Question

Is the following a redox reaction? Explain. $$ \mathrm{NH}_{3}(a q)+\mathrm{HCl}(a q) \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}(a q) $$

Short answer

No, it is not a redox reaction because there are no changes in the oxidation states of the elements involved.

Step-by-step solution

Identify Oxidation States

Determine the oxidation states of each element in the reactants and products. For \(\text{NH}_3\), nitrogen (N) has an oxidation state of -3 and each hydrogen (H) is +1. For \(\text{HCl}\), hydrogen (H) is +1 and chlorine (Cl) is -1. For \(\text{NH}_4\text{Cl}\), nitrogen (N) is -3, each hydrogen (H) is +1, and chlorine (Cl) is -1.

Compare Oxidation States

Compare the oxidation states of each element in the reactants and products. In \(\text{NH}_3\), N is -3 and remains -3 in \(\text{NH}_4\text{Cl}\). The H atoms are also +1 in both reactants and products. Cl remains -1 in both \(\text{HCl}\) and \(\text{NH}_4\text{Cl}\).

Determine If Redox Reaction

A redox reaction involves a change in oxidation states. Since there are no changes in the oxidation states of nitrogen, hydrogen, or chlorine between reactants and products, this reaction is not a redox reaction.

Key concepts

Oxidation States

The concept of oxidation states is crucial in understanding redox reactions. Every atom in a molecule has an oxidation state, which represents its degree of oxidation or reduction. For instance, in ammonia (\(\text{NH}_3\)), nitrogen has an oxidation state of -3, while each hydrogen has +1. It's important to assign oxidation states correctly to determine if electrons are transferred in a reaction.
To find these states:

• For simple ions, the oxidation state is equal to the charge.
• For hydrogen, it's usually +1, and for oxygen, it’s usually -2 (with exceptions).
• In molecules, the sum of oxidation states must equal the overall charge of the molecule. For example, in \(\text{HCl}\), hydrogen is +1 and chlorine is -1.

Properly calculating oxidation states helps in identifying the transfer of electrons and thus determining redox reactions.

Reaction Analysis

Analyzing a reaction involves breaking down each reactant and product's oxidation states. This helps in identifying whether there is a change in these states.
For the reaction given in the exercise: \[\mathrm{NH}_{3}(aq)+\mathrm{HCl}(aq) \longrightarrow \mathrm{NH}_{4}\mathrm{Cl}(aq)\]
First, determine the oxidation states:

• For \(\text{NH}_3\), nitrogen is -3, and hydrogen is +1.
• In \(\text{HCl}\), hydrogen is +1 and chlorine is -1.
• In the product \(\text{NH}_4\text{Cl}\), nitrogen remains -3, hydrogen remains +1, and chlorine remains -1.

Comparing these, you’ll see all oxidation states stay the same.
This means there is no transfer of electrons, indicating that this specific reaction is not a redox reaction.
Effective reaction analysis is key in determining the nature of any given chemical reaction.

Chemical Reactions

Chemical reactions involve the transformation of reactants into products, following specific rules and conditions. They can be classified into different types, such as redox, acid-base, and precipitation reactions.
In a redox (reduction-oxidation) reaction:

• There is a transfer of electrons between substances.
• One substance gets oxidized (loses electrons), and another gets reduced (gains electrons).

For the exercise problem, we analyzed the chemical reaction: \[\mathrm{NH}_{3}(aq)+\mathrm{HCl}(aq) \longrightarrow \mathrm{NH}_{4}\mathrm{Cl}(aq)\]
Since there are no changes in the oxidation states of any element here, this is not a redox reaction.
Chemical reactions need to be carefully studied for changes in oxidation states to properly classify them as redox or non-redox reactions, ensuring a deeper understanding of the process and its impacts.