Question

In addition to mass balance, oxidation-reduction reactions must be balanced such that the number of electrons lost in the oxidation equals the number of electrons gained in the reduction. This balancing can be done by two methods: the half-reaction method or the oxidation number method. The half-reaction method balances the electrons lost in the oxidation half-reaction with the electrons gained in the reduction half-reaction. In either method H2O(l), OH−(aq), and H+(aq) may be added to complete the mass balance. Which substances are used depends on the reaction conditions.

Acidic solution In acidic solution, the nitrate ion can be used to react with a number of metal ions. One such reaction is NO3−(aq)+Sn2+(aq)→NO2(aq)+Sn4+(aq) Since this reaction takes place in acidic solution, H2O(l) and H+(aq) will be involved in the reaction. Places for these species are indicated by the blanks in the following restatement of the equation: NO3−(aq)+Sn2+(aq)+     −−−→NO2(aq)+Sn4+(aq)+     −−− Part A What are the coefficients of the reactants and products in the balanced equation above? Remember to include H2O(l) and H+(aq) in the appropriate blanks. Your answer should have six terms. Enter the equation coefficients in order separated by commas (e.g., 2,2,1,4,4,3). Include coefficients of 1, as required, for grading purposes. View Available Hint(s) Submit Basic solution Potassium permanganate, KMnO4, is a powerful oxidizing agent. The products of a given redox reaction with the permanganate ion depend on the reaction conditions used. In basic solution, the following equation represents the reaction of this ion with a solution containing sodium cyanide: MnO4−(aq)+CN−(aq)→MnO2(s)+CNO−(aq) Since this reaction takes place in basic solution, H2O(l) and OH−(aq) will be shown in the reaction. Places for these species are indicated by the blanks in the following restatement of the equation: MnO4−(aq)+CN−(aq)+     −−−→MnO2(s)+CNO−(aq)+     −−− Part B What are the coefficients of the reactants and products in the balanced equation above? Remember to include H2O(l) and OH−(aq) in the blanks where appropriate. Your answer should have six terms. Enter the equation coefficients in order separated by commas (e.g., 2,2,1,4,4,3). Include coefficients of 1, as required, for grading purposes.

Answer 1

Part A : The balanced chemical equation is : 2 NO₃^- (aq) + Sn²⁺ (aq) + 4 H⁺ (aq) 2 NO₂ (aq) + Sn⁴⁺ (aq) + 2 H₂O (l)

The equation coefficients are : 2, 1, 4, 2, 1, 2

Part B : The balanced chemical equation is : 2 MnO₄^- (aq) + 3 CN^- (aq) + H₂O (l) 2 MnO₂ (s) + 3 CNO^- (aq) + 2 OH^- (aq)

The equation coefficients are : 2, 3, 1, 2, 3, 2