About the dissolution of objects, sublimation, etc

1 The temperature of the fish is below zero degrees Celsius.

And water reaches its freezing point at zero degrees Celsius.

So the water around the fish will freeze.

The incomplete solidification of the water makes the whole system form an ice-water mixture.

Physical Definition: The temperature of the ice-water mixture is zero.

So it's because of the solidification and exothermy of the water, the temperature of the fish drops from zero to zero, and the fish thaws.

2 Physically, it is said that a liquid substance no longer warms up after it has reached boiling (e.g., the temperature of water remains constant at 100 degrees Celsius after boiling).

And because the boiling point of oil is higher than that of water.

If the temperature of the oil pan is higher than 100 degrees Celsius, then the water will boil violently after entering the oil pan caused"**'

If the oil drops into the water, this will not happen.

Because the pot no longer heats up when it reaches 100 degrees Celsius, the oil does not reach the boiling point.

3 Will this question come up?

This is a theoretically unproven question.

At present, the experimental results are mostly that the hot solution solidifies first.

However, due to some experimental interference, it cannot be ruled out.

There are currently no convincing results.

I don't know if I'm satisfied or not.

1.When the temperature of the fish is low, the cold water will solidify, and the solidification will release heat, and the fish thawing will melt the ice and absorb heat, so that the fish will thaw quickly.

2.The boiling point of oil is high, much higher than the boiling point of water, and the water will boil violently, so it will appear"**"Phenomenon.

3.Hot milk solidifies first (this is common sense, just like hot and cold water freeze at the same time, and hot water freezes first, but I don't know exactly why).

I'm pretty sure of the answers to the other questions, but I don't know why for the third question.

Question 1: Water meets frozen fish solidification and exothermy.

Question 2: Water splashes into the oil pan, because the density of the water is large, so it will sink to the bottom, and the above phenomenon occurs when the water boils after encountering hot oil.

Don't dare to take the plunge on the third question.

1.The melting point of the fish is lower than the melting point of the water, the fish melts first, melts and absorbs heat, the temperature of the water around the fish decreases, the fish continues to absorb heat, the temperature of the water keeps dropping, and when the temperature of the fish reaches zero degrees Celsius, the water freezes and the fish melts.

2.Because the boiling point of water is lower than the temperature of oil, when the water enters the oil pan, the water boils violently (the temperature of the oil pan is more than 100 degrees Celsius).

The phenomenon of "**" occurs.

3.I'm not sure, so I can't say.

1. Melting: Melting is a phase change process that changes a substance from a solid state to a liquid state by heating it. Melting is an endothermic process to absorb heat. For example, ice turns into water, sea waves turn into liquid, and

2. Solidification: Solidification is the transformation of the liquid state into a solid state, and the exothermic process in the transformation process is the opposite of the process of melting

3. Vaporization: The object changes from liquid to gas, and there are two ways to absorb heat by evaporation and boiling. Evaporation is related to the surface area of the object, the velocity of the surface air, the temperature of the object, e.g., drying clothes, boiling water, etc

4. Liquefaction: The object changes from a gas to a liquid, and it is necessary to exothermic and vaporize the opposite

5. Sublimation: The object directly changes from a solid state to a gaseous state, which needs to absorb heat, for example: dry ice (solid carbon dioxide) will sublimate into carbon dioxide at room temperature, which can be used to preserve food

6. Condensation: The object directly changes from a gaseous state to a solid state, which needs to be exothermic, as opposed to sublimation, for example: the frozen clothes in the northern winter become dry, and on winter nights, the water vapor in the room often condenses into ice crystals on the window pane, and the "rime" on the branches

Melting: From solid to liquid, ice to water.

Coagulation: From a liquid state to a solid state, water to ice.

Vaporization: From liquid to gaseous, water into water vapor.

Liquefaction: From gaseous to liquid, water vapor to water.

Sublimation: From solid to gaseous, ice to water vapor.

Condensation: From gaseous state to solid state, water vapor to ice.

All of the above are physical reactions.

Good luck.

All metals melt when heated to the melting point, and the molten metal liquid (except mercury) will solidify if it is not heated further.

The liquid metal continues to be heated and vaporizes into vapor when it reaches its boiling point.

When the steam is exothermic, it liquefies.

So just put the metal in 10.

Ice sublimation, iodine sublimation.

Water vapor condensation, iodine vapor condensation.

That's it.

Directly from the solid belt gas is sublimation. For example, dry ice.

Melted, the solid turned into liquid, water and ice.

Solidify, the liquid turns into solid, water and ice.

Vaporization: liquid to gas.

Liquefaction: gas to liquid.

Categories: Education, Science, >> Science & Technology.

Problem description: Take the solid iodine in the physics book as an example, why does it not melt but sublimate after heating it with an alcohol lamp?

The teacher said that ice sublimates in winter, when the temperature is lower.

What is the difference in temperature requirements between sublimation and melting?

When it is heated rapidly, the temperature is exceeded, and the vapor pressure of the iodine is exceeded, then the solid iodine will melt, and liquid iodine will appear.

