Solubility is a kind of substance when forming solutionphysical property。It means that the substance is in a specific solventSolubilityAn attribute of size.
solubilityIt means that the solution that reaches (chemical) equilibrium cannot contain more solutes, and it means the maximum extent of substance dissolution in a specific solvent.Under special conditions, there will be more solutes dissolved in the solution than normal, and then it will becomeSupersaturated solution。The amount of solute that can be dissolved by each (usually the mass of each) solvent (sometimes a solution)MaximumIt is "solubility of solute in this solvent".
Definition: ReachEquilibriumThe solution of can't contain more solutes (of course, other solutes can still be dissolved), we call itSaturated solution。If the solvent is not specified, it usually means that the solvent is water, such as“sodium chloride"And" solubility of sodium chloride in water "can be considered to have the same meaning.Solubility is not a constant value.The solubility of a solute in solvent is determined by itsIntermolecular force, temperature, the change of entropy in the process of dissolution, and the existence of other substances[1]Sometimes it is also related to the pressure or partial pressure of gas solute.Therefore, the solubility of a substance should preferably be expressed as: "At 20 degrees, the solubility of a substance in 100 grams of water is xxxx under standard pressure." If not specified, the temperature and pressure usually refer toStandard status(STP)
SolubilityIt refers to the degree to which a substance can be dissolved.The substance that dissolves is called solute, and the liquid (usually excessive) that dissolves other substances is called solvent, orDispersantThe resulting mixture is called solution.
Definition of solubility: at a certain temperature, a solid substance reachesSaturation stateThe mass dissolved at.
If a solute can be well dissolved in the solvent, we say that the substance issoluble Of.If the degree of dissolution is not large, the substance is calledSlightly solubleOf.If it is difficult to dissolve, it is calledInsolubleorInsolubleOf.
In fact, the solubility often depends on thedissolutionequilibrium constant。This is one of the equilibrium constants, reflecting the dissolution of solute-Precipitation equilibriumOf course, it can also be used in the precipitation process (at that time, it was calledSolubility product）。Therefore, solubility has a great relationship with temperature, which is not difficult to explain.
achievechemical equilibriumThe solution of can't contain more solutes (of course, other solutes can still be dissolved), we call itSaturated solution。Under special conditions, there will be more solutes dissolved in the solution than normal, and then it will becomeSupersaturated solution。
About solvents
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solventIt is generally divided into two categories: polar solventsNon-polar solvent。The relationship between solvent types and solubility of substances can be summarized as: "dissolve what it is like".It means that,Polar solventAble to dissolveIonic compoundAnd candissociationOfCovalent compoundNon polar solvents can only dissolve non-polar covalent compounds.stayOrganic chemistryThe solvents commonly used inacetone、ethanol, water.
Water and non-polar solvents cannotmutually dissolvableIf you have to do this, they will not form a uniform mixture and will eventually separate into two layers, which is calledSuspension, or add corresponding additives (commonly used in pesticides) to the oil,Water ingressPost formationOil in waterorWater in oilA homogeneous emulsion of.
Application of solubility
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① It means that the substance is in the solventSolubilitySize of.
② Solubility isphysical propertyMost dissolution is a physical change (some dissolution is a chemical change, such assodaDissolved in acidchemical reaction）。
③ Solubility is determined bysolubilityDetermined.(solid)
Solubility judgment table
Solubility
20 ℃ solubility
remarks
Insoluble or insoluble
-
-
Slightly soluble
0.01～1g
soluble
1g～10g
Soluble
>10g
④ The following applications can be achieved by using solubility:
a、Judge gas collection method
Soluble（Soluble）Gas in water cannot be extracted by drainage method
E.g. COtwo
And Htwo，OtwoDue to poor solubility, drainage and gas extraction method can be used.
When the solubility of two substances in water is obviously different, they can be usedFiltration methodSeparation.
For example: KNOthree(Soluble) and CaCOthree(Insoluble）It can be separated by filtration;
C and MnOtwoBoth are insolubleNaCl、KNOthreeBoth are soluble and cannot be separated by filtration.
Solubility algorithm: solute mass/solvent mass (usually water)
Unit: g/100g water
Solubility table
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-
OH-
NOthree-
Cl-
SOfour2-
COthree2-
H+
HtwoO (not acid and alkali salts)
Dissolving and volatilizing (nitric acid)
Dissolve and volatilize (hydrochloric acid)
Soluble (sulfuric acid)
Dissolving and volatilizing (carbonic acid)
NHfour+
Dissolving and volatilizing (ammonia water, ammonium hydroxide)
dissolve
dissolve
dissolve
dissolve
K+
Dissolved (caustic potash)
dissolve
dissolve
dissolve
dissolve
Na+
Soluble (sodium hydroxide)
dissolve
dissolve
dissolve
dissolve
Ba2+
dissolve
dissolve
dissolve
no
no
Ca2+
Micro (hydrated lime)
dissolve
dissolve
tiny
no
Mg2+
no
dissolve
dissolve
dissolve
tiny
Al3+
no
dissolve
dissolve
dissolve
-
Mn2+
no
dissolve
dissolve
dissolve
no
Zn2+
no
dissolve
dissolve
dissolve
no
Fe2+
no
dissolve
dissolve
dissolve
no
Fe3+
no
dissolve
dissolve
dissolve
-
Cu2+
no
dissolve
dissolve
dissolve
-
Ag+
-
dissolve
no
tiny
no
Note: "Soluble" means that the substance is soluble in water, "non" means that it is insoluble in water, "micro" means that it is slightly soluble in water, and "volatile" means that it is slightly soluble in watervolatility, "-" means that the substance does not exist or decomposes when encountering water.
Soluble formula
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Soluble Formula I
① , potassium and sodiumammonium saltQuick dissolving water
