Question

(a) Write the intact-compound equation and the net ionic equation for the neutralization reaction that occurs between aqueous solutions of sulfuric acid and potassium hydroxide. (b) What salt would be isolated if you evaporated the water from this solution after neutralization?

Short answer

a) The intact-compound equation is: \(H_2SO_4(aq) + 2KOH(aq) → K_2SO_4(aq) + 2H_2O(l)\) The net ionic equation is: \(H^+(aq) + OH^-(aq) → H_2O(l)\) b) The salt isolated after evaporating the water from the solution is potassium sulfate (K₂SO₄).

Step-by-step solution

Write the balanced chemical equation

To write the intact-compound equation, we need to combine the reactants (sulfuric acid and potassium hydroxide) to form the products (a salt and water). The balanced chemical equation is: H₂SO₄(aq) + 2KOH(aq) → K₂SO₄(aq) + 2H₂O(l) #a. Net ionic equation#

Write the ionic equation

Write down the dissociated ions of each species in the aqueous solution: H₂SO₄(aq) → 2H⁺(aq) + SO₄²⁻(aq) 2KOH(aq) → 2K⁺(aq) + 2OH⁻(aq)

Cancel spectator ions

In this case, there are no spectator ions, as all ions participate in the reaction.

Write the net ionic equation

Now we can write the net ionic equation by combining ions that react with each other to form the products: 2H⁺(aq) + SO₄²⁻(aq) + 2K⁺(aq) + 2OH⁻(aq) → K₂SO₄(aq) + 2H₂O(l) Simplifying the net ionic equation gives: 2H⁺(aq) + 2OH⁻(aq) → 2H₂O(l) This can be further simplified by dividing everything by 2: H⁺(aq) + OH⁻(aq) → H₂O(l) #b. Salt isolated after evaporating the water#

Identify the salt

After evaporating the water from the solution after neutralization, the remaining salt is the product of the neutralization reaction, potassium sulfate (K₂SO₄).

Key concepts

Chemical Equations

Chemical equations are representations of chemical reactions where the reactants are shown on the left, the products on the right, and an arrow separates the two, indicating the direction of the reaction. A properly balanced chemical equation has equal numbers of each type of atom on both sides, ensuring the law of conservation of mass is followed.

For our neutralization reaction between sulfuric acid \( H_2SO_4 \) and potassium hydroxide \( KOH \) to produce potassium sulfate \( K_2SO_4 \) and water (H2O), the equation is:
\[ H_2SO_4(aq) + 2KOH(aq) \rightarrow K_2SO_4(aq) + 2H_2O(l) \]
This shows the reactants transforming into the products, with every atom accounted for in the products.

Net Ionic Equations

Net ionic equations distill a chemical reaction down to only the constituents involved in the actual change. It strips away the spectator ions which do not take part in the reaction. These equations are useful in highlighting the essence of a chemical reaction.

To derive the net ionic equation from the full chemical equation, you first write down the full ionic equation:
\[ 2H^+(aq) + SO_4^{2-}(aq) + 2K^+(aq) + 2OH^-(aq) \rightarrow K_2SO_4(aq) + 2H_2O(l) \]
Since all ions take part in the reaction, we get our net ionic equation by combining the hydrogen ions \( H^+ \) with the hydroxide ions \( OH^- \) to form water:
\[ H^+(aq) + OH^-(aq) \rightarrow H_2O(l) \]

This demonstrates that the essence of this neutralization reaction is the combination of an acid (\( H^+ \) ions) with a base (\( OH^- \) ions) to produce water.

Acid-Base Reactions

Acid-base reactions, or neutralization reactions, occur when an acid and a base react to form water and a salt. The acid donates \( H^+ \) ions, while the base provides \( OH^- \) ions that combine to create water (\( H_2O \) molecules), a product that typically signifies a neutralization reaction.

In our example, sulfuric acid (a strong acid) donates \( H^+ \) ions, and potassium hydroxide (a strong base) provides \( OH^- \) ions. They react to neutralize each other and produce water and the salt potassium sulfate as the products.
\[ H^+(aq) + OH^-(aq) \rightarrow H_2O(l) \]
These reactions are essential in many chemical processes and are paramount in understanding the behavior of acids and bases in solution.

Potassium Sulfate

Potassium sulfate \( K_2SO_4 \) is the salt formed when sulfuric acid neutralizes potassium hydroxide. In our reaction, after the neutralization process and after water is produced, potassium sulfate remains in solution initially. Upon evaporation of the water, the potassium sulfate can be isolated as a solid.

As a compound, potassium sulfate is used in various applications including fertilizers due to its potassium content, considered essential for plant growth. The compound is composed of two potassium (\( K^+ \) ions) and one sulfate (\( SO_4^{2-} \) ion) and dissolves readily in water to form these ions.

Spectator Ions

Spectator ions are ions in a chemical reaction that exist in the same form on both the reactant and product side of a chemical equation. As they do not participate in the actual reaction, they are not included in the net ionic equation.

In some reaction equations, such as the neutralization reaction we are considering, there are no spectator ions because all ions react to form the product. However, if any were present, they would be cancelled out when writing the net ionic equation. Understanding the role of spectator ions is crucial in simplifying equations and focusing on the change that occurs during a chemical reaction.