Solute and solvent

solute is a substance that dissolves in a solvent with which it forms a solution. The solute is normally a solid, but it can also be a liquid or a gas. It is found in a lower proportion than the solvent in a solution.

solvent is the substance that dissolves a solute , forming a solution. This is normally a liquid, but it can also be a solid or a gas. It is found in greater proportion than the solute in a solution.

An example of a solution can be seen in a cup of coffee, in which the solute is ground coffee (solid) and the solvent is hot water (liquid).

SoluteSolvent
DefinitionIt is a substance that dissolves in a solvent and with which it forms a solution.It is a substance that dissolves a solute and with which it forms a solution.
Characteristics
  • Its most common state is solid, but it can also be gaseous and liquid.
  • It is the substance that is found in the least amount in the solution.
  • The amount of solute in a solution determines whether it is dilute, concentrated, saturated, or supersaturated.
  • It is generally a liquid, although it can be gaseous or solid.
  • It is found in greater proportion in a solution.
Solubility
  • When it is in the gaseous state, its solubility is affected by pressure, volume and temperature.
  • Polar solutes dissolve in polar solvents and nonpolar solutes dissolve in nonpolar solvents.
  • The size of the solute molecules determines the ease (speed) with which the solvent will be able to dissolve it.
  • Polar solvents dissolve in polar solutes and non-polar solvents dissolve non-polar solutes.
Colligative properties in a solution
  • The more particles a solute has, the higher the boiling point of the solution and the lower the melting point.
  • The amount of solute present in two solutions separated by a semi-permeable membrane has an effect on the phenomenon of osmosis.
  • The boiling point of a solvent is lower than that of the solution.
  • The melting point of a solvent is higher than that of the solution.
  • The vapor pressure of a solvent is greater than that of the solution.
Examples
  • In a cup of coffee, the solute is ground coffee.
  • In a dental amalgam, the solute is mercury.
  • In a cup of coffee, the solvent is water.
  • In a dental amalgam, the solvent is silver.

What is a solute?

solute is a substance that dissolves in a solvent with which it forms a solution. The proportion in which the solute is in the solution is less than the proportion of the solvent in which it dissolves.

The solute particles interact with those of the solvent, and the strength of this interaction between the solute and the solvent is greater than that holding the internal solute particles together. Basically, the solute molecules are stabilized by interacting with the solvent molecules.

Characteristics of a solute

  • It is the substance that is found in the least amount in the solution.
  • The most common state in which it occurs is solid, although there are also solutes in gaseous and liquid states.
  • When it is in the gaseous state, its solubility is affected by pressure, volume and temperature.
  • Polar solutes dissolve in polar solvents and nonpolar solutes dissolve in nonpolar solvents.

What is a solvent?

solvent is the substance in which a solute dissolves , forming a solution. The amount of solvent found in a solution is greater than the amount of solute found in it.

Water is the most common solvent. It is known as a “universal solvent” because it has a high dielectric constant. Substances in liquid, gaseous or solid states can dissolve in water.

Characteristics of a solvent

  • It is found in greater proportion in a solution.
  • Determine what the state of the solution will be.
  • It is generally a liquid, although it can be gaseous or solid.
  • Polar solvents dissolve polar solutes and non-polar solvents dissolve non-polar solutes.

Solvent polarity

Polar solvents have a high dielectric constant and have at least one electronegatively charged atom.

There are two types of polar solvents. On the one hand, there are the protic polar solvents . These solvents form hydrogen bonds, through OH or NH hydrogen bonds with those substances that they dissolve.

On the other hand, there are aprotic polar solvents , which are not capable of forming these hydrogen bonds. For example acetone is a polar aprotic solvent.

The apolar solvents are those with no negative or positive polarity, their atomic bonds have similar electronegative charges and produce no electric charge. These are mostly organic substances. For example, chloroform and hexane are nonpolar organic solvents.

What is a solution?

solution is a homogeneous mixture composed of at least two substances: a solute and a solvent .

Inside the solution, the solute is in a smaller proportion than the solvent.

Characteristics of a solution

  • A solution is a homogeneous mixture, which means that the substances that compose it are conjugated in such a way that it is not possible to differentiate them.
  • It is not possible to separate the substances that compose it again. Once mixed, both the solute and the solvent cannot be separated, at least by mechanical means (using a tool, filter, etc.).
  • It will remain stable without the need for any action to be taken on it, as long as the same conditions (temperature, pressure) are maintained.

