What element is undergoing reduction (if any) in the following reaction?
[tex]Zn(s)+2 AgNO_3(aq) \rightarrow Zn(NO_3)_2(aq)+2 Ag(s)[/tex]
A. Zn
B. Ag
C. O
D. N
E. This is not an oxidation-reduction reaction.
Answer (2)
In the reaction Z n ( s ) + 2 A g N O 3 ( a q ) → Z n ( N O 3 ) 2 ( a q ) + 2 A g ( s ) , silver (Ag) is the element undergoing reduction, as its oxidation state decreases from +1 to 0. Therefore, the correct answer is B. Ag.
;
Zinc (Zn) is oxidized as its oxidation state increases from 0 to +2.
Silver (Ag) is reduced as its oxidation state decreases from +1 to 0.
Nitrogen (N) and Oxygen (O) do not undergo a change in oxidation state.
Therefore, the element undergoing reduction is A g .
Explanation
Understanding Reduction We are asked to identify the element that is undergoing reduction in the given chemical reaction, if any. Reduction is the process where an element gains electrons, which results in a decrease in its oxidation state. To determine this, we need to compare the oxidation states of each element before and after the reaction.
Determining Oxidation States The given reaction is: Z n ( s ) + 2 A g N O 3 ( a q ) → Z n ( N O 3 ) 2 ( a q ) + 2 A g ( s ) Let's determine the oxidation states of each element in the reactants and products:
Zinc (Zn): In the reactant side, Zn is in its elemental form, so its oxidation state is 0. In the product side, it is part of Z n ( N O 3 ) 2 . The nitrate ion ( N O 3 − ) has a charge of -1, so two nitrate ions have a total charge of -2. Therefore, the oxidation state of Zn in Z n ( N O 3 ) 2 is +2.
Silver (Ag): In the reactant side, Ag is part of A g N O 3 . The nitrate ion ( N O 3 − ) has a charge of -1, so the oxidation state of Ag in A g N O 3 is +1. In the product side, Ag is in its elemental form, so its oxidation state is 0.
Nitrogen (N): In the reactant side, N is part of A g N O 3 . The oxidation state of oxygen is usually -2. Since there are three oxygen atoms, the total negative charge is -6. The nitrate ion has a charge of -1, so the oxidation state of N must be +5. In the product side, N is part of Z n ( N O 3 ) 2 . The oxidation state of oxygen is still -2, so the oxidation state of N is still +5.
Oxygen (O): The oxidation state of oxygen is -2 in both A g N O 3 and Z n ( N O 3 ) 2 .
Identifying the Element Undergoing Reduction Now, let's compare the oxidation states:
Zn: 0 to +2 (oxidation state increased, so it is oxidized)
Ag: +1 to 0 (oxidation state decreased, so it is reduced)
N: +5 to +5 (oxidation state remained the same)
O: -2 to -2 (oxidation state remained the same) Since the oxidation state of Ag decreases from +1 to 0, it is undergoing reduction.
Final Answer Therefore, the element undergoing reduction in the reaction is silver (Ag).
Examples
In the refining of precious metals, understanding reduction-oxidation reactions is crucial. For example, silver is often extracted from its ores using a process that involves reduction of silver ions to metallic silver. This process is similar to the reaction described in the problem, where silver ions in solution are reduced to solid silver. The ability to identify which element is being reduced allows chemists to optimize the extraction process and improve the yield of the desired metal.
