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5.E: Chemical Reactions (Exercises)

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    The following questions are related to the material covered in this chapter. For additional discussion on each topic, also check the links included in each heading.

     

    Concept Review Exercises

     

    1. What are the parts of a chemical equation?
    2. Explain why chemical equations need to be balanced.

     

    Answers

     

    a. reactants and products

    b. Chemical equations need to be balanced to satisfy the law of conservation of matter.

     

     

     

     

    Exercises

     

    1. Write a chemical equation to express the fact that hydrogen gas and solid iodine react to make gaseous hydrogen iodide. Make sure the equation satisfies the law of conservation of matter.

    2. Write a chemical equation to express the fact that sodium metal and chlorine gas react to make solid sodium chloride. Make sure the equation satisfies the law of conservation of matter.

    3. Write an equation expressing the fact that hydrogen gas and fluorine gas react to make gaseous hydrogen fluoride. Make sure the equation satisfies the law of conservation of matter.

    4. Write an equation expressing the fact that solid potassium and fluorine gas react to make solid potassium fluoride. Make sure the equation satisfies the law of conservation of matter.

    5. Mercury reacts with oxygen to make mercury(II) oxide. Write a balanced chemical equation that summarizes this reaction.

    6. Octane (C8H18) reacts with oxygen to make carbon dioxide and water. Write a balanced chemical equation that summarizes this reaction.

    7. Propyl alcohol (C3H7OH) reacts with oxygen to make carbon dioxide and water. Write a balanced chemical equation that summarizes this reaction.

    8. Sulfuric acid (H2SO4) reacts with iron metal to make iron(III) sulfate and hydrogen gas. Write a balanced chemical equation that summarizes this reaction.

    9. Balance each equation.

      1. MgCl2 + K → KCl + Mg
      2. C6H12O6 + O2 → CO2 + H2O
      3. NaN3 → Na + N2 (This is the reaction used to inflate airbags in cars.)

    10. Balance each equation.

      1. NH4NO3 → N2O + H2O
      2. TiBr4 + H2O → TiO2 + HBr
      3. C3H5N3O9 → CO2 + N2 + O2 + H2O (This reaction represents the decomposition of nitroglycerine.)

    11. Balance each equation.

      1. NH3 + O2 → NO + H2O
      2. Li + N2 → Li3N
      3. AuCl → Au + AuCl3

    12. Balance each equation.

      1. NaOH + H3PO4 → Na3PO4 + H2O
      2. N2H4 + Cl2 → N2 + HCl
      3. Na2S + H2S → NaSH

    13. Chromium(III) oxide reacts with carbon tetrachloride to make chromium(III) chloride and phosgene (COCl2). Write the balanced chemical equation for this reaction.

    14. The reaction that occurs when an Alka-Seltzer tablet is dropped into a glass of water has sodium bicarbonate reacting with citric acid (H3C6H5O7) to make carbon dioxide, water, and sodium citrate (Na3C6H5O7). Write the balanced chemical equation for this reaction.

    15. When sodium hydrogen carbonate is used to extinguish a kitchen fire, it decomposes into sodium carbonate, carbon dioxide and water. Write a balanced chemical equation for this reaction.

    16. Elemental bromine gas can be generated by reacting sodium bromide with elemental chlorine. The other product is sodium chloride. Write a balanced chemical equation for this reaction.

     

    Answers

     

    1. H2(g) + I2(s) → 2HI(g)

    2.  

    1. H2(g) + F2(g) → 2HF(g)

    4.  

    1. 2Hg + O2 → 2HgO

    6.  

    1. 2C3H7OH + 9O2 → 6CO2 + 8H2O

    8.  

      1. MgCl2 + 2K → 2KCl + Mg
      2. C6H12O6 + 6O2 → 6CO2 + 6H2O
      3. 2NaN3 → 2Na + 3N2

    10.

    11.

    1. 4NH3 + 5O2 → 4NO + 6H2O
    2. 6Li + N2 → 2Li3N
    3. 3AuCl → 2Au + AuCl3

    12.

    13. Cr2O3 + 3CCl4 → 2CrCl3 + 3COCl2

    14.  

    15. 2NaHCO3 → Na2CO3 + CO2 + H2O

    16.  

