- The balanced equation is \(Cu(s) + 2AgNO_3(aq) \rightarrow Cu(NO_3)_2(aq) + 2Ag(s)\).
- Copper is oxidized as its oxidation number increases from 0 to +2, shown by the half-equation \(Cu(s) \rightarrow Cu^{2+}(aq) + 2e^-\).
- Silver ions are reduced as their oxidation number decreases from +1 to 0, shown by the half-equation \(Ag^+(aq) + e^- \rightarrow Ag(s)\).
Explanation
- Balanced Chemical Equation
The chemical reaction between copper metal and silver nitrate is a classic example of a single-displacement redox reaction. In this reaction, copper replaces silver from the silver nitrate solution. The balanced chemical equation for this process is:
\[Cu(s) + 2AgNO_3(aq) \rightarrow Cu(NO_3)_2(aq) + 2Ag(s)\]
This equation shows that one mole of solid copper reacts with two moles of aqueous silver nitrate to produce one mole of copper(II) nitrate and two moles of solid silver.
- Identification of Oxidation
To identify the species being oxidized, we track the change in oxidation number (O.N.). Oxidation is defined as an increase in the oxidation number, which corresponds to the loss of electrons.
- In the reactant, solid copper \(Cu(s)\) is in its elemental form, so its O.N. is 0.
- In the product, copper is part of the aqueous copper(II) nitrate \(Cu(NO_3)_2\), where it exists as a \(Cu^{2+}\) ion. Its O.N. is +2.
Since the O.N. of copper increased from 0 to +2, copper is the substance being oxidized. The oxidation half-equation is:
\[Cu(s) \rightarrow Cu^{2+}(aq) + 2e^-\]
- Identification of Reduction
Reduction is defined as a decrease in the oxidation number, which corresponds to the gain of electrons.
- In the reactant, silver is present in the \(AgNO_3\) solution as an \(Ag^+\) ion. Its O.N. is +1.
- In the product, solid silver \(Ag(s)\) is in its elemental form, so its O.N. is 0.
Since the O.N. of silver decreased from +1 to 0, silver ions are the substance being reduced. The reduction half-equation is:
\[Ag^+(aq) + e^- \rightarrow Ag(s)\]
Examples
This reaction is often used in science laboratories to demonstrate displacement reactions and the concept of electrochemical series. It serves as a visual example of how a more reactive metal (copper) can displace a less reactive metal (silver) from its salt solution. This principle is fundamental in fields such as metallurgy for extracting metals, electroplating processes, and the development of batteries where controlling redox reactions allows for the conversion of chemical energy into electrical energy.