Calculate Ph of Alcl3 at 0.055 M

Introduction

Aluminum chloride (AlCl₃) is a common inorganic compound used in various industrial applications. When dissolved in water, it dissociates completely into aluminum ions (Al³⁺) and chloride ions (Cl⁻). The presence of these ions affects the pH of the solution, which can be calculated using the concept of acid-base equilibrium.

The pH of a solution is a measure of its acidity or basicity, defined as the negative logarithm of the hydronium ion (H₃O⁺) concentration. For a solution containing a strong acid like AlCl₃, the pH can be determined by considering the dissociation of water and the formation of hydronium ions.

Formula

The pH of a solution containing a strong acid can be calculated using the following formula:

Where [H₃O⁺] is the concentration of hydronium ions in moles per liter (M). For a solution of AlCl₃, the concentration of H₃O⁺ can be determined by considering the dissociation of water and the formation of hydronium ions.

The dissociation of water is represented by the equation:

The equilibrium constant for the dissociation of water is given by:

For a solution of AlCl₃, the concentration of H⁺ is increased due to the dissociation of the salt. The concentration of H₃O⁺ can be calculated using the following equation:

Where [AlCl₃] is the concentration of AlCl₃ in the solution.

Calculation

To calculate the pH of a 0.055 M AlCl₃ solution, follow these steps:

1. Determine the concentration of hydronium ions ([H₃O⁺]) using the formula:
   [H₃O⁺] = √(K_w × [AlCl₃])
2. Substitute the known values into the formula:
   [H₃O⁺] = √(1.0 × 10⁻¹⁴ × 0.055) = √(5.5 × 10⁻¹⁶) ≈ 7.42 × 10⁻⁹ M
3. Calculate the pH using the formula:
   pH = -log₁₀[H₃O⁺] = -log₁₀(7.42 × 10⁻⁹) ≈ 8.13

The pH of the 0.055 M AlCl₃ solution is approximately 8.13, indicating a basic solution.

Interpretation

The calculated pH of 8.13 for the 0.055 M AlCl₃ solution indicates that the solution is basic. This is because the dissociation of AlCl₃ increases the concentration of hydroxide ions (OH⁻) in the solution, which in turn increases the concentration of hydronium ions (H₃O⁺).

The pH value of 8.13 is relatively high, indicating that the solution is not strongly acidic or basic. The presence of Al³⁺ and Cl⁻ ions in the solution affects the pH, but the solution remains basic due to the dissociation of water.

It's important to note that the pH calculation assumes that AlCl₃ is a strong acid and dissociates completely in water. In reality, the dissociation may not be complete, and other factors such as temperature and ionic strength can affect the pH of the solution.