Know the Difference between homogeneous mixture and heterogeneous mixture .

Solvation of a solution

The molecules of the solute and the solvent interact when they come into contact. The solvation is the process in which ions of the solute molecules yield to the solvent . When the solvation process occurs, the solvent molecules surround the solute molecules and they stop interacting with each other with the same force to do so with those of the solvent.

In this case, apply the principle that similar dissolves similar. This means that polar solute molecules only interact with polar solvents, and non-polar solutes only interact with non-polar solvents.

Solubility of a solution

If one substance is capable of dissolving in another, this substance is said to be soluble. The solubility of a solute is the maximum point at which it can no longer dissolve in a solvent.

This is the property of a substance that allows it to dissolve in another substance. When this happens, both substances reach an equilibrium, without the resulting solution presenting alterations, as long as the existing conditions are maintained.

Saturation of a solution

The solute reaches its solubility limit when it is no longer able to dissolve in the solvent. This is known as saturation . When more solute is added to a saturated solution, it will remain in the state it is in and will not dissolve, causing a supersaturation of the solution. On the other hand, an unsaturated solution is one in which the amount of solute to dissolve in the solvent is less than the maximum possible amount that could be dissolved.

Factors that affect the solubility of a substance

The temperature affects a substance according to the state where this is located. However, as a general rule, the higher the temperature, the more soluble a solvent will be.

  • When it comes to a solid solute, its solubility increases with increasing temperature in liquid solvents.
  • When it comes to a gaseous solute, its solubility decreases with increasing temperature in other gases and in liquids.
  • When dealing with a liquid solute with a liquid solvent, the effects of temperature depend on the particular case.

Another factor that affects solubility is polarity . The molecules that make up a substance are polar when they have an electropositive and electronegative charge at their ends (poles). If the molecule has no electrical charge, this molecule is nonpolar. Polar solutes dissolve in polar solvents, and nonpolar solutes dissolve in nonpolar solvents (so “similar dissolve similar”).

The pressure also affects the solubility, but does so particularly in the case of gases. Both solids and liquids do not undergo great changes in their soluble properties under greater or lesser pressure. Gases, on the other hand, when they undergo higher pressure are more soluble. According to Henry’s Law, postulated by William Henry (1774-1836), it states that “the solubility of a gas in a liquid is directly proportional to the pressure of the gas on the surface of the solution.”

The size (or volume) of the solute molecules is a factor that affects the rate at which it dissolves. In a solid, the size of the exposed area of ​​the solute determines how easily the solvent molecules will surround it.

Colligative properties of a solution

The colligative properties of a solution are those that depend only on the ratio between the amount of solute particles and those of the solvent, regardless of the composition of said substances. These properties are:

  • The boiling point of a solution is higher than that of its solvent (boiling point).
  • The melting point of a solution is lower than that of its solvent (cryoscopic descent).
  • The more particles a solute has, the higher the boiling point of the solution and the lower the melting point.
  • The vapor pressure of a solution is less than that of its solvent.
  • The phenomenon of osmosis: it occurs when the molecules of a liquid solvent (water) pass through a semi-permeable membrane between two solutions with different concentrations of a solute. The solution that has the largest amount of the solute receives the solvent from the other solution, until reaching an equilibrium between the two.

Classification of a solution according to the amount of solute

When the amount of solute in a solution is low, it dissolves in the solvent easily, and the solution is considered dilute. On the other hand, when there is a large amount of solute and it dissolves with difficulty, the solution is concentrated. In the event that the solute is no longer able to dissolve in the solvent, the solution is said to be saturated.

Examples of solutions

  • Glues
  • Paintings.
  • Medicines.
  • Herbal infusions (tea).
  • Coffee (prepared as a drink).
  • Soaps
  • Alloys between metals.
  • The air.

Types of solutions

StateExamples
Gaseous solvent + gaseous soluteOxygen + acetylene = oxyacetylene mixture (used in metal welding)
Gaseous solvent + liquid soluteAir + water = humid air or water vapor.
Gaseous solvent + solid soluteAir + dust and smoke = smog
Liquid solvent + gaseous soluteWater + carbon dioxide = carbonated water
Liquid solvent + liquid soluteWater + acetic acid = vinegar
Liquid solvent + solid soluteWater + salt = salt water
Solid solvent + gaseous solutePlatinum + hydrogen = hydrogen electrode
Solid solvent + liquid soluteGold + mercury = gold amalgam
Solid solvent + solid soluteCopper + tin = bronze

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