Question #5d695

Feb 5, 2018

There will be no reaction with this combination.

Explanation:

This is an example of a redox reaction that is not spontaneous. The silver metal is a reducing agent, but a very weak one. This means it can cause to reduction of other substances (more about them later), by undergoing oxidation itself. However, being a weak reducing agent means it is difficult to oxidize.

The oxidation of silver metal is written

$A g \rightarrow A {g}^{+} + {e}^{-}$

The electrode potential that goes with this process is $+ 0.80 V$ (the V stands for volts of electric potential. You look this up it a table, like the one here: http://www.chemeddl.org/services/moodle/media/QBank/GenChem/Tables/EStandardTable.htm).

For this to happen, however, we require an oxidizing agent - one that is quite strong, because Ag is difficult to oxidize. The only oxidizing agents in this question are lead ion, $P {b}^{2 +}$ and nitrate ion, $N {O}_{3}^{-}$. Note that an oxidizing agent is a substance that can be reduced.

Neither of these is sufficiently strong to cause the oxidation of the silver metal. Here is the proof:

The reduction of lead ion is given by:

$P {b}^{2 +} + 2 {e}^{-}$ $\rightarrow P b$

But, the potential for this is $- 0.13 V$

In order for a spontaneous reaction to occur, the value obtained by subtracting the potential for the oxidation $\left(+ 0.80 V\right)$ from that of the reduction $\left(- 0.13 V\right)$ must be a positive number.

In this case, it is

$- 0.13 V - \left(+ 0.80 V\right) = - 0.93 V$

a non-spontaneous reaction.

In a similar way, it can be shown that the nitrate ion is also not able to cause silver to oxidize (unless you provide a large concentration of ${H}^{+}$ ions, in which case you are really working with nitric acid - a very powerful oxidizer).