solubility

Examples of solubility in the following topics:

• Solubility

  • The degree of solubility ranges widely depending on the substances, from infinitely soluble (fully miscible), such as ethanol in water, to poorly soluble, such as silver chloride in water.
  • The solubility of gases displays the opposite relationship with temperature; that is, as temperature increases, gas solubility tends to decrease.
  • In contrast, a non-polar solute such as naphthalene is insoluble in water, moderately soluble in methanol, and highly soluble in benzene.
  • The solubility chart shows the solubility of many salts.
  • The solubilities of salts formed from cations on the left and anions on the top are designated as: soluble (S), insoluble (I), or slightly soluble (sS).

• Solid Solubility and Temperature

  • Solubility often depends on temperature; the solubility of many substances increases with increasing temperature.
  • The solubility of a given solute in a given solvent typically depends on temperature.
  • Many salts show a large increase in solubility with temperature.
  • Some solutes exhibit solubility that is fairly independent of temperature.
  • A useful application of solubility is recrystallizaton.

• Gas Solubility and Temperature

  • Solubility of a gas in water tends to decrease with increasing temperature, and solubility of a gas in an organic solvent tends to increase with increasing temperature.
  • Several factors affect the solubility of gases: one of these factors is temperature.
  • The trend that gas solubility decreases with increasing temperature does not hold in all cases.
  • There are several molecular reasons for the change in solubility of gases with increasing temperature, which is why there is no one trend independent of gas and solvent for whether gases will become more or less soluble with increasing temperature.
  • Methane, oxygen, carbon monoxide, nitrogen, and helium all have different solubilities in water, but all of them become less soluble with increasing temperature.

• Molar Solubility and Relative Solubility

  • The relation between the molar solubility and the solubility product means that one can be used to find the other.
  • What is the molar solubility?
  • Compare their molar solubilities in water at 25 °C.
  • If compounds have different solubilities, or relative solubilities, they can be separated.
  • Calculate the molar solubility of a compound in water and the relative molar solubility of compounds

• Solubility Product

  • At a certain temperature, the solubility of Fe(OH)2 in water is 7.7 x 10-6 mol/L (M).
  • Solubility products are useful in predicting whether a precipitate will form under specified conditions.
  • The solubility product of a number of substances have been experimentally determined and can be used to predict solubility at a specified temperature.
  • The solubility of Fe(OH)2 is 7.7 x 10-6 M, this is equal to the value of the change (x) in the table.
  • The solubility product constants of a number of substances.

• Lipid Soluble Vitamins

  • The essential dietary substances called vitamins are commonly classified as "water soluble" or "fat soluble".
  • Water soluble vitamins, such as vitamin C, are rapidly eliminated from the body and their dietary levels need to be relatively high.
  • The lipid soluble vitamins, shown in the diagram below, are not as easily eliminated and may accumulate to toxic levels if consumed in large quantity.
  • From the structures shown here, it should be clear that these compounds have more than a solubility connection with lipids.

• Effect of a Common Ion on Solubility

  • Adding a common ion decreases the solubility of a solute, causing it to precipitate.
  • With such a small solubility product for CaF2, you can predict its solubility << 0.10 moles per liter.
  • If our prediction is valid, we can simplify the solubility-product equation:
  • Lithium hydroxide forms less-soluble lithium carbonate, which precipitates because of the common ion effect.
  • Calculate the molar solubility of a compound in solution containing a common ion.

• Water Solubility

  • Water has been referred to as the "universal solvent", and its widespread distribution on this planet and essential role in life make it the benchmark for discussions of solubility.
  • Organic compounds that are water soluble, such as most of those listed in the above table, generally have hydrogen bond acceptor and donor groups.
  • The least soluble of the listed compounds is diethyl ether, which can serve only as a hydrogen bond acceptor and is 75% hydrocarbon in nature.
  • Even so, diethyl ether is about two hundred times more soluble in water than is pentane.
  • The chief characteristic of water that influences these solubilities is the extensive hydrogen bonded association of its molecules with each other.

• Solubility and Pressure

  • Increasing pressure will increase the solubility of a gas in a solvent.
  • However, the solubility of gases shows significant variability based on pressure.
  • Typically, a gas will increase in solubility with an increase in pressure.
  • When a gas is dissolved in a liquid, pressure has an important effect on the solubility.
  • Recognize the relationship between pressure and the solubility of a gas

• Precipitation Reactions

  • Lastly, to make predictions about precipitation reactions, it is important to remember solubility rules.
  • The following solubility chart gives a useful summary:
  • To determine the solubility of an given salt, find the cationic component along the left-hand side, match it to the anionic component along the top, then check to see if it is S - soluble, I - insoluble, or sS - slightly soluble.
  • Distinguish ways to write precipitation reactions (complete ionic equation and net ionic equation) and use a solubility table to determine whether a precipitation reaction will occur