Unsaturated solution Saturated solution 30

Dissolution is when the solute molecules enter the space between the molecules of the solvent, and when the space is full, it can no longer be dissolved.

A saturated solution is formed.

There are gaps between the particles.

Other particles fill the gap (but not fill it).

When other things are equal.

The gap is filled as much as possible.

A saturated solution is formed.

The difference between saturated solution and unsaturated solution is that if the solute is added to the unsaturated solution, it will be converted into a saturated solution.

At a certain temperature, a certain solute is added to a certain amount of solvent, and when the solute can not continue to dissolve, the resulting solution is called the saturated solution of this solute; The solution that can continue to dissolve is called the unsaturated solution of this solute.

Solubility. For example, at room temperature, there is a maximum amount of sodium chloride that can be dissolved in 20 ml of water, which is the mass that can be dissolved when forming its saturated solution. This shows that at a certain temperature, there is a certain limit to the amount of solute dissolved in a certain amount of solvent.

Chemically, the limit of this dissolution is expressed in terms of solubility.

Solubility refers to the amount of solute in a saturated solution at a certain temperature and pressure. It is customary to call the quality of the solute dissolved when the saturated state of 100g of solvent is called the solubility of the solute in this solvent.

If no solvent is specified, solubility is usually referred to as the solubility of the substance in water. In chemistry, for the convenience of calculation, people also use the quantity concentration of the substance to express the solubility of the solute, that is, the amount of the substance dissolved when the saturated state of the solute in 1L solution is called the solubility of the substance in the solvent, and its unit is the same as the unit of the concentration of the substance, which is mol·l-1.

The above content participates: Encyclopedia - Saturated Solution.

1. Saturated solution refers to the fact that at a certain temperature, a certain dose of solvent cannot continue to dissolve the solute, which means that the concentration of the solution remains unchanged.

2. At a certain temperature, a solution of a certain solute can no longer be dissolved in a certain amount of solvent (that is, the solubility of the solute has been reached.

of the solution). A solution in which a solute can continue to dissolve at the same temperature (i.e., a solution that has not yet reached the solubility of the solute) is called an "unsaturated solution". If the solute is a gas, the pressure of the gas is also indicated.

An unsaturated solution is a solution that can dissolve a certain substance in a certain amount of solvent at a certain temperature. Saturated solution is a solution obtained by adding a certain solute to a certain amount of solvent at a certain temperature, and when the solute can no longer be dissolved.

In the case of increasing the solvent or increasing the temperature, the saturated solution can become an unsaturated solution. Therefore, only by specifying "in a certain amount of solvent" and "at a certain temperature" can the "saturated" and "unsaturated" of the solution have a definite meaning.

The process of the saturated solution and the unsaturated solution of a certain solute can be converted into each other as follows: the temperature of the calcium hydroxide solution is changed contrary to the general law when the calcium hydroxide solution is converted, and the solute in a certain substance can be dissolved.

It should be clarified that the saturated or unsaturated solution of "a certain substance", such as a solution that can no longer dissolve NaCl under certain conditions, may also dissolve sucrose, for sucrose, the solution is an unsaturated solution, so it must be indicated which solute saturated solution or unsaturated solution.

The solubility of solute gases in liquids is a quantitative representation of the equilibrium relationship between gas and liquid. At a certain temperature and pressure, when the absorbent comes into contact with the mixed gas, the absorbent in the gas is transferred to the liquid absorbent, so that its concentration in the absorbent increases and a solution is formed. After a period of contact, the solute concentration in the liquid phase no longer increases and reaches saturation, and the two phases reach phase equilibrium.

The above content reference: Encyclopedia - Unsaturated Solution.

Refer to the above content: Encyclopedia - Saturated Solution.

The concept of unsaturated solution is a solution that can dissolve a certain substance in a certain amount of solvent at a certain temperature. Specify a certain temperature and a certain amount of solvent, because changing the amount or temperature of the solvent, the saturated solution and the unsaturated solution can be converted into each other, and the unsaturated solution can be converted into a saturated solution by increasing the solute or decreasing the temperature and evaporating the solvent.

Properties of unsaturated solutions

An unsaturated solution at a certain temperature can be turned into a saturated solution by changing the temperature, etc., so as to crystallize, a necessary condition for crystallization.

It is a saturated solution. The above transformation conditions are suitable for most solid substances, because the maximum amount of most solid substances dissolved in a given amount of water increases with increasing temperature.

Hydrated lime. The maximum amount dissolved in a certain amount of water decreases with the increase of temperature, so if the unsaturated solution of hydrated lime is converted into a saturated solution, the temperature should be increased when the temperature is changed, and if the saturated solution is converted into an unsaturated solution, the method of reducing the temperature or increasing the solvent can be used.

