogen gas.

b) Gaseous methane (CH4) reacts with oxygen gas to form carbon dioxide gas and liquid water.

c) Aqueous calcium hydroxide reacts with carbon dioxide to form calcium carbonate and liquid water.

d) Solid iron (III) oxide reacts with chlorine gas to form iron (III) chloride and oxygen gas.

8. Write a balanced chemical equation for each chemical reaction:

a) Aqueous potassium hydroxide is added to hydrofluoric acid to form water and potassium fluoride.

b) Aluminum metal is added to aqueous copper (II) sulfate so that copper metal and aluminum sulfate are formed.

c) Potassium metal is placed in water to form potassium hydroxide and hydrogen gas.

d) Iron metal is placed in an aqueous solution of copper (II) nitrate so that copper metal and iron (III) nitrate are formed.

9. Write a balanced chemical equation for each chemical reaction:

a) Aqueous dinitrogen trioxide reacts with water to form nitrous acid (HNO2).

b) Xenon gas reacts with fluorine gas to produce xenon hexafluoride.

c) Ammonium nitrate decomposes to produce gaseous dinitrogen monoxide and water.

d) Molecular iodine reacts with nitric acid to produce iodic acid (HIO3), nitrogen dioxide gas, and hydrogen gas.

10. Write a balanced chemical equation for the reaction of aluminum bromide and chlorine gas to form aluminum chloride and bromine gas.

11. Write a balanced chemical equation for the combustion (reaction with oxygen) of hexane (C6H24).

12. Write a balanced chemical equation for the combination of sulfur dioxide and oxygen to produce sulfur trioxide.

13. Write a balanced chemical equation for the decomposition of sugar (C6H12O6) into carbon and water.

14. Write a balanced chemical equation for the combination of barium chloride and potassium sulfate to form barium sulfate and potassium chloride.

15. Write a balanced chemical equation for the reaction of water vapor with sodium metal to produce sodium hydroxide and hydrogen gas.

16. Balance the following chemical equations:

a) C2H6(g) + O2(g) → CO2(g) + H2O(l)

b) BaCO3(s) + HNO3(aq) → Ba(NO3)2 (aq) + CO2(g) + H2O(l)

c) H3PO4(aq) + HCl(aq) → PCl5(aq) + H2O(l)

d) KNO3(aq) + C12H22O11 (aq) → N2(g) + CO2(g) + H2O(l) + K2CO3(aq)

17. Balance the following chemical equations:

a) C4H10(g) + O2(g) → CO2(g) + H2O(l)

b) MgS(s) + O2(g) → MgO(aq) + SO2(g)

c) P4S3(s) + KClO3(aq) → P2O5(aq) + KCl(aq) + SO2(g)

d) Fe3O4(aq) + CO(g) → CO2(g) + Fe(s)

18. Balance the following chemical equations:

a) Li2O(s) + H2O(l) → LiOH(aq)

b) Cu(s) + AgNO3(aq) → Ag(s) + Cu(NO3)2(aq)

c) H3PO4 (aq) + NaOH(aq) → Na3PO4(aq) + H2O(l)

d) Cl2(g) + NaBr(aq) → NaCl(aq) + Br2(l)

19. Determine if the following chemical reactions are balanced correctly; if not, correct them.

a) FeS(s) + 2HCl(aq) → FeCl2(aq) + H2S(g)

b) H2SO4(aq) + 2NaNO2(aq) → HNO2(aq) + Na2SO4(aq)

c) NaCl(aq) + 2F2(g) → NaF(aq) + 2Cl2(g)

d) HNO3(aq) + NaHCO3(aq) → NaNO3(aq) + H2O(l) + CO2(g)

20. Explain what is wrong with the following chemical reaction.

KCl(aq) + LiBr(aq) → LiK(aq) + ClBr(aq)

21. Write chemical reactions for the following physical processes. Do they require balancing?

a) Boiling of water.

b) Freezing of water.

c) Condensation of water.

Solubility

22. How does an ionic substance dissolve in water?

23. Can polyatomic ions dissociate when they are dissolved in water? Why or why not?

24. Which of the following cations would form a soluble compound with the anion: CO32-? (There may be more than one answer)

a) Ca2+

b) NH4+

c) Ba2+

d) K+

25. Which of the following cations would form a soluble compound with the anion:SO42 -? (There may be more than one answer)

a) Ca2+

b) Pb2+

c) Na+

d) Mg2+

26. Using only the anions Cl- and OH-, and the five cations provided, create as many insoluble molecules as possible and write the formulas below.

