Calculate The Ph Of An Aqueous Solution Of 0.1 M Na3po4

Hydrolysis of Na₃PO₄ to PO₄³⁻:

\[ pH \approx pKa_3 + \log\left(\frac{1}{\sqrt{K_w \times Ka_3 \times C}}\right) \]

pH:

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1. What is the pH Calculation for Na₃PO₄ Solution?

The pH calculation for sodium phosphate (Na₃PO₄) solution involves determining the hydrolysis of the phosphate ion (PO₄³⁻) in water. As a salt of a weak acid (H₃PO₄) and strong base (NaOH), Na₃PO₄ undergoes hydrolysis, producing a basic solution.

2. How Does the Calculator Work?

The calculator uses the hydrolysis formula:

\[ pH \approx pKa_3 + \log\left(\frac{1}{\sqrt{K_w \times Ka_3 \times C}}\right) \]

Where:

\( pKa_3 \) — Negative logarithm of the third acid dissociation constant of phosphoric acid
\( K_w \) — Water ionization constant (1×10⁻¹⁴)
\( Ka_3 \) — Third acid dissociation constant of phosphoric acid
\( C \) — Concentration of Na₃PO₄ solution (mol/L)

Explanation: The formula accounts for the hydrolysis of PO₄³⁻ ions and the basic nature of the resulting solution.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for understanding the chemical behavior of phosphate solutions, which are important in biological systems, industrial processes, and laboratory applications.

4. Using the Calculator

Tips: Enter pKa₃ value (typically 12.35 for phosphoric acid) and concentration in mol/L. The calculator will compute the pH of the Na₃PO₄ solution.

5. Frequently Asked Questions (FAQ)

Q1: Why is Na₃PO₄ solution basic?
A: Na₃PO₄ is the salt of a weak acid (H₃PO₄) and strong base (NaOH). The phosphate ion (PO₄³⁻) undergoes hydrolysis with water, producing OH⁻ ions and making the solution basic.

Q2: What is the typical pKa₃ value for phosphoric acid?
A: The third dissociation constant pKa₃ for phosphoric acid is typically 12.35 at 25°C.

Q3: How does concentration affect the pH?
A: Higher concentrations of Na₃PO₄ generally result in higher pH values due to increased hydrolysis of phosphate ions.

Q4: Are there limitations to this calculation?
A: This calculation assumes ideal behavior and may not account for ionic strength effects or temperature variations beyond standard conditions.

Q5: What are common applications of Na₃PO₄ solutions?
A: Sodium phosphate solutions are used as buffers in biological research, cleaning agents, water treatment, and food processing.