dissolution equilibrium can act on the compound application. Dissolved solids may be covalent compounds (organic compounds: sugars and inorganic compounds: hydrogen chloride) or an ionic compound (e.g., salt, i.e. sodium chloride), when the main difference between them will ionizing ionic compound is dissolved in water ion (covalently compounds may also, such as acetic acid, hydrogen chloride, nitrate, lead acetate). Water is the most commonly used solvents, but the same principles apply to any solvent. Concentration
in environmental science, all dissolved in water solid material (whether or not saturated) is referred to as total dissolved solids (TDS).
dissolved organic solids balance is a balance between its solid portion and the soluble fraction:
This expression was dissolved upon reaching said equilibrium concentration of dissolved sugars contained in the water is equal to K. At 25 ℃, when the standard concentration of 1mol / L, sucrose K = 1.971, which is capable of dissolving at 25 ℃ sucrose maximum amount, then the solution is called "saturated." If the current is below the saturation concentration of the solution concentration, the solid will continue until the two are equal or dissolve all solids have been dissolved; if the current concentration of the solution above the saturation concentration of the solution at this time is "supersaturated" will sucrose solution as a solid precipitate, until the two are equal. This process can be slow, but equilibrium constant is described equilibrium state of the system, not the speed of the system to reach equilibrium.
ionizing ionic compound usually occurs at the time of dissolution, i.e., dissociate into ions under the action of water. Such as calcium sulfate:
this expression describes the aqueous solution of calcium sulfate equilibrium product concentration of both ions by the ionized calcium sulfate equal to K sp , of the instant product. Solubility product of calcium sulfate was 4.93 × 10 -5 . If the solution containing calcium sulfate only, i.e. only by containing ionized Ca and SO 4 , then the concentration of each ion is:
when the counting number one solute ionization unequal parts:
and solubility of the solubility product is determined by the following equation:
The above equation is assumed that the ionization process occurs in a pure solvent (no occurrence of common ion effect), nor the presence of complexing and hydrolysis (i.e., present in the solution only B and C), and the concentration of the ion activity can be small It is considered equal to 1.
ion effect refers to a mobile equilibrium dissolution occurred based on Le Chatelier's Principle. In the above example, is added as a sulfate ion (i.e., addition of soluble sulfates, such as sodium sulfate, etc.) to a saturated solution of calcium sulfate will cause the calcium sulfate precipitation, ion concentration until product solubility product meet up again.
means that the salt effect of other salts present in the solution, even without the same ion, also affect the ionic strength, thereby affecting the ion activity. Therefore, even if K sp kept constant, the solubility is also changed (still the default activity is a solid).