Salt water, sugar water, clear water, whichever freezes first

Today I encountered an experimental problem in "Winter Vacation Life", which is an experiment of salt water, sugar water, and clear water, which freezes first. I filled the three cups with salt water, sugar water, and water. Label the cups to distinguish them and place them in the freezer compartment of the refrigerator.

Then I watched every half hour, and the first time I looked, the water in the three cups was not frozen. The second time, only the cup of water had a thin layer of ice. The third time I opened the refrigerator to look, I found that there was a thick layer of ice in the clear water cup, a thin layer of ice in the sugar water cup, and there was still no ice in the salt water cup.

The fourth time I looked at it, there was a thin layer of ice in the brine cup, and the water in the other two cups was thick with ice. At this time, I knew the answer: clear water froze the fastest, followed by sugar water, and salt water froze the latest.

Indicates that the coagulation temperature of brine is the lowest. That's why people sprinkle salt on the road on snowy days.

The water freezes first.

When water is about to freeze, hydrogen bonds will be formed between water molecules, and regular crystals will be formed, so if there are other substances dissolved in the water, it will hinder the formation of crystals, so that the freezing point of water will decrease;

So, how much does the freezing point of the solution drop? It depends on the concentration, such as brine, the more salt is added to the water, the lower the freezing point. For example, if you add 50 grams of salt to two litres of water, the freezing point of the brine will be about -zero degrees Celsius.

Salt water, sugar water, clear water, which freezes first writes a reward.

Salt water, sugar water, clear water, whichever freezes first

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Servant Wen Fu Banhui.

2019-12-15 ta received more than 10,000 likes.

Concern. The water freezes first.

When water is about to freeze, hydrogen bonds will be formed between water molecules, and regular crystals will be formed, so if there are other substances dissolved in the water, it will hinder the formation of crystals, so that the freezing point of water will decrease;

Salt does not freeze water quickly, salt can quickly turn ice into water. Snow removal and salt sprinkling embodies the three physical and chemical properties of table salt:

1. Solubility: instant salt is easily dissolved in water.

2. Moisture absorption: there is a thin film solution on the surface of salt, and when its vapor pressure is lower than the water vapor partial pressure in the air, the salt will adsorb the moisture in the air and deliquescent.

3. Low freezing point: The freezing point of the saline solution is low. If the salt solution contains 20% salt, its freezing point will drop to -16.

Benefits of Eating Salt:

1. Maintaining the osmotic pressure of extracellular fluid, salt plays an important role in maintaining osmotic pressure and affects the movement of water in the human body.

2. Participate in the regulation of acid-base balance in the body.

3. Chloride ions are involved in the production of gastric acid in the body.

4. Salt also plays a role in maintaining the normal excitability of nerves and muscles.

5. It has the effects of clearing fire and detoxifying, cooling blood and nourishing kidneys, and laxative.

6. Salt has strong penetration, which can relieve greasyness, remove fat and fish, and maintain the original taste of food, making food easy to digest.

All you need is a lighter, a straw, a glass of water and some salt. It's also very simple, sprinkle some salt into the water first, then seal one end of the straw with your finger, burn the other end of the straw with a lighter, then quickly insert the straw into the water, then let go of your fingers, and after 5 seconds, quickly pull the straw out of the water, so that the water in the cup will freeze in a few seconds.

Clear water freezes before salt water and sugar water. Typically, water oneStandard atmospheric pressureThe freezing point of the lower icing is 0. That is, under normal circumstances, water will become solid in its liquid state at 0.

And because salt water and sugar water are not pure water, they contain two impurities in the water, salt and sugar, respectively, therefore, the freezing point of salt water and sugar water will be lowered, so that it freezes later than clear water.

The difference in the freezing time of salt water, sugar water and clear waterWhen comparing the freezing time of salt water, sugar water, and clear water, it is important to understand that the freezing point of different liquids is affected by the purity of the water. If the water contains more impurities, then the lower the freezing point of this liquid. In other words, the freezing point is related to the concentration of the solution, and the higher the concentration of the solution, the lower the freezing point and the lower the temperature at which the solution freezes.

Depending on the situation, if the temperature of two glasses of water has just reached zero, this is if salt is added to a glass of water, then it will freeze first, because when the salt dissolves, it has to absorb heat and can help freeze.

But if it starts with a glass of salt water and a glass of ice water, then it is the ice water that freezes first. Contrary to the above, the lower the temperature, the lower the solubility of the salt, the gradual precipitation of the salt, and the exothermic process of salt crystallization, all of which slow down the freezing process.