     

    5.1-5.3: The Chemical Equation

    1. From the statement “nitrogen and hydrogen react to produce ammonia,” identify the reactants and the products.
    2. From the statement “sodium metal reacts with water to produce sodium hydroxide and hydrogen,” identify the reactants and the products.
    3. From the statement “magnesium hydroxide reacts with nitric acid to produce magnesium nitrate and water,” identify the reactants and the products.
    4. From the statement “propane reacts with oxygen to produce carbon dioxide and water,” identify the reactants and the products.
    5. Write and balance the chemical equation described by Exercise 1.
    6. Write and balance the chemical equation described by Exercise 2.
    7. Write and balance the chemical equation described by Exercise 3.
    8. Write and balance the chemical equation described by Exercise 4. The formula for propane is C3H8.
    9. Balance: ___NaClO3 → ___NaCl + ___O2
    10. Balance: ___N2 + ___H2 → ___N2H4
    11. Balance: ___Al + ___O2 → ___Al2O3
    12. Balance: ___C2H4 + ___O2 → ___CO2 + ___H2O
    13. How would you write the balanced chemical equation in Exercise 10 if all substances were gases?
    1. How would you write the balanced chemical equation in Exercise 12 if all the substances except water were gases and water itself were a liquid?

    Answers

    1. reactants: nitrogen and hydrogen; product: ammonia
    2.  

    3. reactants: magnesium hydroxide and nitric acid; products: magnesium nitrate and water

    4.  

    5. N2 + 3H2 → 2NH3

    6.  

    7. Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O

    8.  

    9. 2NaClO3 → 2NaCl + 3O2

    10.  

    11. 4Al + 3O2 → 2Al2O3

    12.  

    13. N2(g) + 3H2(g) → 2NH3(g)

    5.4: Composition, Decomposition, and Combustion Reactions

    1. Which is a composition reaction and which is not?
      1. NaCl + AgNO3 → AgCl + NaNO3
      2. CaO + CO2 → CaCO3
    2. Which is a composition reaction and which is not?
      1. H2 + Cl2 → 2HCl
      2. 2HBr + Cl2 → 2HCl + Br2
    3. Which is a composition reaction and which is not?
      1. 2SO2 + O2 → 2SO3
      2. 6C + 3H2 → C6H6
    4. Which is a composition reaction and which is not?
      1. 4Na + 2C + 3O2 → 2Na2CO3
      2. Na2CO3 → Na2O + CO2
    5. Which is a decomposition reaction and which is not?
      1. HCl + NaOH → NaCl + H2O
      2. CaCO3 → CaO + CO2
    6. Which is a decomposition reaction and which is not?
      1. 3O2 → 2O3
      2. 2KClO3 → 2KCl + 3O2
    7. Which is a decomposition reaction and which is not?
      1. Na2O + CO2 → Na2CO3
      2. H2SO3 → H2O + SO2
    8. Which is a decomposition reaction and which is not?
      1. 2C7H5N3O6 → 3N2 + 5H2O + 7CO + 7C
      2. C6H12O6 + 6O2 → 6CO2 + 6H2O
    9. Which is a combustion reaction and which is not?
      1. C6H12O6 + 6O2 → 6CO2 + 6H2O
      2. 2Fe2S3 + 9O2 → 2Fe2O3 + 6SO2
    10. Which is a combustion reaction and which is not?
      1. CH4 + 2F2 → CF4 + 2H2
      2. 2H2 + O2 → 2H2O
    11. Which is a combustion reaction and which is not?
      1. P4 + 5O2 → 2P2O5
      2. 2Al2S3 + 9O2 → 2Al2O3 + 6SO2
    12. Which is a combustion reaction and which is not?
      1. C2H4 + O2 → C2H4O2
      2. C2H4 + Cl2 → C2H4Cl2
    13. Is it possible for a composition reaction to also be a combustion reaction? Give an example to support your case.
    14. Is it possible for a decomposition reaction to also be a combustion reaction? Give an example to support your case.
    15. Complete and balance each combustion equation.
      1. C4H9OH + O2 → ?
      2. CH3NO2 + O2 → ?
    16. Complete and balance each combustion equation.
      1. B2H6 + O2 → ? (The oxide of boron formed is B2O3.)
      2. Al2S3 + O2 → ? (The oxide of sulfur formed is SO2.)
      3. Al2S3 + O2 → ? (The oxide of sulfur formed is SO3.)

