10 Solubility Examples

The solubility is the ability of a substance (solute) to dissolve in a given medium (solvent). For example: salt in water, coffee with milk, atmospheric gases.

The term is also used to designate the maximum amount of a solute that a solvent can dissolve under given conditions of temperature and pressure. Pressure influences solubility much more if the solute is a gas. Solubility can be used to refer to ways of expressing the concentration of solutions such as molarity, molality, among others.

Solubility is not a universal characteristic of all substances, so some dissolve better in others and some simply do not dissolve in others. The water, often referred to as the universal solvent, it cannot completely dissolve the oil, for example. However, by altering the temperature and / or pressure at which a mixture occurs or by adding other specific substances, it is possible to vary the solubility of certain solutes in certain solvents.

Between the factors That affect solubility, there is also the nature or polarity of the solute and solvent. In this sense, polar substances dissolve well in polar substances, while nonpolar ones are very soluble in nonpolar ones. Polar substances are not soluble in apolar substances and vice versa, although there is always a certain range of polarities in which both substances can still be dissolved. The molecular explanation for this is due to the different intermolecular attractive forces determined by polarity. Thus the phrase arises: “similar dissolves similar.”

Finally, once the solvent cannot dissolve any more solute, the solution is said to be saturated; but if the specific conditions are obtained, especially temperature, it is possible to further increase the solubility until a solution is obtained. oversaturated. On the other hand, if the solvent can continue to dissolve solute before it becomes saturated, the solution is said to be unsaturated.

Examples of solubility

  1. Salt (sodium chloride) in water. Common salt is ordinarily dissolved in water, according to a rate of 360 g / l, as long as the water is at 20 ºC. This indicates that 360 grams of salt can be dissolved in one liter of water at this temperature. If we increase the temperature of the water, the amount of salt will increase.
  2. Fizzy drinks. Canned or bottled sodas have a high amount of carbon dioxide (COtwo) dissolved inside which gives them their characteristic bubbling. This occurs by supersaturating the mixture under very high pressure conditions. Contrary to the previous example, increasing the temperature of this mixture destabilizes it and releases more gases, thereby reducing the solubility rate.
  3. Solutions with iodine. Many solutions that use iodine (such as those used to heal superficial wounds) cannot use water in their preparation since iodine is not soluble in water. On the other hand, by using alcohol, the solubility rate is improved and the mixture can be produced.
  4. Coffee with milk. Taking as an example coffee with milk (in which milk is added to coffee), we will see that the solubility rate of milk in coffee increases if we increase the temperature.
  5. Oxygen in the blood. The oxygen in the air that we require to live is a gas. Even so, this element is transported in our blood to the various tissues that require it, and this is carried out through a solution, allowed by biomolecules such as hemoglobin. People with a greater presence of this compound in the blood may have more oxygenated tissues.
  6. Dissolve ethanol in benzene and in water. Even though benzene is apolar and water is polar, ethanol can dissolve in both. This is because it has hydrocarbon parts that make it similar to benzene (an aromatic hydrocarbon) and, at the same time, because it has a hydroxyl group (-OH) that can establish hydrogen bonds with water.
  7. Atmospheric gases. Many gases that we daily release into the atmosphere are not soluble in air, and they often displace air and take its place. However, as they rise in the atmosphere and the pressure to which they are subjected varies, this condition varies and mixing is finally produced, which is sometimes an important source of environmental pollution (such as the destruction of the ozone layer).
  8. Oil paint and thinner (thinner). Oil paint thinners are organic solvents derived from petroleum, whose hydrocarbon composition allows dissolving the layers of enamel, oil or grease paint, which are similar in composition and polarity.
  9. Nitrates (NO3-) in water. All substances formed by nitrates (compounds that contain molecular groups of nitrogen and oxygen) are perfectly soluble in water. This is verifiable in the processes of water pollution by the chemical industry or agro-fertilizers whose waste (rich in nitrogen) reaches the sea and rivers and there they dissolve easily and deteriorate the quality of life.
  10. Acetone dissolved in water. Short-chain ketones are soluble in water, but as the carbon chain increases, their solubility decreases. Acetone or propanone (CH3Car3) is a ketone with three carbon atoms and is soluble in water.