Worksheet: Balancing Ionic Half-Equations in Acidic or Basic Conditions

In this worksheet, we will practice balancing ionic half-equations in reduction–oxidation reactions by adding water, protons, hydroxide ions, and electrons.

Q1:

When liquid bromine reacts with sulfur dioxide gas under acidic aqueous conditions, bromide and sulfate ions are produced.

Write the oxidation half-equation for this reaction, including state symbols.

  • ASO()+HO()SO()+2H()+4e3242+glaqaq
  • BSO()+2HO()SO()+4H()+4e2242+glaqaq
  • CSO()+2HO()SO()+4H()+2e2242+glaqaq
  • DSO()+HO()SO()+2H()+2e3242+glaqaq
  • ESO()+2HO()SO()+4H()+6e2242+glaqaq

Write a balanced ionic equation for this reaction, including state symbols.

  • A2Br()+SO()+2HO()4Br()+SO()+4H()22242+lglaqaqaq
  • BBr()+SO()+HO()2Br()+SO()+2H()23242+lglaqaqaq
  • C3Br()+2SO()+4HO()6Br()+2SO()+8H()22242+lglaqaqaq
  • DBr()+SO()+2HO()2Br()+SO()+4H()22242+lglaqaqaq
  • E3Br()+2SO()+2HO()6Br()+2SO()+4H()23242+lglaqaqaq

Q2:

Manganate ions (MnO42) react under basic aqueous conditions to produce permanganate (MnO4) and solid manganese dioxide.

Write the reduction half-equation for this reaction, including state symbols.

  • AMnO()+4HO()+6eMnO()+4OH()4222aqlsaq
  • BMnO()+2HO()+4eMnO()+4OH()4222aqlsaq
  • CMnO()+2HO()+6eMnO()+4OH()4222aqlsaq
  • DMnO()+2HO()+2eMnO()+4OH()4222aqlsaq
  • EMnO()+4HO()+2eMnO()+8OH()4222aqlsaq

Write a balanced ionic equation for this reaction, including state symbols.

  • A2MnO()+2HO()MnO()+MnO()+4OH()42224aqlsaqaq
  • B5MnO()+2HO()MnO()+4MnO()+4OH()42224aqlsaqaq
  • C3MnO()+2HO()MnO()+2MnO()+4OH()42224aqlsaqaq
  • D3MnO()+4HO()2MnO()+MnO()+8OH()42224aqlsaqaq
  • E5MnO()+6HO()3MnO()+2MnO()+12OH()42224aqlsaqaq

Q3:

When permanganate (MnO4) ions react with nitrite ions under basic aqueous conditions, solid manganese(IV) dioxide and nitrate ions are produced.

Write the reduction half-equation for this reaction, including state symbols.

  • AMnO()+2HO()+3eMnO()+4OH()422aqlsaq
  • BMnO()+4HO()+5eMnO()+8OH()422aqlsaq
  • CMnO()+4HO()+4eMnO()+4OH()422aqlsaq
  • DMnO()+2HO()+4eMnO()+4OH()422aqlsaq
  • EMnO()+2HO()+3eMnO()+2OH()422aqlsaq

Write a balanced ionic equation for this reaction, including state symbols.

  • AMnO()+3NO()+2OH()MnO()+3NO()+HO()42232aqaqaqsaql
  • B2MnO()+3NO()+HO()2MnO()+3NO()+2OH()42223aqaqlsaqaq
  • C3MnO()+2NO()+4HO()3MnO()+2NO()+8OH()42223aqaqlsaqaq
  • DMnO()+2NO()MnO()+2NO()4223aqaqsaq
  • E2MnO()+5NO()+2OH()2MnO()+5NO()+HO()42232aqaqaqsaql

Q4:

When cyanide ions react with chlorine dioxide under acidic aqueous conditions, cyanate (CNO) and chloride ions are produced.

Write the reduction half-equation for this reaction, including state symbols.

  • AClO()+2HO()+6eCl()+4OH()22aqlaqaq
  • BClO()+4H()+4eCl()+2HO()2+2aqaqaql
  • CClO()+4H()+6eCl()+2HO()2+2aqaqaql
  • DClO()+4H()+5eCl()+2HO()2+2aqaqaql
  • EClO()+2HO()+4eCl()+4OH()22aqlaqaq

Write a balanced ionic equation for this reaction, including state symbols.

  • A3CN()+ClO()+HO()3CNO()+Cl()+2H()22+aqaqlaqaqaq
  • B5CN()+2ClO()+HO()5CNO()+2Cl()+2H()22+aqaqlaqaqaq
  • C5CN()+ClO()+3HO()5CNO()+Cl()+6H()22+aqaqlaqaqaq
  • DCN()+2ClO()+6H()CNO()+2Cl()+3HO()2+2aqaqaqaqaql
  • ECN()+ClO()+2H()CNO()+Cl()+HO()2+2aqaqaqaqaql

Q5:

When hydrogen sulfide gas reacts with Hg22+ ions in solution, liquid mercury and solid elemental sulfur are produced.