    Answers

      1. not composition
      2. composition
    2.  
      1. composition
      2. composition
    4.  
      1. not decomposition
      2. decomposition
    6.  
      1. not decomposition
      2. decomposition
    8.  
      1. combustion
      2. combustion
    10.  
      1. combustion
      2. combustion
    12.  
    13. Yes; 2H2 + O2 → 2H2O (answers will vary)
    14.  
      1. C4H9OH + 6O2 → 4CO2 + 5H2O
      2. 4CH3NO2 + 3O2 → 4CO2 + 6H2O + 2N2

    5.5: Types of Chemical Reactions - Single and Double Displacement Reactions

    1. What are the general characteristics that help you recognize single-replacement reactions?
    2. What are the general characteristics that help you recognize double-replacement reactions?
    3. Assuming that each single-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Zn + Fe(NO3)2 → ?
      2. F2 + FeI3 → ?
    4. Assuming that each single-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Li + MgSO4 → ?
      2. NaBr + Cl2 → ?
    5. Assuming that each single-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Sn + H2SO4 → ?
      2. Al + NiBr2 → ?
    6. Assuming that each single-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Mg + HCl → ?
      2. HI + Br2 → ?
    7. Use the periodic table or the activity series to predict if each single-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. FeCl2 + Br2 → ?
      2. Fe(NO3)3 + Al → ?
    8. Use the periodic table or the activity series to predict if each single-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. Zn + Fe3(PO4)2 → ?
      2. Ag + HNO3 → ?
    9. Use the periodic table or the activity series to predict if each single-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. NaI + Cl2 → ?
      2. AgCl + Au → ?
    10. Use the periodic table or the activity series to predict if each single-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. Pt + H3PO4 → ?
      2. Li + H2O → ? (Hint: treat H2O as if it were composed of H+ and OH− ions.)
    11. Assuming that each double-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Zn(NO3)2 + NaOH → ?
      2. HCl + Na2S → ?
    12. Assuming that each double-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Ca(C2H3O2)2 + HNO3 → ?
      2. Na2CO3 + Sr(NO2)2 → ?
    13. Assuming that each double-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Pb(NO3)2 + KBr → ?
      2. K2O + MgCO3 → ?
    14. Assuming that each double-replacement reaction occurs, predict the products and write each balanced chemical equation.
      1. Sn(OH)2 + FeBr3 → ?
      2. CsNO3 + KCl → ?
    15. Use the solubility rules to predict if each double-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. Pb(NO3)2 + KBr → ?
      2. K2O + Na2CO3 → ?
    16. Use the solubility rules to predict if each double-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. Na2CO3 + Sr(NO2)2 → ?
      2. (NH4)2SO4 + Ba(NO3)2 → ?
    17. Use the solubility rules to predict if each double-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. K3PO4 + SrCl2 → ?
      2. NaOH + MgCl2 → ?
    18. Use the solubility rules to predict if each double-replacement reaction will occur and, if so, write a balanced chemical equation.
      1. KC2H3O2 + Li2CO3 → ?
      2. KOH + AgNO3 → ?

    Answers

    1. One element replaces another element in a compound.
    2.  
      1. Zn + Fe(NO3)2 → Zn(NO3)2 + Fe
      2. 3F2 + 2FeI3 → 3I2 + 2FeF3
    4.  
      1. Sn + H2SO4 → SnSO4 + H2
      2. 2Al + 3NiBr2 → 2AlBr3 + 3Ni
    6.  
      1. No reaction occurs.
      2. Fe(NO3)3 + Al → Al(NO3)3 + Fe
    8.  
      1. 2NaI + Cl2 → 2NaCl + I2
      2. No reaction occurs.
    10.  
      1. Zn(NO3)2 + 2NaOH → Zn(OH)2 + 2NaNO3
      2. 2HCl + Na2S → 2NaCl + H2S
    12.  
      1. Pb(NO3)2 + 2KBr → PbBr2 + 2KNO3
      2. K2O + MgCO3 → K2CO3 + MgO
    14.  
      1. Pb(NO3)2 + 2KBr → PbBr2(s) + 2KNO3
      2. No reaction occurs.
    16.  
      1. 2K3PO4 + 3SrCl2 → Sr3(PO4)2(s) + 6KCl
      2. 2NaOH + MgCl2 → 2NaCl + Mg(OH)2(s)

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