Calculate H+ Ph Poh Nd Oh for 0.0060 M Hno3

This calculator helps determine the concentrations of H⁺, OH⁻, and the pH and pOH values for a 0.0060 M nitric acid (HNO₃) solution. It uses standard acid dissociation constants and water dissociation properties.

Introduction

When nitric acid (HNO₃) dissolves in water, it dissociates completely into hydronium ions (H₃O⁺ or H⁺) and nitrate ions (NO₃⁻). This complete dissociation makes HNO₃ a strong acid, meaning it fully donates its proton to water.

The pH of a solution is a measure of its acidity or basicity, calculated from the concentration of H⁺ ions. The pOH is calculated from the concentration of OH⁻ ions, and these two values are related through the water dissociation constant (Kw).

Formula

For a strong acid like HNO₃, the concentration of H⁺ ions is equal to the initial concentration of the acid:

[H⁺] = [HNO₃] = 0.0060 M

The pH is then calculated using the formula:

pH = -log[H⁺]

The concentration of OH⁻ ions can be found using the water dissociation constant (Kw = 1.0 × 10⁻¹⁴ at 25°C):

[OH⁻] = Kw / [H⁺] = 1.0 × 10⁻¹⁴ / 0.0060

The pOH is calculated similarly:

pOH = -log[OH⁻]

Example Calculation

For a 0.0060 M HNO₃ solution:

H⁺ concentration = 0.0060 M (since HNO₃ is a strong acid)
pH = -log(0.0060) ≈ 2.222
[OH⁻] = 1.0 × 10⁻¹⁴ / 0.0060 ≈ 1.67 × 10⁻¹² M
pOH = -log(1.67 × 10⁻¹²) ≈ 11.78

Note that pH + pOH = 14 for any aqueous solution.

Interpreting Results

A pH of 2.222 indicates this is a moderately acidic solution. The very low concentration of OH⁻ ions (1.67 × 10⁻¹² M) confirms the solution is acidic, as expected for a strong acid.

The pOH value of 11.78 is consistent with the pH value, as their sum is approximately 14.

Remember that for strong acids, the concentration of H⁺ ions is equal to the initial concentration of the acid. For weak acids, you would need to use the acid dissociation constant (Ka) to calculate the H⁺ concentration.

FAQ

Why does HNO₃ dissociate completely in water?

HNO₃ is a strong acid because its dissociation constant (Ka) is extremely large, meaning it almost completely donates its proton to water molecules.

What is the relationship between pH and pOH?

For any aqueous solution, pH + pOH = 14 at 25°C. This is because the product of [H⁺] and [OH⁻] is always equal to the water dissociation constant (Kw = 1.0 × 10⁻¹⁴).

How does temperature affect these calculations?

The water dissociation constant (Kw) changes with temperature. At 25°C, Kw = 1.0 × 10⁻¹⁴, but at other temperatures, you would need to use the appropriate Kw value.