A buffer solution is made by dissolving H₃PO₄ and NaH₂PO₄ in water.
b. Write an equation that shows how this buffer neutralizes added base.

Verified step by step guidance

1. Identify the components of the buffer solution: The buffer consists of H₃PO₄ (phosphoric acid, a weak acid) and NaH₂PO₄ (sodium dihydrogen phosphate, its conjugate base). This combination allows the buffer to neutralize added base or acid.
2. Understand the role of H₃PO₄: When a base is added to the buffer, the weak acid (H₃PO₄) donates a proton (H⁺) to neutralize the base, forming water and its conjugate base (H₂PO₄⁻).
3. Write the chemical equation for the reaction: The base (OH⁻) reacts with H₃PO₄ to form H₂PO₄⁻ and water. The equation is: $H_3{\mathrm{PO}}_4+{\mathrm{OH}}^{-}\to H_2{\mathrm{PO}}_4-+H_{2}O$
4. Explain the reaction: In this reaction, H₃PO₄ donates a proton (H⁺) to the hydroxide ion (OH⁻), neutralizing the base and forming water (H₂O). The remaining species, H₂PO₄⁻, is the conjugate base of H₃PO₄.
5. Conclude the buffer's function: This reaction demonstrates how the buffer resists changes in pH by neutralizing added base through the weak acid component (H₃PO₄).

Key Concepts

Buffer Solutions

A buffer solution is a special type of solution that resists changes in pH when small amounts of acid or base are added. It typically consists of a weak acid and its conjugate base, or a weak base and its conjugate acid. In this case, H₃PO₄ (phosphoric acid) acts as the weak acid, while NaH₂PO₄ (sodium dihydrogen phosphate) provides the conjugate base.

Neutralization Reaction

A neutralization reaction occurs when an acid reacts with a base to produce water and a salt. In the context of a buffer, when a base is added, the weak acid in the buffer donates protons (H⁺ ions) to neutralize the added hydroxide ions (OH⁻), thus maintaining the pH of the solution. This reaction is crucial for understanding how buffers function in resisting pH changes.

Equilibrium in Buffer Systems

Buffer systems operate based on the principles of chemical equilibrium, where the concentrations of the weak acid and its conjugate base adjust to counteract changes in pH. The equilibrium can be represented by the dissociation of the weak acid and the reaction with added base, illustrating how the buffer maintains a stable pH despite external changes. This dynamic balance is essential for the buffer's effectiveness.