Answer to Question #286130 in Chemistry for eli

Question

BALANCE THE FOLLOWING REDOX REACTION.. Show your full solution/method. Label each step. Briefly explain what you did in each step (few phrases and direct to the point, example: Balanced the oxygen atoms by adding water.).

a. Fe2O3 + CO ⇌ Fe + CO2 (in acidic medium)

b. Mg + NiO2 ⇌ Mg(OH)2 + Ni(OH)2 (in basic medium)

Answer 1

Question:

BALANCE THE FOLLOWING REDOX REACTION.. Show your full solution/method. Label each step. Briefly explain what you did in each step (few phrases and direct to the point, example: Balanced the oxygen atoms by adding water.).

a. Fe2O3 + CO ⇌ Fe + CO2 (in acidic medium)

b. Mg + NiO2 ⇌ Mg(OH)2 + Ni(OH)2 (in basic medium)

Solution:

a. Fe₂O₃ + CO ⇌ Fe + CO₂ (in acidic medium)

In acidic medium, we remove oxygen atoms by adding H⁺ and add oxygen atoms by adding water .

Half reactions:

Fe₂O₃ + 6H⁺ + 6e^- $\rightarrow$ 2Fe + 3H₂O

CO + H₂O - 2e^- $\rightarrow$ 2H⁺ + CO₂

In order to get the electron balance correct, multiply the second half reaction by 3:

Fe₂O₃ + 6H⁺ + 6e^- +3CO + 3H₂O - 6e^- $\rightarrow$ 2Fe + 3H₂O+6H⁺ + 3CO₂

Simplified:

Fe₂O₃ +3CO $\rightarrow$ 2Fe + 3CO₂

b. Mg + NiO₂ ⇌ Mg(OH)₂ + Ni(OH)₂ (in basic medium)

In basic medium, we add hydrogen atoms by adding water .

Half reactions:

Mg + 2OH^- -2e- $\rightarrow$ Mg(OH)₂

NiO₂ + 2H₂O + 2e^- $\rightarrow$ Ni(OH)₂ + 2OH^-

The number of the electrons coincide, so simply add the half reactions:

Mg + 2OH^- -2e^- + NiO₂ + 2H₂O + 2e^- $\rightarrow$ Mg(OH)₂ +Ni(OH)₂ + 2OH^-

Simplified:

Mg + NiO₂ + 2H₂O $\rightarrow$ Mg(OH)₂ +Ni(OH)₂

Answer: a. Fe₂O₃ +3CO $\rightarrow$ 2Fe + 3CO₂, b. Mg + NiO₂ + 2H₂O $\rightarrow$ Mg(OH)₂ +Ni(OH)₂