Question

Balance the following oxidation-reduction equation. The reactions occur in acidic or basic aqueous solution, as indicated. a. Co2+ + H2S +Co+Ss (acidic) O Co2+ +8H2S + 2Co + S8 + 16H+ O8Co2+ + 8H,8 + 8Co+Sg + 16+ Co2+ + 8H2S + 2Co + S8 b. S + Bry + SO 2 + Br” (basic) OS? + 4Br2 + 80H 8Br + SO4 + 4H2O O $2 + 4Br2 + 4H20 +8Br” + SO4 + 8H+ Os + 4Br2 + 4H,0 8Brº +50 c. TI + NO, TI(OH)4 + NH, (basic) O8T1+3NO:" + 23H,0 +8TI(OH)4- + 3NH, +5H O 8T1+3NO," +501 + 18H, 08TI(OH)4 + 3NH, OTI +3NO; + 50H" + Tl(OH)+ 3NH, d. TCO + C202 + TcO2 + CO2 (basic) O2T004” +3C,042 + 2TcO2 + 6CO2 O2Tc04" +3C,04% + 4H,0 2TcO2 +6C0, +801 O2T004- +3C,042 +8H+ + 2TcO2 +6CO2 + 4H2O

Answer 1

a. Co^2+ + H2S ----> Co + S8

The balanced equation in the acidic medium is:

8Co^2+ + 8H2S -----> 8Co + S8 + 16H^+

Option-2 is the correct answer.

b. S^2- + Br2 ------> SO4^2- + Br^-

The balanced equation in the basic medium is:

S^2- + 4Br2 + 8OH^- -----> 8Br^- + SO4^2- + 4H2O

Option-1 is the correct answer.

c. Tl + NO3^- --------> Tl(OH)4^- + NH3

The balanced equation in the basic medium is:

8Tl + 3NO3^- + 5 OH^- + 18H2O -----> 8 Tl(OH)4^- + 3 NH3

Option-2 is the correct answer.

d. TcO4^- + C2O4^2- -----> TcO2 + CO2

The balanced equation in the basic medium is:

2TcO4^- + 3C2O4^2- + 4H2O -----> 2TcO2 + 6CO2 + 8 OH^-

Option-2 is the correct answer.