Calculate Ksp for Silver Bromide Given The Following Data

The solubility product constant (KSP) is a fundamental concept in chemistry that quantifies the solubility of a sparingly soluble salt. For silver bromide (AgBr), calculating KSP helps determine how much of the compound can dissolve in a given solvent under specific conditions.

What is KSP?

The solubility product constant (KSP) is an equilibrium constant that expresses the solubility of a sparingly soluble electrolyte. It represents the product of the concentrations of the constituent ions raised to the power of their stoichiometric coefficients at equilibrium.

For a general reaction:

AB(s) ⇌ A⁺(aq) + B⁻(aq)

The solubility product constant is defined as:

KSP = [A⁺][B⁻]

Where [A⁺] and [B⁻] are the equilibrium concentrations of the ions in solution.

How to Calculate KSP

To calculate KSP for silver bromide, you need to know the molar solubility of the compound. The molar solubility (s) is the number of moles of the solute that dissolve in one liter of solution.

For silver bromide, which dissociates completely in water:

AgBr(s) ⇌ Ag⁺(aq) + Br⁻(aq)

The solubility product constant is calculated as:

KSP = [Ag⁺][Br⁻] = s × s = s²

Where s is the molar solubility of AgBr in moles per liter.

KSP for Silver Bromide

The solubility product constant for silver bromide at 25°C is approximately 5.0 × 10⁻¹³. This value indicates that silver bromide is very insoluble in water.

Using the formula KSP = s², we can find the molar solubility of AgBr:

s = √KSP = √(5.0 × 10⁻¹³) ≈ 7.1 × 10⁻⁷ M

This means that only about 7.1 × 10⁻⁷ moles of AgBr will dissolve in one liter of water at 25°C.

Interpretation

A low KSP value like that of silver bromide indicates that the compound is highly insoluble. This property makes silver bromide useful in photographic applications, where it forms the basis for silver halide emulsions.

Understanding KSP helps predict the behavior of sparingly soluble salts in solution and is essential for designing experiments and industrial processes involving such compounds.

FAQ

What is the KSP for silver bromide?

The KSP for silver bromide at 25°C is approximately 5.0 × 10⁻¹³.

How is KSP calculated?

KSP is calculated as the product of the equilibrium concentrations of the constituent ions, raised to the power of their stoichiometric coefficients.

Why is silver bromide insoluble?

Silver bromide has a very low KSP value, indicating it is highly insoluble in water.

What is the molar solubility of silver bromide?

The molar solubility of silver bromide is approximately 7.1 × 10⁻⁷ M at 25°C.