Calculate Oh and Ph for 0.10 M Nabro

This calculator determines the hydroxide ion concentration (OH-) and pH for a 0.10 M sodium bromide (NaBr) solution. Sodium bromide is a weak electrolyte, meaning it dissociates only slightly in water, making it a useful example for understanding weak electrolyte behavior.

Introduction

When calculating OH- and pH for a weak electrolyte like NaBr, we need to consider the dissociation equilibrium. Sodium bromide is a salt that dissociates into sodium ions (Na+) and bromide ions (Br-) in water. The hydroxide ion concentration (OH-) and pH are determined by the water's self-ionization equilibrium.

Key Concepts

Weak electrolytes dissociate only partially in water
The hydroxide ion concentration (OH-) is determined by water's self-ionization
pH is calculated from the hydroxide ion concentration

How to Use This Calculator

Enter the concentration of NaBr in molarity (M)
Click "Calculate" to compute the OH- concentration and pH
Review the results and interpretation
Use the "Reset" button to clear inputs

Formula Used

For a weak electrolyte like NaBr, the hydroxide ion concentration (OH-) is determined by water's self-ionization equilibrium:

Water Self-Ionization

H₂O ⇌ H⁺ + OH^-

K_w = [H⁺][OH^-] = 1.0 × 10^-14 at 25°C

The pH is calculated from the hydroxide ion concentration:

pH Calculation

pH = -log[OH^-]

Worked Example

Let's calculate the OH- concentration and pH for a 0.10 M NaBr solution:

Since NaBr is a weak electrolyte, it doesn't significantly affect the water's self-ionization equilibrium
The OH- concentration remains approximately equal to the square root of K_w
OH- = √(1.0 × 10^-14) = 1.0 × 10^-7 M
pH = -log(1.0 × 10^-7) = 7.0

Note: The NaBr concentration has a negligible effect on the OH- concentration for weak electrolytes.

Interpreting Results

The results show that for a 0.10 M NaBr solution:

The hydroxide ion concentration is 1.0 × 10^-7 M
The pH is 7.0, indicating a neutral solution
The solution behaves similarly to pure water

This is expected because NaBr is a weak electrolyte and doesn't significantly affect the water's self-ionization equilibrium.

Frequently Asked Questions

Does the NaBr concentration affect the OH- concentration?: For weak electrolytes like NaBr, the concentration has a negligible effect on the OH- concentration.
Why is the pH 7.0 for a 0.10 M NaBr solution?: The pH is 7.0 because the solution behaves similarly to pure water, with equal concentrations of H+ and OH- ions.
Can this calculator be used for other weak electrolytes?: Yes, the same principles apply to other weak electrolytes, though the exact dissociation may vary.
What is the significance of K_w in this calculation?: K_w represents the water's self-ionization constant and is essential for determining the OH- concentration.