Calculate Ph for 2.0 10 3 M Sr Oh 2

This calculator determines the pH of a solution containing 2.0 × 10⁻³ M Sr(OH)₂. The calculation follows standard acid-base chemistry principles, assuming complete dissociation of the strong base.

How to Calculate pH

The pH of a solution is calculated using the concentration of hydrogen ions (H⁺). For strong bases like Sr(OH)₂, the pH can be determined directly from the concentration of the hydroxide ions (OH⁻).

Key Steps

Determine the concentration of hydroxide ions (OH⁻) from the given concentration of Sr(OH)₂.
Calculate the concentration of hydrogen ions (H⁺) using the relationship between H⁺ and OH⁻ in water.
Convert the H⁺ concentration to pH using the logarithmic pH scale.

For a strong base like Sr(OH)₂, the concentration of OH⁻ is equal to the concentration of Sr(OH)₂ because the base fully dissociates in water.

pH Formula

The pH is calculated using the following formula:

pH = -log₁₀[H⁺]

Where [H⁺] is the concentration of hydrogen ions in moles per liter (M).

For solutions of strong bases, the concentration of H⁺ can be calculated from the concentration of OH⁻ using the ion product of water:

[H⁺] × [OH⁻] = 1.0 × 10⁻¹⁴

For Sr(OH)₂, [OH⁻] = [Sr(OH)₂] = 2.0 × 10⁻³ M.

Worked Example

Let's calculate the pH for a solution with 2.0 × 10⁻³ M Sr(OH)₂.

Step 1: Determine [OH⁻]

Since Sr(OH)₂ is a strong base, [OH⁻] = [Sr(OH)₂] = 2.0 × 10⁻³ M.

Step 2: Calculate [H⁺]

Using the ion product of water:

[H⁺] = 1.0 × 10⁻¹⁴ / [OH⁻] = 1.0 × 10⁻¹⁴ / 2.0 × 10⁻³ = 5.0 × 10⁻¹² M

Step 3: Calculate pH

pH = -log₁₀[H⁺] = -log₁₀(5.0 × 10⁻¹²) = 11.30

The calculated pH is 11.30, indicating a strongly alkaline solution.

Interpreting Results

A pH of 11.30 indicates a very basic solution. This is typical for strong base solutions like Sr(OH)₂. The result shows that the solution is significantly alkaline, which is expected for strong bases.

Key Points

Strong bases like Sr(OH)₂ fully dissociate in water.
The pH of a strong base solution is always greater than 7.
Higher concentrations of strong bases result in higher pH values.

FAQ

What is the pH of a 2.0 × 10⁻³ M Sr(OH)₂ solution?

The pH is 11.30, indicating a strongly alkaline solution.

How is pH calculated for strong bases?

For strong bases, pH is calculated using the concentration of hydroxide ions and the ion product of water.

Why is the pH of Sr(OH)₂ solutions high?

Sr(OH)₂ is a strong base that fully dissociates, producing a high concentration of hydroxide ions, which lowers the concentration of hydrogen ions and increases pH.