Ag+                                                                   OH-

Mg2+

Fe2+                                              Cl-

Zn2+

Pb2+

27. Which compound(s) labeled as soluble are actually insoluble?

CaCl2(aq)                                                  KOH(aq)                                                                 BaSO4(aq)

H2SO4(aq)                                                CaCO3(aq)                                                              NaCl(aq)

28. Which compound(s) labeled as insoluble are actually soluble?

SiO2(s)                                                       Na(C2H3O2) (s)                                                       CuS(s)

Pb(NO3) (s)                                              HF (s)                                                                      PbCl2(s)

29. Ions in a sodium chloride solution have the ability to conduct electricity. What type of solutions are these?

a) strong electrolyte

b) pure

c) weak electrolyte

d) electrical

30. Predict whether or not the missing product of the following reactions are soluble or insoluble.

a) CoCl2(aq) + Na2SO4(aq) → 2NaCl(aq) + __________

b) 2NaOH(aq) + MgCl2(aq) → 2NaCl(aq) + __________

c) 2AgNO3(aq) + Na2S(aq) → 2NaNO3(aq) + __________

d) NaCl(aq) + HI(aq) → HCl(aq) + __________

31. Write a molecular equation for the precipitation reaction that occurs when the following pairs of solutions are mixed.

a) calcium chromate and copper (II) nitrate

b) potassium bromide and mercury (I) sulfate

c) lithium nitrate and ammonium sulfide

d) lead (II) nitrate and sodium chloride

32. Determine whether the following compound mixtures form a precipitate. If they do, write the precipitation reaction. If they do not, write “No Reaction.”

a) lithium hydroxide and magnesium nitrate

b) hydrochloric acid and potassium sulfate

c) sodium iodide and ammonium sulfate

d) lead acetate and sodium chloride

33. Correct the following incorrectly written precipitation reactions by rewriting the correct equation and explaining what was incorrect with the original.

a) Na2SO4(aq) + BaCl2(aq) → Na2SO4(s) + BaCl2(aq)

b) KI(aq) + Pb(NO3)2(aq) → KNO3(aq) + PbI2(s)

c) 2AgNO3(aq) + Na2S(aq) → Ag2S(aq) + 2NaNO3(s)

34. Correct the following incorrectly written precipitation reactions by rewriting the correct equation and explaining what was incorrect with the original.

a) FeSO4(aq) + Ba(OH)2(aq) → Fe(OH)2(aq) + BaSO4(s)

b) 2(NH4)3PO4(aq) + 3Na2SO4(aq) → 3(NH4)2SO4(s) + 2Na3PO4(aq)

c) Ca(OH)2(s) + Na2SO4(aq) → CaSO4(s) + 2NaOH(aq)

35. There are two beakers, each containing a mix of two solutions. Beaker A contains potassium phosphate and calcium nitrate. Beaker B contains sodium hydroxide and barium bromide.  Provide the chemical equation.

Ionic and Net Ionic Equations

36. What is a molecular equation? A complete ionic equation? A net ionic equation? Provide an example of each.

37. What is a single displacement reaction? What is a double displacement reaction? Provide an example of each.

38. Write the balanced total ionic and net ionic equations for the following balanced reactions.

a) 2CoBr3(aq) + 3K2S(aq) → 6KBr(aq) + Co2S3(s)

b) 2Cr(NO3)3(aq) + 3FeSO4(aq) → 3Fe(NO3)2(aq) + Cr2(SO4)3(aq)

c) 2Fe(s) + 3Cu(NO3)2(aq) → 3Cu(s) + 2Fe(NO3)3(aq)

d) Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)

39. Write the balanced total ionic and net ionic equations for the following balanced reactions.

a) 2RbF(aq) + CuSO4(aq) → Rb2SO4(aq) + CuF2(aq)

b) SrBr2(aq) + K2SO4(aq) → SrSO4(s) + 2KBr(aq)

c) NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

d) 2Bi(OH)3(s) + 3H2SO4(aq) → Bi2SO4(s) + 6H2O(l)

40. Write the balanced molecular, total ionic, and net ionic equations for the following mixtures of solutions.

a) manganese(II) chloride and ammonium carbonate

b) potassium hydroxide and hydrofluoric acid

c) ammonium phosphate and zinc nitrate

d) acetic acid and sodium bicarbonate

Acid-Base Reactions

41. Acid-Base Reactions, also known as _________________ reactions, typically produce ___________ and an ionic compound which is a ___________.

