Consider the following spontaneous reactions that occur in the forward direction

Question

Consider the following spontaneous reactions that occur in the forward directions at 25C standard conditions:

2 Ag(s) + Pd2+(aq) ---> 2 Ag+(aq) + pd(s)

Ga(s) + 3Ag+(aq) ---> Ga3+(aq) + 3Ag(s)

Sc(s) + Ga3+(aq) ---> Sc3+(aq) + Ga(s)

From the above information, predict whether the following reactions will be spontaneous in the forward direction at 25C under standard conditions.

A)3Pd(s) + 2Ga3+(aq)---> 3Pd2+(qq) + 2Ga(s)

B)2Sc(s) + 2Pd2+(aq) ---> 2 Sc3+(aq) + 2 Pd(s)

C) Sc3+(aq) + 3 Ag(s) ---> Sc(s) + 3 Ag+(aq)

d) Reactions a and c are spontaneous in the forward direction.

e) Reactions a, b and c are spontaneous in the forward direction.

f) None of the above

Please show work

Explanation / Answer

remember: The one with greater reduction potential (Eo) value will be reduced

2 Ag(s) + Pd2+(aq) ---> 2 Ag+(aq) + pd(s)

Here:

here Pd2+ is getting reduced

So,

Eo Pd > Eo Ag

Ga(s) + 3Ag+(aq) ---> Ga3+(aq) + 3Ag(s)

Here:

here Ag+ is getting reduced

So,

Eo Ag > Eo Ga

Sc(s) + Ga3+(aq) ---> Sc3+(aq) + Ga(s)

Here:

here Ga3+ is getting reduced

So,

Eo Ga > Eo Sc

Form above 3 reaction, order of Eo are:

Eo Pd > Eo Ag > Eo Ga > Eo Sc. ……. relation 1

Now lets go to the given reactions:

A)3Pd(s) + 2Ga3+(aq)---> 3Pd2+(qq) + 2Ga(s)

Here:

here Ga3+ is getting reduced

So for this reaction to be spontaneous

Eo Ga > Eo Pd

which is not correct from relation 1.

So, this is not spontaneous

B)2Sc(s) + 2Pd2+(aq) ---> 2 Sc3+(aq) + 2 Pd(s)

Here:

here Pd2+ is getting reduced

So for this reaction to be spontaneous

Eo Pd > Eo Sc

which is correct from relation 1.

So, this is spontaneous

C) Sc3+(aq) + 3 Ag(s) ---> Sc(s) + 3 Ag+(aq)

Here:

here Sc3+ is getting reduced

So for this reaction to be spontaneous

Eo Sc > Eo Ag

which is not correct from relation 1.

So, this is not spontaneous

Answer:

only B is spotaneous

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