omework m 8 Which of these redox reactions do you expect to occur spontaneously
ID: 228905 • Letter: O
Question
omework m 8 Which of these redox reactions do you expect to occur spontaneously in the forward direction? Standard Electrode Potentials at 25 ° C Reduction Half-Reaction Ni2+ (aq) + 2 e- Ni(s) Zn2+ (aq) + 2e-Zn(s) Cd2+ (aq) + 2 e- Cd(s) Co2+ (aq) + 2 e- Co(8) PbH (aq) + 2 e-Pb(s) Fe2+ (aq) + 2 e- Fe(s) AP+ (aq) + 3 e-Al(s) Ag+ (aq) + e-Ag(s) Cr3+ (aq) + 3 e- Cr(s) Mn2+ (aq) +2 e-Mn(8) Eo (V) -023 -0.76 -0.40 -0.28 -0.13 -045 -1.66 0.80 -0.73 -1.18 Check all that apply Fe2+ (aq) + Zn(s)Fe(s) +m2+ (aq) Pb(s) + Mn2+ (aq) Pb2+ (aq) + Mn(a) Ni(s) + Zn2+ (aq) Ni2+ (aq) + Zn(s) Cr(s) + 3 Ag+ (aq) Cr3+ (aq) + 3 Ag(s) Back-Explanation / Answer
If Eo cell = + ve , then reaction is spontaneous
1) Given reaction, Fe2+ + Zn -----------> Fe + Zn2+
From given data, Fe2+ + 2e- -----------> Fe Eo = - 0.45 V
Zn ------------> Zn2+ + 2e- Eo = + 0.76
-------------------------------------------------------------------
Then, add above two reactions
Fe2+ + Zn -----------> Fe + Zn2+ Eo cell = -0.45 V+ 0.76 V = + 0.31 V
Hence, Eo = +ve
Therefore, the reaction is Spontaneous.
2)
Given reaction, Pb + Mn2+ -----------> Pb2+ + Mn
From given data, Pb -----------> Pb2+ + 2e- Eo = + 0.13 V
Mn2+ + 2e- -----------> Mn Eo = - 1.18 V
-------------------------------------------------------------------
Then, add above two reactions
Pb + Mn2+ -----------> Pb2+ + Mn Eo cell = + 0.13 V - 1.18 V = - 1.05 V
Hence, Eo = - ve
Therefore, the reaction is NOT spontaneous.
3)
Given reaction, Ni + Zn2+ -----------> Ni2+ + Zn
From given data, Ni -----------> Ni2+ + 2e- Eo = + 0.23 V
Zn2+ + 2e- -----------> Zn Eo = - 0.76 V
-------------------------------------------------------------------
Then, add above two reactions
Ni + Zn2+ -----------> Ni2+ + Zn Eo cell = + 0.23 V - 0.76 V = - 0.53 V
Hence, Eo = - ve
Therefore, the reaction is NOT spontaneous.
4)
Given reaction, Cr + 3Ag+ -----------> Cr3+ + 3 Ag
From given data, Cr -----------> Cr3+ + 3e- Eo = + 0.73 V
Ag+ + e- -----------> Ag Eo = + 0.80 V
3Ag+ + 3e- -----------> 3Ag Eo = + 0.80 V
-------------------------------------------------------------------
Then, add above two reactions
Cr + 3Ag+ -----------> Cr3+ + 3 Ag Eo cell = + 0.73 V + 0.80 V = + 1.53 V
Hence, Eo = + ve
Therefore, the reaction is Spontaneous.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.