Question

Write the balanced equation, the complete ionic equation, and the net ionic equation for the reaction between aqueous potassium chloride and lead(II) nitrate that produces lead chloride and potassium nitrate.

Short answer

The short answer based on the step-by-step solution is: Balanced Equation: \(KCl(aq) + Pb(NO_3)_2(aq) \rightarrow PbCl_2(s) + KNO_3(aq)\) Complete Ionic Equation: \(K^+(aq) + Cl^-(aq) + Pb^{2+}(aq) + 2NO_3^-(aq) \rightarrow PbCl_2(s) + K^+(aq) + NO_3^-(aq)\) Net Ionic Equation: \(Cl^-(aq) + Pb^{2+}(aq) \rightarrow PbCl_2(s)\)

Step-by-step solution

Write the balanced equation

We are given the reactants and the products for the reaction. Thus, we can write the chemical equation as: KCl(aq) + Pb(NO₃)₂(aq) → PbCl₂(s) + KNO₃(aq) To balance the equation, we need to balance the numbers of each element on both sides of the arrow. It can be observed that the equation is already balanced, as we have one potassium (K), one lead (Pb), two chlorine (Cl), and two nitrate (NO₃) on both sides. So, the balanced equation is: KCl(aq) + Pb(NO₃)₂(aq) → PbCl₂(s) + KNO₃(aq)

Write the complete ionic equation

Now, we will write the complete ionic equation by breaking the soluble compounds into their constituent ions. Soluble compounds are those compounds which are present in aqueous solution (aq). In this case, KCl(aq), Pb(NO₃)₂(aq), and KNO₃(aq) are soluble. PbCl₂ is not soluble and forms a solid (s), so we won't break it down. In order to write the dissolved ionic compounds, we need to know their charges. Potassium has a +1 charge, chloride has a -1 charge, lead(II) has a +2 charge, and nitrate has a -1 charge. With this information, we can write the complete ionic equation as: K⁺(aq) + Cl⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) → PbCl₂(s) + K⁺(aq) + NO₃⁻(aq)

Write the net ionic equation

Now, we will remove the spectator ions, which are the ions present on both sides of the equation. In this case, K⁺(aq) and NO₃⁻(aq) are the spectator ions. After removing the spectator ions, we are left with the net ionic equation: Cl⁻(aq) + Pb²⁺(aq) → PbCl₂(s) This is the final net ionic equation for the reaction between aqueous potassium chloride and lead(II) nitrate that produces lead chloride and potassium nitrate.

Key concepts

Balancing Chemical Equations

Mastering the process of balancing chemical equations is essential when diving into the world of chemistry. It guarantees that the Law of Conservation of Mass is satisfied, meaning that matter is neither created nor destroyed during a chemical reaction. To achieve a balanced equation, every type of atom on the reactants side must be equal to the number of the same atoms on the products side. This is crucial for accurately predicting the amounts of products and reactants involved.

Consider the reaction where aqueous potassium chloride reacts with aqueous lead(II) nitrate. Starting with the unbalanced equation, we identify each element and tally their atoms on both sides. If there's an imbalance, we adjust coefficients—the numbers before compounds—until the equation is balanced. The exercise provided demonstrates a straightforward case where each atom's count is already equal on both sides, indicating that the reaction is balanced without further adjustment.

• Key Point: Coefficients must be whole numbers.
• Common mistake to avoid: Never change the subscripts in a chemical formula to balance an equation, as this changes the compound's identity.

Complete Ionic Equation

Once we have a balanced chemical equation, we progress to the complete ionic equation, showing all of the ions in an aqueous solution. Chemicals in their ionic form are written as individual cations and anions that result from the dissociation of soluble compounds in water. It's an exploratory step between the balanced molecular equation and the net ionic equation.

To write the complete ionic equation, we must consider the solubility of compounds. Soluble ionic compounds dissociate into their respective ions, while insoluble compounds, like solid precipitates, are written in their complete formula without dissociation. Through the example we have—potassium chloride and lead(II) nitrate in water—we write each soluble compound as separate ions, while the insoluble lead chloride remains intact. This breakdown provides an inclusive view of the reaction's ionic participants.

Insight:

Writing the complete ionic equation sharpens the understanding of reactions by revealing the actual ionic species involved, rather than just the compounds in their original form.

Net Ionic Equation

The net ionic equation is the simplified version of the complete ionic equation, focused solely on the ions that undergo a chemical change. It strips away the spectator ions—those that do not participate in the reaction—as they appear unchanged on both the reactant and product sides of the equation. Spectator ions are like bystanders: present at the scene but not engaging in the action.

In the example given, after writing the complete ionic equation, we identify potassium and nitrate ions as spectators because they are unchanged on both sides of the equation. Eliminating them highlights the essence of the reaction: chloride ions combining with lead(II) ions to form lead chloride. The net ionic equation thus communicates the core chemical change, which in this scenario, is the formation of a precipitate.

• Essential Idea: The net ionic equation includes only those compounds and ions that undergo chemical changes.
• Application Tip: Keep track of the charges and states of matter when writing net ionic equations to accurately represent the reaction.