When there is a residual solute at the bottom of the solution, and the amount of solute is no longer reduced, indicating that the solution is saturated, when there is no remaining solute at the bottom of the solution, a small amount of the solute can be added to the solution, after stirring, if it can be dissolved or a part of it can be dissolved, indicating that the solution is not saturated, if it cannot be dissolved, it indicates that the solution is saturated.

Unsaturated solution: At a specific temperature, in a certain amount of solvent, the solution that can dissolve a certain substance is called the unsaturated solution of this solute. Such as:

At room temperature, table saltSolubility. It is 36 grams, if 20 grams of salt is added to 100 grams of water, the salt is completely dissolved, but a certain amount of salt can also be dissolved, and the salt water at this time is called unsaturated solution.

Saturated solution:It is a certain solute that is added to a certain amount of solvent at a specific temperature, and when the solute can no longer be dissolved, the solution obtained is called a saturated solution of this solute. Such as:

At room temperature, the solubility of salt is 36 grams, if 36 grams of salt is added to 100 grams of water, the salt is just completely dissolved, if a certain amount of salt is added, it can no longer be dissolved, and the salt water at this time is called saturated solution.

Saturated and unsaturated solutions can be converted to each other:When the solvent is added to the saturated solution or the temperature is increased, then the saturated solution can become an unsaturated solution. Therefore, it is necessary to specify "in a certain amount of solvent" and "at a specific temperature" for the "saturated" and "unsaturated" of the solution to have a definite meaning.

The above content reference: Encyclopedia - Unsaturated Solution.

Unsaturated solution: A solution that can continue to dissolve a solute in a certain amount of solvent at a certain temperature.

When a solvent (usually a solid) is added to a solvent (usually a liquid), both processes occur simultaneously. Dissolution is the dissolution of solutes in a solvent and crystallization is the opposite process of reacting to deposit solutes. In unsaturated solutions, the dissolution rate is much greater than the crystallization rate.

Example of an unsaturated solution: Adding a spoonful of sugar to a cup of hot coffee creates an unsaturated sugar solution. Vinegar is an unsaturated solution of acetic acid in water.

A method for judging whether a solution is saturated

Observation: When there is a residual solute at the bottom of the solution, and the amount of solute is no longer decreasing, it indicates that the solution is saturated.

Experimental method: when there is no remaining solute at the bottom of the solution, a small amount of the solute can be added to the solution, and after stirring, if it can be dissolved or a part of it can be dissolved, indicating that the solution is not saturated; If it does not dissolve, the solution is saturated.

The above content reference: Encyclopedia - Unsaturated Solution.

Whether the solution is saturated or unsaturated, the most important thing is to see if it can dissolve more solutes, nor to see the concentration or light of the solution, the solubility of each substance is not the same, the solubility of the same substance at different temperatures is also different, some substances, such as calcium carbonate, the solubility is very small, even if it is a saturated solution of calcium carbonate, it still looks very light, calcium carbonate at 8 degrees Celsius, 100 grams of water can only dissolve grams at most. Contrary to calcium carbonate, some substances such as sucrose have a great dissolving capacity, even if the solution of sucrose is already very thick, but it is not a saturated solution of sucrose, sucrose at 20 degrees Celsius, 100 grams of water is considered to dissolve 200 grams of sucrose, but the sucrose solution at this time is still not a saturated solution, because it can also dissolve more sucrose.

The solubility of the substance is also affected by the temperature, for example, at 20 degrees Celsius, 100 grams of water can dissolve up to 203 grams of sucrose, but in 30 degrees Celsius water, 100 grams of water can dissolve sucrose. Therefore, the solution formed when dissolving 203 grams of sucrose in 100 grams of water is a saturated solution of sucrose at 20 degrees Celsius, but it is an unsaturated solution of sucrose at 30 degrees Celsius. Therefore, when we say whether a particular solution is a saturated solution, we must state at what temperature it is formed.

There are two common methods, one is to simply increase the solvent content to dilute the solute and reduce it to below the solubility to become an unsaturated solution; The other is to raise the temperature or pressure and maintain it for a long time without consuming the quota, so that the solubility can be increased again and the unsaturated state will be reached in disguise.

A saturated solution is a solution in which the maximum amount of solute dissolved in a solvent (solubility) has reached a certain temperature and pressure. That is, when the solute is in contact with the solvent, the dissolution rate is equal to the precipitation rate. A solution in which the amount of solute does not reach the corresponding saturated state is called an unsaturated solution.

A solution in which the amount of solute exceeds the corresponding saturated state is called a supersaturated solution.

The unsaturated solution can be changed to a saturated hypothetical bridge solution by:

1. Increase the solute until there is a residue of solute;

2. Evaporation solvent (evaporation method can be used, preferably evaporation at constant temperature, and crystal precipitation should be seen);

3. Reduce the temperature of the solvent until there is crystal precipitation. (Note: The opposite is true for a small number of solutions, the higher the solvent temperature, the lower their solubility).