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What is the Ksp of copper bromide?

Published in Solubility Product Constant 3 mins read

The Ksp of copper(I) bromide (CuBr) is 6.3 × 10⁻⁹.

Understanding Copper Bromide

The term "copper bromide" can refer to different chemical compounds depending on the oxidation state of the copper atom. The most common forms are:

  • Copper(I) bromide (CuBr): Also known as cuprous bromide, where copper has a +1 oxidation state.
  • Copper(II) bromide (CuBr₂): Also known as cupric bromide, where copper has a +2 oxidation state.

The solubility product constant (Ksp) is a measure specifically used for sparingly soluble ionic compounds. Copper(I) bromide (CuBr) is a sparingly soluble salt, which is why its Ksp value is widely reported and relevant for understanding its behavior in solution. Copper(II) bromide (CuBr₂) is generally considered soluble.

The Solubility Product Constant (Ksp)

The Ksp is an equilibrium constant that describes the extent to which an ionic compound dissolves in water. For a generic sparingly soluble ionic compound, MₓAᵧ, dissolving in water:

MₓAᵧ(s) ⇌ xMʸ⁺(aq) + yAˣ⁻(aq)

The Ksp expression is given by:

Ksp = [Mʸ⁺]ˣ[Aˣ⁻]ʸ

A smaller Ksp value indicates lower solubility, meaning less of the compound will dissolve in water to form ions. Conversely, a larger Ksp value suggests higher solubility.

Ksp Value for Copper(I) Bromide

The Ksp value for copper(I) bromide (CuBr) is a critical indicator of its limited solubility in aqueous solutions.

Compound Chemical Formula Ksp Value
Copper(I) Bromide CuBr 6.3 × 10⁻⁹

What This Ksp Value Means

A Ksp value of 6.3 × 10⁻⁹ for copper(I) bromide is a very small number. This signifies that CuBr has low solubility in water. When CuBr is added to water, only a tiny fraction of it will dissolve to produce Cu⁺ and Br⁻ ions. The majority of the compound will remain in its solid, undissolved form.

For example, in a saturated solution of CuBr, the concentration of copper(I) ions and bromide ions would be relatively low, reflecting this limited solubility.

Applications and Importance of Ksp

Understanding Ksp values is fundamental in various chemical and industrial applications:

  • Predicting Precipitation: Ksp helps determine if a precipitate will form when two solutions containing potential precipitating ions are mixed. If the ion product (Qsp) exceeds the Ksp, precipitation will occur.
  • Calculating Solubility: Ksp values can be used to calculate the molar solubility of a sparingly soluble salt, which is the concentration of the dissolved salt in a saturated solution.
  • Common Ion Effect: Ksp is essential for understanding how the solubility of a sparingly soluble salt decreases when a common ion (an ion already present in the solution) is added.
  • Analytical Chemistry: It plays a role in qualitative analysis, separating ions by selective precipitation.
  • Environmental Science: Ksp is relevant in understanding the transport and fate of pollutants in water systems, especially for metal ions.