Balance each of the following skeletal equations by using oxidation and reductio

Question

Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction.

a) Reaction of the selenite ion with chlorate ion:

SeO3(^2-) (s) + ClO3(^-) (aq) ? SeO4(^2-) (aq) + Cl2 (g)

b) Formation of propanone (acetone), which is used in nail polish remover, from isopropanol (rubbing alcohol) by the action of dichromate ion:

C3H7OH(aq) + Cr2O7(^2-) (aq) ? Cr(^3+) (aq) + C3H6O(aq)

c) Reaction of gold with selenic acid:

Au(s) + SeO4(^2-) (aq) ? Au(^3+) (aq) + SeO3(^2-) (aq)

d) Preparation of stibnine from antimonic acid:

H2SbO3(^2-) (s) + Zn(s) ? SbH3(aq) + Zn(^2+) (aq)

****all of these equations are copied down exactly as written in textbook

14.4 Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction (a) Reaction of the selenite ion with chlorate ion: Se032-(s) + CIO,-(aq)- SeO42. (aq) + Cl2(g) (b) Formation of propanone (acetone), which is used in nail polish remover, from isopropanol (rubbing alcohol) by the action of dichromate ion: C,H-OH(aq) + Cr,072. (aq) Cr3+(aq) + C,H60(aq) Au(s) + Seo/-(aq)- Au"(aq) + Seo?-(aq) H2SbO31-(s) + Zn(s) SbH,(aq) + Zn2+ (aq) c) Reaction of gold with selenic acid d) Preparation of stibnine from antimonic acid:

Explanation / Answer

a)

Half reactions are

ClO3-(aq) + 6 H+(aq) + 5 e-  ------> 1/2 Cl2(g) + 3 H2O

H2O + SeO32- ------> SeO42- + 2 H+ + 2 e-

Multiplying and adding

2ClO3-(aq) + 2H+(aq) +5SeO32- ----> Cl2(g) + H2O + 5SeO42-

SeO32- is the reducing agent

ClO3- is the oxidising agent

Cr2O72- + 14 H+(aq) + 6 e-  ------> 2 Cr3+(aq) + 7 H2O

C3H7OH ---->C3H6O + 2H+ + 2e-

Adding and multiplying

Cr2O72- + 8 H+(aq) + 3C3H7OH ---->3C3H6O +  2 Cr3+(aq) + 7 H2O

Cr2O72- is the oxidising agent

C3H7OH is the reducing agent

SeO42- + 2 H+ + 2 e- ------->H2O + SeO32-  

Au(s) -----> Au3+ + 3e-

Multiplying and adding

3SeO42- + 6 H+ + 2Au(s)------->3H2O + 3SeO32- +2Au3+

Au is the reducing agent

SeO42- is the oxidising agent

Zn(s) ----> Zn2+(aq) + 2e-

H2SbO32- + 7H+ + 5e- -----> SbH3(aq) + 3H2O

Multiplying and Adding

2 H2SbO32- + 5 Zn + 14 H+ ------> 2 SbH3 + 5 Zn2+ + 6 H2O

Zn is the reducing agent

H2SbO32- is the oxidising agent

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