What is the principle of stirring to dissolve table salt quickly?

This question is related to the question of the rate of diffusion.

First of all, we understand a problem: when two solutions of different concentrations are in contact, the diffusion rate of the solute on the contact surface is proportional to the difference in the concentration of the solution. (The reason is:.)

On both sides of the interface, the solutes of both solutions are diffusing towards each other, and the higher concentration of the solution diffuses faster. If you don't understand this paragraph, you can just look at the above, I don't express it very well)

Let's discuss the problem of dissolving table salt: after the salt is thrown into the solvent, a very thin and saturated solution is quickly formed in the manifestation of salt (the thickness of the saturated solution is related to the dissolution time), and then the solute of this layer of saturated solution diffuses to the solute of the surrounding unsaturated solution, and the solute of the unsaturated solution diffuses to the solvent of the outer layer excluding the solute, and the original saturated solution becomes unsaturated, and continues to dissolve the solute to form a saturated solution, producing potential energy for continued diffusion. Natural dissolution is the repetition of this process until the solute is dissolved or the solution is saturated.

Once stirred, this solution system with a regular concentration difference is broken, and the unsaturated solution or even pure solvent surrounds the solute, forming a large concentration difference, accelerating diffusion, and thus speeding up the dissolution.

Work is done on the salt and solution, so that the internal energy is added, so that the molecular movement is enhanced, and the diffusion is accelerated.

Accelerated Brownian motion of molecules.

Sodium chloride. It is the main component of salt and is an ionic compound.

Pure sodium chloride crystals are colorless and transparent cubic crystals, and due to the presence of general impurities, sodium chloride is white cubic crystals or fine crystal powder with a specific gravity of 2165 (25 4), melting point 801, boiling point 1442, density of grams of cubic centimeters, salty taste, containing impurities easy to deliquescent; Soluble in water or glycerol.

Insoluble in ethanol.

Insoluble in hydrochloric acid, aqueous solution neutral and conductive. If you heat the brine, you will see white crystals. Evaporation crystallization.

As the water evaporates, the concentration of the salt solution becomes higher and higher until it becomes a saturated solution. Continue to evaporate the water, and the dissolved salts will precipitate out in the form of crystals.

<> there are two things that happen. If the saline is a supersaturated solution, some of the undissolved salts in the solution will dissolve. Increase the concentration of edible brine.

If heated for a long time, the salt will precipitate out of the brine due to the large evaporation of the water. The dissolution of salts in water is an ionization process along with ionic bonding.

will release heat. Cane sugar.

Dissolution is a process of dilution and dispersion.

The sucrose molecule exists as a whole and does not break. It is simply a process by which molecules are diluted or dispersed in water. At first, it will slowly dissolve, and the more you add it, the more saturated it will be, and then it will not be able to dissolve.

If heated, a part of it can be dissolved, and salt crystals will precipitate after cooling. Because of the solubility of water to salt.

It increases with increasing temperature, but there is also a certain limit, and when the temperature decreases, its solubility also decreases. Sodium chloride is the main component of table salt and does not react when heated to 100 degrees. But today's salt contains iodine, which evaporates when heated. Nitrite.

It is inedible!

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After that, white crystals will appear, and then after the water evaporates, the concentration in the salt will become higher and higher, and a saturated solution will be produced, and then the water will also evaporate and become crystal precipitation.

First of all, the salt may slowly dissolve, and when it reaches the saturated state, it will not dissolve, and then the water will evaporate after continuing to be heated, and after it has cooled down in the saturated state, a part of it will be analyzed into salt crystals.

Some crystals may be produced. When the aqueous solution reaches saturation, continuing to heat will allow the water to evaporate, and some salt crystals will be produced.

Stirring and heating can speed up the movement of water molecules, and can also speed up the contact opportunity between salt and water, thereby accelerating the dissolution rate of salt, the size of solid particles determines the size of the contact area between solid and water, and can also change the dissolution rate, and the solid grinding increases the contact area between solid and water, which also accelerates the dissolution rate of solid.

Add some warm water and salt to dissolve faster.

Dissolution factors affecting table salt:

Ingredients: salt, hot water, cold water, thermometer, bowl, chopsticks.

Steps: 1. Take two bowls, add an appropriate amount of cold water (about 1 3), and add lumpy and powdered salt respectively (the relationship between the speed of dissolution and the size of the particles).

2. Stir with chopsticks until all dissolved (stirring can accelerate melting) 3. Add cold water again (the relationship between melting and solvent and solute) 4. Take two bowls and add an appropriate amount of cold water and hot water (about 2 3) to add the same quality of lumpy salt (temperature and dissolution) respectively

Conclusion: The dissolution factors of table salt are related to temperature, particle size, stirring, amount of solvent and solute. The higher the temperature, the smaller the particles, the more water you have, and the faster it dissolves.

The stirring method can speed up the dissolution of table salt. It can speed up the movement of water molecules, and also increase the chance of contact between water and salt.

Stirring and heating can speed up the movement of water molecules, which can also speed up the contact opportunity between salt and water, thereby accelerating the dissolution rate of salt. The size of the solid particles determines the size of the contact area between the solid and the water, and can also change the dissolution rate, and the grinding of the solid increases the contact area between the solid and the water, which also accelerates the dissolution rate of the solid.

In the diffusion movement, we will find that the higher the temperature, the faster the diffusion. When observing Brownian motion, it is also observed that the higher the temperature, the more pronounced the motion of suspended particles. These states of affairs show that the irregular movement of molecules is related to temperature, and the higher the temperature, the more intense this movement becomes.

Therefore, we call the irregular motion of molecules that never stops as thermal motion.

The movement of a molecule is related to temperature and molecular mass, but if you want to really understand it, you can only see it under an electron microscope. The movement of molecules is also related to the interval between molecules, for example, at room temperature, the movement between gases and gases will be very fast, and it only takes 1 day at most to observe their motion phenomena; Liquid takes about 1 month; Solids take a few years.

And we will find that looking at the gap between molecules: gases are larger than liquids and larger than solids (molecular gaps), therefore, the movement of molecules is related to the interval of molecules.

Fill one beaker with half a cup of hot water and another beaker with the same beaker with an equal amount of cold water. Using a dropper to pour a drop of ink into the bottom of each of the two cups, I noticed that the color of the beaker filled with hot water changed quickly. It shows that the thermal motion of a molecule is related to temperature.

Summary. From a physical point of view, stirring reduces the concentration of the solution next to the salt ions, accelerates the movement of molecules, and naturally dissolves faster than without stirring.

Under the same conditions, stirring salt dissolves faster than not stirring salt.

From a physical point of view, stirring reduces the concentration of the solution next to the salt ions, accelerates the movement of molecules, and naturally dissolves faster than without stirring.

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Common ways to speed up dissolution:

1. Heating or cooling. Depending on the nature of solutes, some substances are higher in temperature, lower solubility. On the contrary, like some substances dissolved in solvent exothermics, the temperature should be lowered as much as possible, and the dissolved endothermic should be heated to dissolve.

2. Grinding. Try to make the contact surface between the dissolved matter and the solvent larger, that is, the powder contact is maximized.

3. Stir. The dissolved residue is diffused in the solvent from the high solubility to the low solubility, so stirring can also speed up the dissolution.