When doing water freezing experiments, adding more salt to the crushed ice is to quickly absorb heat and freeze quickly.

When the ice salts are mixed together, two effects occur at the same time: one is to greatly accelerate the melting rate of the ice, and when the ice melts, it has to absorb a lot of heat; The other is the dissolution of salt, which also absorbs the heat of dissolution. As a result, a large amount of heat can be absorbed in a short period of time, so that the temperature of the ice-salt mixture drops rapidly, which is much lower than that of ice alone.

The temperature of the ice-salt mixture is based on the percentage of salt mixed into the ice.

And decided, such as the amount of salt used in ice, the minimum temperature can reach -21.

Ice salt bath:

The cooling principle of the ice salt bath and the freezing point of the solution.

Decline. When salt and ice are evenly mixed together, the ice melts slightly into water due to the absorption of environmental heat, and the salt dissolves when it meets water, so that the surface water forms a concentrated salt solution.

Since the freezing point of the concentrated salt solution is lower than that of pure water, and the system is where the concentrated salt solution and ice coexist, the temperature of the system must drop to maintain this coexistence (the coexistence temperature of the concentrated salt solution and ice should be lower than that of pure water). This will cause more ice to melt into water to dilute the concentrated salt solution, reducing the temperature of the system due to a large amount of endothermy during the melting process.

Clear water freezes before sugar water. Water freezes first because sugar water is denser than water. The denser the liquid, the harder it is to freeze, and the less dense it is, the easier it is to freeze.

The density of ice is smaller than that of water, and when it turns from water to ice, it needs to change the density.

Conditions: 1. The temperature of icing should be less than or equal to 0 degrees Celsius.

2. It is required to have a frozen core in the water. With the frozen nucleus, the water molecules are arranged in the crystalline structure of the ice. The water of rivers, lakes and seas, and the tap water used in cities all contain impurities, and these impurities are frozen nuclei.

So when it reaches zero degrees Celsius, it freezes. However, for pure water, even if the temperature is below 0, it is difficult to freeze because there is no freezing core, and it cannot become ice.

If you put some small ice crystals, or sand grains in a cup of pure water, the water molecules have a core or are attached to Zheng Chai and are arranged according to the crystal structure of the ice, and become ice.

After adding sugar or salt to the water, the density of the solution will increase accordingly, and the freezing point of the liquid is related to the density, when the density increases, the freezing point will decrease, so it is not easy to freeze after putting sugar and salt in the water, and it will still freeze when the temperature is lower than the freezing point of the solution.

In winter, you can sprinkle salt on the melting snow and ice so that it becomes salt water and will not freeze again. Because the freezing point of salt water is lower than that of water, for example, the freezing point of seawater is about, so that the salt water does not solidify easily, and the snow and ice melt.

If there is no salt, the ambient temperature is not easy to melt even if it is higher than 0 degrees, after the salt is sprinkled, the condensation nucleus is provided, and the temperature is slightly higher than 0 degrees to melt, and the melting point of the brine solution is generally lower than 0 degrees, and the two reasons combine to make it easier to melt snow when salt is sprinkled. (If the solution contains 20% salt, its freezing point will be reduced to -16.) Taking advantage of the low freezing point of salt, salt can be used to prevent ice formation on highway pavements and airport runways in the cold winter. ）

The water freezes at 0 under standard conditions, and the freezing point is lowered by adding salt and sugar (e.g. to -2), so it will no longer freeze at 0, but it will still freeze if it continues to cool down to -2.

No, ice can only be formed at a certain temperature.

Ice is a crystallization formed by the orderly arrangement of water molecules, which are joined together by hydrogen bonds to form a very "open" (low-density) rigid structure. The spacing between the O—O nuclei closest to the water molecule is about 109°, which is very close to the 109°28 bond angle of an ideal tetrahedron.

However, the O-o spacing of each water molecule that is only adjacent and not directly bound is much larger, and the farthest is reached. Each water molecule can combine with 4 other water molecules to form a tetrahedral structure, so the coordination number of the water molecule is 4.

No, ice can only be formed at a certain temperature.

No, this mixture dissolves in water without significant temperature effect.

Sodium nitrate and dissolved in water cooled significantly, add water in the container, add sodium nitrate, and put it in a large container after filling the water in a small metal container, suspend it through water, and the water in the middle container can freeze.

8.Lipid Commentary School Book (1) "Fat Yan Zhai Commentary on Dream of Red Mansions", Huang Lin proofreading, 120 times, published by Qilu Publishing House in 1994;