Question

Distinguish between a complete ionic equation and a net ionic equation.

Short answer

A complete ionic equation includes all ions involved in a reaction, including spectator ions that do not participate actively in the reaction. On the other hand, a net ionic equation is a simplified version that only shows the ions directly involved in the reaction, excluding spectator ions. For example, in the reaction between NaCl and AgNO₃, the complete ionic equation is Na⁺(aq) + Cl⁻(aq) + Ag⁺(aq) + NO₃⁻(aq) → Na⁺(aq) + NO₃⁻(aq) + AgCl(s), while the net ionic equation is Cl⁻(aq) + Ag⁺(aq) → AgCl(s).

Step-by-step solution

Understanding what an ionic equation is

An ionic equation is a chemical equation that represents the interaction between ionic compounds in a reaction. In an ionic equation, the ionic compounds are broken down into their constituent ions, making it easier to see the reactants and products. Ionic equations are commonly used in reactions involving soluble salts, acids, and bases.

Introducing the complete ionic equation

A complete ionic equation is a way of representing an ionic reaction by including all of the ions, including spectator ions, in the equation. Spectator ions are ions that do not actively participate in the reaction, but are simply present in the solution. In the complete ionic equation, both reactants and products are shown as dissociated ions.

Example of a complete ionic equation

Let's consider a reaction between sodium chloride (NaCl) and silver nitrate (AgNO₃) which forms silver chloride (AgCl) and sodium nitrate (NaNO₃). The complete ionic equation for this reaction is shown below: Na⁺(aq) + Cl⁻(aq) + Ag⁺(aq) + NO₃⁻(aq) → Na⁺(aq) + NO₃⁻(aq) + AgCl(s) This equation includes all ions involved in the reaction, even the spectator ions (Na⁺ and NO₃⁻).

Introducing the net ionic equation

A net ionic equation is a more simplified form of an ionic equation that shows only the ions that actively participate in the chemical reaction, excluding spectator ions. In other words, it only includes the ions that undergo a change during the reaction.

Example of a net ionic equation

For the reaction between sodium chloride (NaCl) and silver nitrate (AgNO₃), the net ionic equation will look like this: Cl⁻(aq) + Ag⁺(aq) → AgCl(s) In this equation, only the ions actively involved in the reaction (Cl⁻ and Ag⁺) are shown, and the spectator ions (Na⁺ and NO₃⁻) are excluded.

Differences between complete and net ionic equations

Compare the two examples from Steps 3 and 5. In the complete ionic equation, all ions in the reaction, including spectator ions, are listed. In the net ionic equation, only the ions directly involved in the reaction are shown. The main differences are: 1. The complete ionic equation shows all ions present, while the net ionic equation only shows the ions that change during the reaction. 2. The net ionic equation is a simplified version of the complete ionic equation, with spectator ions removed. By understanding these differences, you can better distinguish between a complete ionic equation and a net ionic equation in future chemistry problems.

Key concepts

complete ionic equation

In chemistry, when dealing with reactions involving ionic compounds, a complete ionic equation is a valuable tool. This kind of equation shows all the ions present in a solution, including both those that participate in the reaction and those that do not. The inclusion of all ions helps us understand what is present in the reaction mixture at a given moment. This is particularly useful when studying aqueous solutions because it provides a complete snapshot of the chemical situation.

Take, for instance, the reaction between sodium chloride (NaCl) and silver nitrate (AgNO₃). In a complete ionic equation, both NaCl and AgNO₃ are broken down into their ionic constituents since they dissociate in water. So, you would represent all sodium ions (Na⁺), chloride ions (Cl⁻), silver ions (Ag⁺), and nitrate ions (NO₃⁻) in the equation. This comprehensive representation is crucial as it lays the groundwork for identifying what is actually happening in the reaction.

The complete ionic equation for this reaction is:

• Na⁺(aq) + Cl⁻(aq) + Ag⁺(aq) + NO₃⁻(aq) → Na⁺(aq) + NO₃⁻(aq) + AgCl(s)

By displaying all possible ions, complete ionic equations help visualize the chemical landscape and recognize which ions participate directly in forming the final products.

net ionic equation

A net ionic equation offers a clearer, simpler picture by focusing solely on the ions that partake in the chemical reaction. It eliminates spectator ions, which do not change throughout the reaction, thus highlighting only those ions undergoing a chemical transformation.

Continuing with the sodium chloride and silver nitrate example, in the net ionic equation, you include only the ions that contribute to the formation of the product. Silver ions (

1. Ag⁺

) and chloride ions (

1. Cl⁻

) combine to form insoluble silver chloride (AgCl). The net ionic equation nicely trims down the initial complete ionic equation, making it easier to see the core of the reaction.

The net ionic equation for AgCl's formation is:

• Cl⁻(aq) + Ag⁺(aq) → AgCl(s)

This version only involves the ions that interact directly. By stripping away the unessential parts, the net ionic equation becomes a more efficient tool for understanding and predicting the results of chemical reactions.

spectator ions

Spectator ions are like the audience members at a sports game. They are present but do not actively play in the game. In a complete ionic equation, spectator ions remain in their ionic form, unchanged before and after the reaction. Recognizing spectator ions is essential because it helps in simplifying the equation to a net ionic form.

In our ongoing example of the reaction between sodium chloride and silver nitrate, the spectator ions are sodium ions (

1. Na⁺

) and nitrate ions (

1. NO₃⁻

). They appear on both sides of the complete ionic equation but do not participate in forming the precipitate (AgCl).

Identifying these non-participating ions helps focus only on the ions that change to create the net ionic equation. By understanding spectator ions, you can better interpret reactions and foresee which ions can be removed from the equation without affecting the core chemical transformation. This clarity allows chemists to understand the essential components of a reaction more efficiently, enhancing their analysis and broadening their comprehension of chemical processes.