Standard Reduction Potential Half-Reaction Ca2 (aq) 2eCa (s) Mn2+ (aq) + 2e ? Mn

Question

Standard Reduction Potential Half-Reaction Ca2 (aq) 2eCa (s) Mn2+ (aq) + 2e ? Mn (s) Co2 (ag) +2eCo () 2 H (a) 2e H2) Ag)Ag Cl2e) 2e Eo, Volts AG -2.87 5P) NFE -0.28 0.00 0.80 1.36 bu E is Posie Given the partial list of standard reduction potentials above, answer Questions 1-5. 1. Will calcium (Ca) spontaneously reduce silver ion (Ag') to silver (Ag)? Briefly explain your answer. If yes, what is Eo? The reducip potential Ca rs nesate Shownn 3o-2.)3.41 80 2. Will silver metal react spontaneously with HCl (ag) to produce H2 (? Briefly explain. 3. What is the cell potential for the Mn/Mn2'|(Co /Co cell, based on the standard potentials given above?

Explanation / Answer

Question -1 - the reduction potential of Calcium is negative showing that it will self get reduced .However the reduction potential of Ag+ is high i.e 0.80 so it will easily get reduced So Calcium can easily reduce Silver spontaneously.

Q-2-Silver is below hydrogen in the activity series, and therefore silver metal does not react with H+ to produce silver ions and hydrogen gas. Since there is no Ag+ formed, then there can be no precipitate of white AgCl.

Interestingly enough, there is some evidence that nanoparticles of silver will react with HCl to make AgCl and H2.

To give a direct evidence for the reaction which has been proved impossible for the bulk Ag."
Meaning that the reaction can't occur with "normal sized" silver, but does occur with really small particles of silver.

Don't put too much stock in some other answers. Hydrochloric acid is an aqueous solution, not a liquid, and hydrogen needs to be a product.

It would be wrong to assume that this reaction could occur at any scale :
2Ag (s) + 2HCl (aq) => 2AgCl (s) + H2 (g)

What we should write is this:
2Ag (s) + 2HCl (aq) => NO REACTION

The article that I alluded to earlier, is an EXCEPTION, and the methanism for this reaction is unsubstantiated. It is quite possible that it occurs because of some side reaction.

Regardless of the particle size, the electrochemical potentials still indicate that the reaction of silver metal with HCl(aq) is NON SPONTANEOUS.

Q-3-Here given that ,

Mn2+     + 2e-à Mn     Eo= -1.18

Co2+       +2e- àCo      Eo= -0.28

So here 2 cases can be considered as follows;

Case 1: reversing the Mn reduction:

Eºnet =  Eºox(Mn) + Eºred(Co)

        =(-1.18) + (-0.28)

        = -1.46 V

Case 2: reversing the Co reduction:

Eºnet =  Eºred(Co) + Eºox(Mn)

Eºnet = ( -0.28) + ( -1.18)

Eºnet = -1.46 V

Thus in both the cases cell potential is -1.46V.

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.