21 End-of-Chapter Material
Additional Exercises
- Chemical equations can also be used to represent physical processes. Write a chemical reaction for the boiling of water, including the proper phase labels.
- Chemical equations can also be used to represent physical processes. Write a chemical reaction for the freezing of water, including the proper phase labels.
- Explain why 4Na(s) + 2Cl2(g) → 4NaCl(s) should not be considered a proper chemical equation.
- Explain why H2(g) + ½O2(g) → H2O(ℓ) should not be considered a proper chemical equation.
- Does the chemical reaction represented by 3Zn(s) + 2Al(NO3)3(aq) → 3Zn(NO3)2(aq) + 2Al(s) proceed as written? Why or why not?
- Does the chemical reaction represented by 2Au(s) + 2HNO3(aq) → 2AuNO3(aq) + H2(g) proceed as written? Gold is a relatively useful metal for certain applications, such as jewellery and electronics. Does your answer suggest why this is so?
- Explain what is wrong with the double-replacement reaction
NaCl(aq) + KBr(aq) → NaK(aq) + ClBr(aq). - Predict the products of and balance the double-replacement reaction Ag2SO4(aq) + SrCl2(aq) → ?
- Write the complete and net ionic equations for the double-replacement reaction
BaCl2(aq) + Ag2SO4(aq) → ? - Write the complete and net ionic equations for the double-replacement reaction
Ag2SO4(aq) + SrCl2(aq) → ? - Identify the spectator ions in the reaction NaCl(aq) + KBr(aq) → NaBr(aq) + KCl(aq). What is the net ionic equation?
- Complete the reaction 3H2SO4(aq) + 2Al(OH)3(s) → ? and identify the spectator ions. What is the net ionic equation?
- Can a reaction be a composition reaction and a redox reaction at the same time? Give an example to support your answer.
- Can a reaction be a combustion reaction and a redox reaction at the same time? Give an example to support your answer.
- Can a reaction be a decomposition reaction and a redox reaction at the same time? Give an example to support your answer.
- Can a reaction be a combustion reaction and a double-replacement reaction at the same time? Give an example to support your answer.
- Why is CH4 not normally considered an acid?
- Methyl alcohol has the formula CH3OH. Why would methyl alcohol not normally be considered a base?
- What are the oxidation numbers of the nitrogen atoms in these substances?
- N2
- NH3
- NO
- N2O
- NO2
- N2O4
- N2O5
- NaNO3
- What are the oxidation numbers of the sulfur atoms in these substances?
- SF6
- Na2SO4
- K2SO3
- SO3
- SO2
- S8
- Na2S
- Disproportion is a type of redox reaction in which the same substance is both oxidized and reduced. Identify the element that is disproportionating in 2CuCl(aq) → CuCl2(aq) + Cu(s) and indicate the initial and final oxidation numbers of that element.
- Disproportion is a type of redox reaction in which the same substance is both oxidized and reduced. Identify the element that is disproportionating in
3Cl2(g) + 6OH−(aq) → 5Cl−(aq) + ClO3−(aq) + 3H2O(ℓ) and indicate the initial and final oxidation numbers of that element.
Answers
- H2O(ℓ) → H2O(g)
- The coefficients are not in their lowest whole-number ratio.
- No; zinc is lower in the activity series than aluminum.
- In the products, the cation is pairing with the cation, and the anion is pairing with the anion.
- Complete ionic equation: Ba2+(aq) + 2Cl−(aq) + 2Ag+(aq) + SO42−(aq) → BaSO4(s) + 2AgCl(s)
Net ionic equation: The net ionic equation is the same as the complete ionic equation.
- Each ion is a spectator ion; there is no overall net ionic equation.
- Yes; H2 + Cl2 → 2HCl (answers will vary)
- Yes; 2HCl → H2 + Cl2 (answers will vary)
- It does not increase the H+ ion concentration; it is not a compound of H+.
-
- 0
- −3
- +2
- +1
- +4
- +4
- +5
- +5
- Copper is disproportionating. Initially, its oxidation number is +1; in the products, its oxidation numbers are +2 and 0, respectively.