Write the oxidation half-equation for this reaction, including state symbols.

  • AHg()+2e2Hg()22+aql
  • BHS()S()+2H()+2e2+gsaq
  • CHS()S()+H()22gsg
  • DHS()S()+H()+2e22gsg
  • EHg()2Hg()+2e22+aql

Write a balanced ionic equation for this reaction, including state symbols.

  • AHg()+HS()Hg()+S()+H()22+222aqglsg
  • BHg()+HS()2Hg()+S()+2H()22+2+aqglsaq
  • CHg()+S()Hg()+S()22+22aqgls
  • DHg()+2HS()2Hg()+2S()+4H()22+2+aqglsaq
  • EHg()+S()2Hg()+S()22+2aqgls

Q6:

When tin(II) ions react with copper(II) ions in water, tin(IV) and copper(I) ions are produced.

Write the oxidation half-equation for this reaction, including state symbols.

  • ASn()Sn()+2e4+2+aqaq
  • BCu()Cu()+e+2+aqaq
  • CSn()Sn()+2e2+4+aqaq
  • DCu()+eCu()2++aqaq
  • ESn()Sn()+e+2+aqaq

Write a balanced ionic equation for this reaction, including state symbols.

  • ASn()+2Cu()Sn()+2Cu()+2+2++aqaqaqaq
  • BSn()+2Cu()Sn()+2Cu()2+2+4++aqaqaqaq
  • CSn()+2Cu()Sn()+2Cu()4++2+2+aqaqaqaq
  • DSn()+Cu()Sn()+Cu()2+2+4++aqaqaqaq
  • ESn()+Cu()Sn()+Cu()2++4+2+aqaqaqaq

Q7:

Write the oxidation half-equation, including state symbols, for the conversion of chloride to chlorate(V) ions under basic aqueous conditions.

  • ACl()+6OH()ClO()+3HO()+6e32aqaqaql
  • BCl()+6OH()ClO()+3HO()+4e32aqaqaql
  • CCl()+6OH()ClO()+3HO()+4e22aqaqaql
  • DCl()+2HO()ClO()+4H()+4e22+aqlaqaq
  • ECl()+3HO()ClO()+6H()+6e23+aqlaqaq

Q8:

Write the reduction half-equation, including state symbols, for the conversion of manganate(VII) to manganese(II) ions under acidic aqueous conditions.

  • AMnO()+8H()+5eMn()+4HO()4+2+2aqaqaql
  • BMnO()+4HO()+7eMn()+8OH()422+aqlaqaq
  • CMnO()+4HO()+3eMn()+8OH()4322+aqlaqaq
  • DMnO()+10H()+5eMn()+5HO()53+2+2aqaqaql
  • EMnO()+10HO()+5eMn()+20OH()5322+aqlaqaq

Q9:

Write the oxidation half-equation, including state symbols, for the conversion of sulfite to sulfate ions under acidic aqueous conditions.

  • ASO()+HO()SO()+2H()+2e324+aqlaqaq
  • BSO()+2OH()SO()+HO()+2e342aqaqaql
  • CSO()+HO()SO()+2H()+2e32242+aqlaqaq
  • DSO()+2OH()SO()+HO()+e3422aqaqaql
  • ESO()+2OH()SO()+HO()+e32422aqaqaql

Q10:

Write the reduction half-equation, including state symbols, for the conversion of aqueous iodate(V) ions to solid elemental iodine under basic conditions.

  • A2IO()+12H()+10eI()+6HO()3+22aqaqsl
  • B2IO()+4HO()+4eI()+8OH()2222aqlsaq
  • C2IO()+8H()+4eI()+4HO()22+22aqaqsl
  • D2IO()+4HO()+6eI()+8OH()222aqlsaq
  • E2IO()+6HO()+10eI()+12OH()322aqlsaq

Q11:

Write the oxidation half-equation, including state symbols, for the conversion of water to oxygen under acidic conditions.

  • A2HO()O()+2H()+4e222lgg
  • B2HO()O()+2H()+2e222lgg
  • C2HO()+4eO()+4H()22+lgaq
  • D2HO()O()+4H()+2e22+lgaq
  • E2HO()O()+4H()+4e22+lgaq

Q12:

Under acidic aqueous conditions, the permanganate ion dissociates and forms Mn2+ and 4 molecules of water. In this reaction, how many moles of electrons are transferred per mole of permanganate ions?

Q13:

Which of the following is a properly balanced half-reaction under acidic conditions?

  • A12H+5I+IO3I+6HO+322
  • B3Cd+8H+2NO3Cd+2NO+8HO+32+2
  • C2Au+6I2Au+3I3+2
  • D2Fe(OH)+HO2Fe(OH)2223
  • ECrO+8H+3HCO2Cr+7HO+6CO272+2243+22

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