Solubility product
Introduced| English | Meaning |
|---|---|
| solubility product/ˌsɒljuːˈbɪlɪti ˈprɒdʌkt/ | The equilibrium constant for dissolution of a sparingly soluble ionic solid, expressed using the activities of its dissolved ions. |
| saturated/ˈsætʃəreɪtɪd/ | Describing a solution unable to dissolve more solute under stated conditions, or an organic molecule with no carbon-carbon double or triple bonds. |
| solubility/ˌsɒljuːˈbɪlɪti/ | The maximum amount of a solute that can dissolve in a specified amount of solvent at a given temperature and pressure. |
| common ion effect/ˈkɒmən ˈaɪɒn ɪˈfekt/ | common ion effect |
How much will dissolve?
- For a salt that barely dissolves, the solubility product 溶度积 $K_{\text{sp}}$ describes its saturated 饱和 solution.
- It links solubility 溶解度 to the ion concentrations.
- A common ion makes the salt less soluble.
Solubility product lab
ionic product compared with Ksp
Increase ion concentration and see when precipitation becomes likely.
The equilibrium constant for a sparingly soluble salt dissolving is the solubility ______.
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Written Ksp.
The solubility product
- $K_{\text{sp}}$ is the product of the ion concentrations, each raised to the power of its number in the formula:
$$K_{\text{sp}} = [\text{Ag}^+][\text{Cl}^-] \qquad K_{\text{sp}} = [\text{Ca}^{2+}][\text{F}^-]^2$$
- You can find $K_{\text{sp}}$ from the solubility, or the solubility from $K_{\text{sp}}$.
Stalactites form as dissolved minerals come back out of solution — there is a limit to how much will dissolve
The solubility product Ksp is:
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For a saturated solution, Ksp multiplies the ion concentrations (each to the power of its formula coefficient).
For CaF₂, the solubility product is:
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There are two F⁻ per formula unit, so the [F⁻] term is squared.
Match each solubility-product idea.
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Each item links the term to its correct meaning.
The common ion effect 同离子效应
- A salt is less soluble in a solution that already contains one of its ions.
- The extra ion pushes the dissolving equilibrium back (Le Chatelier), so less salt dissolves.
- You can calculate the new solubility using $K_{\text{sp}}$ and the common ion's concentration.
The common ion effect means a salt becomes:
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The extra (common) ion pushes the dissolving equilibrium back, so less salt dissolves.
The common ion effect is explained by:
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Adding a common ion shifts the dissolving equilibrium towards the solid, reducing solubility.
The common-ion effect
- Adding an ion already in the equilibrium lowers the solubility of a sparingly soluble salt.
- Ksp must still be satisfied, so less salt dissolves.
You've got it
- $K_{\text{sp}}$ = product of ion concentrations, each to the power of its formula number (e.g. $K_{\text{sp}} = [\text{Ca}^{2+}][\text{F}^-]^2$)
- find $K_{\text{sp}}$ from solubility, or solubility from $K_{\text{sp}}$
- the common ion effect: a salt is less soluble when a common ion is present (Le Chatelier)