용해도(Solubility)는 용질(Solute)이 용매(Solvent)에 얼마나 용해되는지를 결정하는 일련의 규칙에 의해 기능하며, 용질과 용매의 물리적, 화학적 특성에 전적으로 의존합니다. 즉, 용질은 전형적으로 가장 분자적 유사성을 갖는 용매에서 가장 잘 용해됩니다: 극성 용질 (Polar Solutes)은 극성 용매(Polar Solvents)에 더 잘 용해되고, 비극성 용질(Nonpolar Solutes)은 비극성 용매(nonpolar solvents)에서 더 잘 용해됩니다. 또한, 용질 내의 분자가 용매 내의 분자보다 작으면 용질은 더욱 잘 용해 될 것입니다. 이는 용매 분자가 더 큰 분자를 둘러싸는 것이 더 어렵기 때문입니다. 온도 또한 용해도에 영향을 미치며, 일반적으로 용해도는 열과 함께 증가하지만, 기체의 경우에는 용해도가 감소할 수도 있습니다. 압력 역시 기체의 용해도에 영향을 미치는 핵심적인 요소입니다. Stirring 또는 Sonication 처리는 종종 용해 속도를 증가시키는데 필요하지만, 물질의 용해도에는 영향을 주지 않습니다. 용해도는 물질이 얼마나 빨리 용해되는지와는 무관하므로, 용해도에 대한 결정에서 속도를 고려해서는 안 됩니다.
Cayman provides solubility data for most of our 20,000 biochemical compounds on each product page to help guide you in choosing a solvent.
Solubility Rules Chart
아래 표(이미지)에 있는 Cations(상단 행)과 Anions(첫 번째 열)을 교차하여 만들어진 화합물의 조성식(Empirical Formula)을 사용하여 Solubility를 결정할 수 있습니다. (표는 PDF로 다운로드 가능합니다)
흔하지 않은 화합물의 경우, Cayman Chemical에서 안내하는 “Solubility Guideline”과 주기율표를 참고할 수 있겠습니다.
Solubility Guidelines*
*Pertains to substances in water at room temperature and standard pressure.
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Salts containing Group I elements (Li+, Na+, K+, Cs+, Rb+) or ammonium ions (NH4+) are soluble.
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Salts containing nitrates (NO3–), acetates (C2H3O2–), chlorates (ClO3–), and perchlorates (ClO4–) are generally soluble.
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Binary compounds of halogens (Cl–, Br–, or I–) with metals are generally soluble. Exceptions to this include halide salts of fluoride (F–), silver (Ag+), lead (Pb2+), and mercury (Hg2+). Lead halides are, however, soluble in hot water. Most silver salts are insoluble except for AgNO3 and Ag(C2H3O2).
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Most sulfate salts (SO42-) are soluble. Exceptions to this include CaSO4, BaSO4, Ag2SO4, HgSO4, and SrSO4, which are slightly soluble. PbSO4 is poorly soluble.
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Most hydroxide salts (OH–) are insoluble. Exceptions include hydroxide salts of Group I elements, transition metals, aluminum, and ammonium. Hydroxide salts of Group II elements (Ca2+, Sr2+, and Ba2+) are only slightly soluble.
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Most sulfides (S2-) of transition metals are highly insoluble, including CdS, FeS, ZnS, and Ag2S. Arsenic, antimony, bismuth, and lead sulfides are also insoluble. However, calcium (Ca2+), barium (Ba2+), strontium (Sr2+), magnesium (Mg2+), sodium (Na+), potassium (K+), and ammonium (NH4+) sulfides are soluble.
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Carbonates (CO32-), oxalates (C2O42-), chromates (CrO42-), phosphates (PO42-), and fluorides (F–) are frequently insoluble. Although, compounds containing Group I elements or ammonium are soluble, except for lithium phosphate, which is poorly soluble.
Frequently Asked Questions about Solubility
A: Cayman’s Product Information sheets provide solubility data for most compounds using common polar and non-polar solvents. Solvents such as water (protic), PBS (protic), ethanol (protic), DMSO (aprotic), and dimethyl formamide (DMF) (aprotic) are commonly listed. Your specific application may require the use of a solvent that is not listed, and the compatibility of that solvent with your compound may not be known. The choice of appropriate solvent will depend on the polarity of the solvent and polarity of your compound (solute).
A solvent polarity scale derived from Reichardt’s dye, representing solvent polarity in correlation with chemical kinetics and equilibria (Sherwood, J. Bio-based solvents for organic synthesis, 2014).
Other factors such as size and crystal structure of your solute may also affect solubility. You may need to heat, stir, or even sonicate your solution for complete dissolution. Be aware that compounds in solution may become unstable. It is best practice to make fresh solutions for your experiments or store pre-made solutions at -80°C.
A: If the target concentration is within the solubility limit listed on the Product Information sheet, gentle warming and gentle mixing may help dissolve the compound. Rapid temperature changes and harsh mixing may compromise the integrity of the chemical. Some chemicals are temperature sensitive and/or sensitive to oxidation. It is not uncommon for a compound to misbehave and not go into solution even at published concentrations. See “I found different solubility data from different sources. Which one is right?”
A: There can be variations in solubility for the same chemical from different vendors or different batches from the same vendor. The following factors can affect the solubility of the same chemical: solvent of crystallization, residual solvent content, polymorphism, salt versus free form, degree of hydration, solvent temperature, and dissolved oxygen.
