Calculate Ph of 0.05 M Nah2po4

Introduction

Sodium dihydrogen phosphate (NaH₂PO₄) is a weak acid that dissociates in water to form H₂PO₄⁻ and H⁺ ions. The pH of a solution containing this compound can be calculated using the dissociation constant (Kₐ) and the concentration of the acid.

This calculator provides an accurate pH determination for a 0.05 M NaH₂PO₄ solution, considering the dissociation behavior of the weak acid. The calculation follows standard chemical equilibrium principles and provides a reliable estimate of the solution's acidity.

How to Calculate pH

To calculate the pH of a 0.05 M NaH₂PO₄ solution, follow these steps:

1. Determine the dissociation constant (Kₐ) for NaH₂PO₄. The Kₐ for NaH₂PO₄ is approximately 6.2 × 10⁻³ at 25°C.
2. Calculate the concentration of H⁺ ions using the dissociation equilibrium.
3. Convert the H⁺ concentration to pH using the pH formula.

The calculator automates these steps, providing a quick and accurate result.

Formula

The calculator uses this exact formula to determine the pH of the solution.

Example Calculation

Let's calculate the pH of a 0.05 M NaH₂PO₄ solution step by step:

1. Given: [NaH₂PO₄] = 0.05 M, Kₐ = 6.2 × 10⁻³
2. Assume x = [H⁺] = [H₂PO₄⁻]
3. Equation: 6.2 × 10⁻³ = x² / (0.05 - x)
4. Solve the quadratic equation: x² + (6.2 × 10⁻³)x - (3.1 × 10⁻³) = 0
5. Using the quadratic formula: x ≈ 0.056 M
6. Calculate pH: pH = -log₁₀(0.056) ≈ 1.25

This example demonstrates the calculation process, which the calculator performs automatically.

Interpreting Results

The calculated pH of approximately 1.25 indicates that the 0.05 M NaH₂PO₄ solution is acidic. This is expected because NaH₂PO₄ is a weak acid that partially dissociates in water, releasing H⁺ ions.

In practical terms, this means the solution has a relatively high concentration of hydrogen ions, which can affect the behavior of other substances added to it. The pH value provides a quantitative measure of the solution's acidity.