Problem 56 - Chemistry Matter and Change

Question

Formulate Equations A reaction occurs when nitric acid (HNO \(_{3}\) ) is mixed with an aqueous solution of potassium hydrogen carbonate. Aqueous potassium nittrate is produced. Write the chemical and net ionic equations for the reaction.

Step-by-Step Solution

Answer

The balanced chemical equation for the reaction between nitric acid (HNO₃) and potassium hydrogen carbonate (KHCO₃) is: HNO₃ + KHCO₃ → KNO₃ + H₂O + CO₂ The net ionic equation for this reaction is: H⁺(aq) + HCO₃⁻(aq) → H₂O(l) + CO₂(g)

Step 1: Write the balanced chemical equation for the reaction

We start by writing the formulae for the reactants and products involved in the reaction. Nitric acid (HNO₃) + Potassium hydrogen carbonate (KHCO₃) → Aqueous potassium nitrate (KNO₃) + other products Now, we can balance the equation: HNO₃ + KHCO₃ → KNO₃ + H₂O + CO₂ This is the balanced chemical equation for the reaction.

Step 2: Identify ions present in the reactants and products

In order to write the ionic equation and the net ionic equation, we need to identify the ions present in the reactants and products. Reactants: - Nitric acid (HNO₃) dissociates into H⁺ and NO₃⁻ ions. - Potassium hydrogen carbonate (KHCO₃) dissociates into K⁺ and HCO₃⁻ ions. Products: - Aqueous potassium nitrate (KNO₃) dissociates into K⁺ and NO₃⁻ ions. - Water (H₂O) does not dissociate. - Carbon dioxide (CO₂) does not dissociate.

Step 3: Write the ionic equation for the reaction

Now write the ionic equation by listing the ions in the reactants and products identified in Step 2: H⁺(aq) + NO₃⁻(aq) + K⁺(aq) + HCO₃⁻(aq) → K⁺(aq) + NO₃⁻(aq) + H₂O(l) + CO₂(g)

Step 4: Identify and cancel out spectator ions to obtain the net ionic equation

Spectator ions are ions that do not change during the reaction and can be found in both reactants and products. In this case, potassium (K⁺) and nitrate (NO₃⁻) ions are spectator ions. We can now cancel them out to write the net ionic equation: H⁺(aq) + HCO₃⁻(aq) → H₂O(l) + CO₂(g) This is the net ionic equation for the reaction between nitric acid and potassium hydrogen carbonate.

Key Concepts

Balanced Chemical Equation

A balanced chemical equation is a way to represent a chemical reaction with the same number of each type of atom on both sides of the equation. This is essential to satisfy the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
To balance a chemical equation, you need to ensure that each element has the same number of atoms on the reactant side as on the product side.

• Step-by-step process: Start by counting the number of each type of atom in the reactants and products. Adjust coefficients, which are the numbers placed before the compounds, to balance the equation.
• Example: The balanced equation for the reaction between nitric acid and potassium hydrogen carbonate is:
  \[\text{HNO}_3 + \text{KHCO}_3 \rightarrow \text{KNO}_3 + \text{H}_2\text{O} + \text{CO}_2\]

Balancing chemical equations ensures that all atoms are accounted for and the reaction follows the laws of chemistry.

Ionic Equation

An ionic equation shows dissolved ionic compounds as ions. This type of equation highlights the ions that are involved in the reaction, helping students and chemists better understand the chemical process at the ionic level.
When writing an ionic equation, compounds that dissolve in water and dissociate into ions are expressed as ions. For example:

• Reactant Example: Nitric acid (HNO₃) dissociates into \( \text{H}^+ \) and \( \text{NO}_3^- \) ions when in solution.
• Product Example: Potassium nitrate (KNO₃) dissolves into \( \text{K}^+ \) and \( \text{NO}_3^- \) ions.

The full ionic equation for our example is:
\[\text{H}^+(aq) + \text{NO}_3^-(aq) + \text{K}^+(aq) + \text{HCO}_3^-(aq) \rightarrow \text{K}^+(aq) + \text{NO}_3^-(aq) + \text{H}_2\text{O}(l) + \text{CO}_2(g)\]
By focusing on ions, ionic equations help visualize and understand the reaction dynamics.

Net Ionic Equation

The net ionic equation provides a more simplified view of the reaction by removing spectator ions. Spectator ions are ions that do not participate in the actual chemical change and remain unchanged in solution.
You can find spectator ions on both sides of the ionic equation. By eliminating them, the net ionic equation only shows the ions and molecules that directly participate in the reaction.

• Steps to identifying: Identify the ions present on both sides of the ionic equation that do not change during the reaction.
• Example: Potassium (\( \text{K}^+ \)) and nitrate ions (\( \text{NO}_3^- \)) are spectator ions in our solution.

After removing the spectator ions, the net ionic equation for nitric acid reacting with potassium hydrogen carbonate is:
\[\text{H}^+(aq) + \text{HCO}_3^-(aq) \rightarrow \text{H}_2\text{O}(l) + \text{CO}_2(g)\]
This simplified form emphasizes the core reactions happening during the process, aiding clearer understanding.