Question

Is the reaction $$ \mathrm{NaCl}(\mathrm{aq})+\mathrm{AgNO}_{3}(\mathrm{aq}) \rightarrow \mathrm{NaNO}_{3}(\mathrm{aq})+\mathrm{AgCl}(\mathrm{s}) $$ an oxidation-reduction reaction? Explain your answer.

Short answer

The reaction is not an oxidation-reduction reaction as there are no changes in oxidation states.

Step-by-step solution

Define Oxidation-Reduction Reaction

An oxidation-reduction (redox) reaction involves the transfer of electrons between two species. One substance will lose electrons (oxidation) and another substance will gain electrons (reduction). To determine if a given reaction is redox, we need to analyze the change in oxidation states of the elements involved in the reaction.

Assign Oxidation States - Reactants

For the reactants, assign oxidation states: - In NaCl, the oxidation state of Na is +1 and Cl is -1. - In AgNO_3, the oxidation state of Ag is +1, N is +5, and O is -2.

Assign Oxidation States - Products

For the products, assign oxidation states: - In NaNO_3, the oxidation state of Na is +1, N is +5, and O is -2. - In AgCl, the oxidation state of Ag is +1 and Cl is -1.

Compare Oxidation States

Compare the oxidation states of each element on the reactants side with those on the products side: - Na goes from +1 in NaCl to +1 in NaNO_3 (no change). - Cl goes from -1 in NaCl to -1 in AgCl (no change). - Ag goes from +1 in AgNO_3 to +1 in AgCl (no change). - N goes from +5 in AgNO_3 to +5 in NaNO_3 (no change). - O stays the same at -2 in both AgNO_3 and NaNO_3 (no change).

Analyze the Results

Since there are no changes in oxidation states of any elements from reactants to products, there is no transfer of electrons. This means that the reaction does not involve oxidation and reduction, confirming that the reaction is not an oxidation-reduction reaction.

Key concepts

Oxidation States

Understanding oxidation states is key to analyzing chemical reactions, especially when identifying redox reactions. Oxidation states indicate the degree of oxidation of an atom within a compound. They help us determine how electrons are distributed among the different atoms.
To assign oxidation states, we follow some basic rules:

• Elements in their natural state have an oxidation state of zero.


• The oxidation state for a monatomic ion is equal to its charge, such as +1 for Na⁺ in NaCl.


• The sum of oxidation states in a neutral compound must be zero, and in an ion, it must equal the charge of the ion.

These steps are helpful for analyzing reactions. In our example reaction:

• In both the reactants and products, Na, Cl, Ag, N, and O retain their oxidation states.
• There is no change in their oxidation states.

Hence, since the oxidation states remain constant for all elements throughout the reaction, it is not a redox reaction.

Electron Transfer

In chemistry, electron transfer refers to the movement of electrons from one element or compound to another. This process is the hallmark of redox reactions, where one species loses electrons and another gains them.
For a redox reaction to occur:

• One reacting species must undergo oxidation, losing electrons.


• Another species must undergo reduction, gaining electrons.

In the reaction given:

• NaCl and AgNO₃ are the reactants, and NaNO₃ and AgCl are the products.


• Each element retains its original oxidation state from reactants to products, meaning no electrons have been transferred.

Because there's a lack of electron transfer between species, no oxidation or reduction takes place. Therefore, this reaction is not driven by electron transfer.

Redox Reactions

Redox reactions, short for oxidation-reduction reactions, are fundamental in chemistry due to their role in energy transfer, metallurgy, and biological processes. In these reactions, there's always an exchange of electrons between participating molecules.
The defining characteristics include:

• Oxidation: A process where a substance loses electrons.


• Reduction: A process where a substance gains electrons.


• Any substance that provides electrons is called a reducing agent, and the one that gains electrons is an oxidizing agent.

After analyzing the given reaction NaCl(aq) + AgNO₃(aq) → NaNO₃(aq) + AgCl(s), all elements show unchanged oxidation states throughout the reaction.
Because redox reactions are characterized by changes in oxidation states through electron exchange, and no such change occurs in this scenario, the reaction does not fit the criteria for a redox reaction. Therefore, no redox behavior is exhibited in this particular chemical process.