42. Balance and predict the products of the following acid-base reactions.

a) HCl(aq) + NaOH(aq) →

b) H3PO4(aq) + Ca(OH)2(aq) →

c) H2SO4(aq) + KOH(aq) →

d) HNO3(aq) + Al(OH)3(s) →

43. Predict the products for the neutralization reaction of the following two mixtures. Remember to balance the equation.

a) chloric acid and zinc hydroxide

b) sulfuric acid and barium hydroxide

c) hydrobromic acid and lithium hydroxide

d) hydrofluoric acid and calcium hydroxide

Combustion Reactions

44. Combustion reactions occur when an organic compound reacts with ______________ to produce water and _________________.

45. Balance and predict the products of the following combustion reactions.

a) C6H6(l) + O2(g) →

b) C6H12O6(aq) + O2(g) →

c) C2H5OH(l) + O2(g) →

46. Balance and write the equation for the combustion of the following compounds.

a) methane

b) butane

c) butanol

Classifying Chemical Reactions

47. Classify each of the following formats of equations.

a) AB + CD → AD + CB

b) AB → A + B

c) A+ BC → AC + B

d) A + B → AB

48. Classify each of the following chemical reactions as: synthesis, decomposition, single-displacement, or double-displacement.

a) 2HCl(aq) + Mg(s) → H2(g) + MgCl2(aq)

b) N2(g) + 3H2(g) → 2NH3(g)

c) CO(g) + Cl2(g) → COCl2(g)

49. Classify each of the following chemical reactions as: synthesis, decomposition, single-displacement, or double-displacement.

a) SbCl5(g) → SbCl3(g) + Cl2(g)

b) 2HC2H3O2(aq) + Ca(OH)2(aq) → 2H2O(l) + Ca(C2H3O2)2(aq)

c) Cu2O(s) + C(s) → 2Cu(s) + CO(g)

50. Classify each of the following chemical reactions as: synthesis, decomposition, single-displacement, or double-displacement.

a) K2SO4(aq) + BaBr2(aq) → BaSO4(s) + 2KBr(aq)

b) 2Na(s) + Cl2(g) → 2NaCl(aq)

c) 2HClO4(aq) + CaCO3(s) → H2O(l) + CO2(g) + Ca(ClO4)2(aq)

51. Classify each of the following chemical reactions as: synthesis, decomposition, single-displacement, or double-displacement.

a) 2HgO(s) → 2Hg(l) + O2(g)

b) HI(aq) + K(s) → H2(g) + KI(aq)

c) TiO2(s) + 2C(s) → Ti(s) + 2CO(g)

52. Classify each of the following chemical reactions as: synthesis, decomposition, single-displacement, or double-displacement.

a) CaSO3(s) → CaO(s) + SO2(g)

b) 2KI(aq) + Pb(NO3)2(aq) → 2KNO3(aq) + PbI2(s)

c) Fe(s) + Cl2(g) → FeCl2(s)

Cumulative Challenge Problems

53. Predict the products for the following reactions. If no reaction occurs, write “No Reaction.” Write the balanced molecular, total ionic equations, and net ionic equations.

a) BaCl2(aq) + Na2SO4 (aq) →

b) Na2S(aq) + LiF(aq) →

c) H2SO4(aq) + Pb(NO3)2(aq) →

54. Predict the products of the following chemical reactions. If no reaction occurs, write “No Reaction.” Write the balanced net ionic equation. Write the sum of the coefficients of the balanced molecular equation and of the net ionic equation.

a) sodium sulfate and calcium iodide

b) ammonium chloride and silver acetate

c) sodium hydroxide is added to hydroiodic acid for the purpose of neutralization

55. Predict what kind of reaction occurs based on the substances provided. Write the balanced molecular equations for each reaction. Write “No Reaction” if no reaction occurs. Write the sum of the coefficients of the balanced reaction.

a) perchloric acid is poured onto solid calcium carbonate

b) iron metal is placed in copper (II) nitrate

c) gaseous oxygen is added to liquid nonane

56. Predict the products of the following reactions. Classify them in as many ways as possible.

a) KOH(aq) + AlCl3(aq) →

b) Li2O(aq) + H2O(l) →

c) 2Na(s) + 2H2O(l) →

d) KClO3(aq) →

57. Write the balanced combustion reactions for the following organic compounds.

a) (CH3)2CHOH(l)

b) C10H8(s)

c) CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3(l)

d) C12H22O11(aq)

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