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Anonymous users2024-02-12The melting point is the minimum temperature required for a substance to change from a solid state to a liquid state. Melting point is a physical property of a substance. The melting point of a substance is not fixed, and there are two factors that have a great influence on the melting point.
One is pressure, which is usually referred to as the melting point of a substance, which usually refers to the situation at an atmospheric pressure; If the pressure changes, the melting point also changes. There are two different cases of the change in melting point with pressure For most substances, the melting process is the process of increasing volume, and when the pressure increases, the melting point of these substances increases; For a substance like water, unlike most substances, the volume of the process by which ice melts into water decreases (as does the metal bismuth, antimony, etc.), and the melting point of ice decreases when the pressure increases. The other is the impurities in the substance, what we usually call the melting point of the substance, which usually refers to the pure substance.
But in real life, most of the substances contain other substances, such as a small amount of other substances in the pure liquid substance, or called impurities, even if the number is small, the melting point of the substance will change greatly, for example, there is salt in the water, the melting point will drop significantly, seawater is the water with salt, and the temperature of seawater freezing in winter is lower than that of river water, which is the reason.
The melting point is essentially the temperature at which the solid and liquid phases of the substance can coexist and be in equilibrium, taking ice melting into water as an example, the melting point of ice at an atmospheric pressure is 0, and when the temperature is 0, ice and water can coexist, if there is no heat exchange with the outside world, the state of ice and water coexistence can remain stable for a long time. In various crystals, the interaction forces between particles are different, and therefore the melting point is different. For the same kind of crystal, the melting point is related to the pressure, and the melting point of the substance at a pressure of 1 atmosphere is generally taken as the normal melting point.
At a certain pressure, both the melting point and the freezing point of the crystalline substance are the same. The melting point of a substance that expands in volume during melting increases when the pressure increases.
Therefore, adding sugar is actually adding impurities to it, which can reduce the melting point of ice.
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Anonymous users2024-02-11When a hydrophilic substance such as starch is added to the water, the melting point will increase after freezing.
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Anonymous users2024-02-10I mean, in chemistry, sugar is also a type of salt, right? Instead of raising the melting point of ice, it should be lowered.
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Anonymous users2024-02-09The main component of rock sugar is sucrose, and there are three main factors that affect its dissolution rate:
The temperature of the solvent rock sugar particle size is stirred or not.
Therefore, there are three ways to speed up the dissolution of rock sugar: increase the temperature of the solvent; Crush the rock sugar; Stir while dissolving.
Specific reasons: From a microscopic point of view, each of the above methods increases the probability of molecular collision between sucrose molecules and solvents through different ways, thereby increasing the rate of diffusion and hydration of sucrose molecules, and increasing the rate of dissolution.
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Anonymous users2024-02-08The temperature of the water is directly proportional to how quickly the rock sugar dissolves, and a little longer will also help to dissolve.
Crack the rock sugar first, pour it into the water and stir it, which can accelerate the dissolution of the rock sugar.
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Anonymous users2024-02-07Rock sugar belongs to the blind aggregate of sugar crystals in front of the great gods.
Melting of rock sugar: refers to the change of rock sugar from solid to liquid at room temperature, when it occurs, the temperature must reach the melting point of rock sugar, in this process, only rock sugar changes, no other substances participate.
Dissolution of rock sugar: refers to the dissolution of rock sugar, which refers to the diffusion process of rock sugar dispersion into a single molecule or ion in another liquid substance. This process does not require heating, but there must be liquid, so it is "dissolved" with three points of water.
Melting can be carried out at any temperature, and in general, the higher the temperature of the dissolving liquid, the faster it dissolves.
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Anonymous users2024-02-06Summary. Because rock sugar has high crystallinity and low solubility, it is not easy to dissolve or melt even at room temperature. However, if the ambient temperature is too high or humid, and the rock sugar is not stored in a dry and ventilated environment, it will cause the rock sugar crystals to be destroyed, which may make the rock sugar soft or partially dissolved.
In addition, if the rock sugar is placed in hot water or heated, it will gradually melt the rock sugar, which is often used in cooking, making pastries and sweet and sour dishes. So, if you need to use rock sugar for cooking or making desserts, it's best to smash or cut it into small pieces first so that it melts faster.
No. I'm still a little confused, can you be more detailed?
Because rock sugar has high crystallinity and low solubility, it is not easy to dissolve or melt even at room temperature. However, if the ambient temperature is too high or humid, and the rock sugar is not stored in a dry and ventilated environment, it will cause the rock sugar crystals to be destroyed, which may make the rock sugar soft or partially dissolved. In addition, if the rock sugar is placed in hot water or heated, it will gradually melt the rock sugar, which is often used in cooking, making pastries and sweet and sour dishes.
So, if you need to use rock sugar for cooking or making desserts, it's best to smash or cut it into small pieces first so that it melts faster.
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Anonymous users2024-02-05Speeding up the dissolution of rock sugar in water is mainly by speeding up the movement of microscopic particles, which will speed up the dissolution.
heating, the thermal movement of molecules or ions increases;
stirring, artificially accelerating the movement of microscopic particles in the solution;
Therefore, both of the above conditions can speed up the dissolution.
In addition, increasing the surface area of solids in contact with water also increases the rate of dissolution.
Therefore, grinding fine rock sugar will also increase its dissolution rate.
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Anonymous users2024-02-04Factors influencing the dissolution rate of solids in water: stirring, temperature, and solid particle size; 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
So the answer is: stirring, temperature, solid particle size; Stir; Warming; Grind the solids
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