Sublimation - The direct change of matter from a solid state to a gaseous state is called sublimation.

Generally, substances have solid, liquid and gas three phases, and the change of state of matter is affected by temperature and pressure.

The conditions for sublimation and condensation of a pure substance are: the temperature and pressure of the vapor of the pure substance must be below the temperature and pressure of the three-phase point of the substance. If the vapor pressure of a solid pure substance is lower than its three-phase point pressure, the solid substance will be sublimated directly into a gaseous state when the temperature rises.

Conversely, if the pressure of a gaseous pure substance is lower than its three-phase point pressure. When the temperature is lowered below its three-phase point temperature, the gaseous substance will condense directly into a solid state.

So, ice sublimates in winter, when the temperature is lower (and drier, i.e., when the partial pressure of water vapor in the air is lower than the pressure megapascals at the triple point of water).

Similarly, the sanitary ball is made of naphthalene (C10H8), and its three-phase point has a temperature of about 180 degrees Celsius and a corresponding pressure of megapascals; The temperature of the three-phase point of iodine is open (about 114 degrees Celsius) and the corresponding pressure is megapascals. Their sublimation and condensation are easily observed at room temperature, in the air on the ground, and the three-phase diagram of CO2.

Three-phase diagram of water.

Three-phase diagram of iodine.

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Talk about the conditions of sublimation and condensation.

The sublimation of iodine is conditional.

jshlzx/klh/2/2009/text/zk09_260

Directly from the solid belt gas is sublimation. For example, dry ice.

Melted, the solid turned into liquid, water and ice.

Solidify, the liquid turns into solid, water and ice.

Vaporization: liquid to gas.

Liquefaction: gas to liquid.

Melting: From solid to liquid, ice to water.

Coagulation: From a liquid state to a solid state, water to ice.

Vaporization: From liquid to gaseous, water into water vapor.

Liquefaction: From gaseous to liquid, water vapor to water.

Sublimation: From solid to gaseous, ice to water vapor.

Condensation: From gaseous state to solid state, water vapor to ice.

The above are all physical reactions, good luck.

The process by which an object passes directly from a gas to a solid is called condensation. Frost.

Vaporization: water boiling produces water steam, only selling steam;

Liquefaction: Water vapor turns into liquid water when cooled;

Melting: The iron is heated into molten iron;

Coagulation: water freezes when cold;

Sublimation: Mothballs are gone after a long time, that is sublimation;

Ninghua: The ice on the windows in winter is formed by Ninghua.

Vaporization chamber: water becomes steam, liquefaction: steam becomes water, solidification: water becomes ice melting: ice becomes water.

Sublimation: Dry ice turns into CO2

Ninghua: CO2 turns into dry ice.

Because the external conditions will naturally melt when the melting point of the substance is reached, and it will naturally sublimate when the sublimation point is reached. As for what kind of process to carry out, it depends on the external conditions. The sublimation point is not necessarily higher than the melting point, it has a lot to do with the air pressure.

Sublimation refers to the phenomenon that a solid substance is directly transformed into a gaseous state without going through a liquid state.

The temperature at which the vapor pressure of a solid substance is equal to the external pressure is called the sublimation point of the substance.

Melting is a phase change process that changes a substance from a solid state to a liquid state by heating it.

Crystals have a fixed melting temperature called the melting point, which is equal to its freezing point. The endothermic temperature of the crystal rises and begins to melt when it reaches the melting point, at which point the temperature does not change. After the crystals have completely melted into a liquid, the temperature continues to rise until it vaporizes.

The physical process is not as isolated and static as the landlord thinks, it is a dynamic process.

Because these substances absorb heat and reach their melting point, they melt into liquids, for example, ice absorbs heat and melts into water.

When the temperature is very high and reaches the gasification temperature, it will be directly sublimated, and the sublimation point is not necessarily higher than the melting point, which has a lot to do with the air pressure.

Sublimation is the direct transformation of matter from a solid state to a gaseous state, such as dry ice cooling, which is the direct sublimation of carbon dioxide solids. Water can also be sublimated, and after washing in winter, the clothes are frozen, but they do not become liquid water, and the clothes are dry, which is also sublimation.

I worked hard to type, and the owner of the tower adopted.

When the temperature reaches the melting point of the substance, it melts into a liquid.

When the temperature is very high and reaches the vaporization temperature, it will be directly sublimated.

[Physics] [Liquefaction, Sublimation and Condensation] - How are clouds formed?

Sublimation A solid substance that does not go through the liquid stage directly becomes a gas. Camphor, iodine, naphthalene, etc. are all easy to sublimate.

In addition to atmospheric pressure sublimation, there are:

Vacuum sublimation. Since sublimation is related to the relative magnitude of the vapor pressure and the external pressure of the solid, reducing the external pressure can reduce the sublimation temperature, and the substances that cannot be sublimated or sublimate very slowly at atmospheric pressure can be sublimated by vacuum. Vacuum sublimation also prevents the sublimated substance from decomposing due to high temperature or being oxidized during sublimation.

Magnesium metal and samarium, titanium trichloride, benzoic acid, saccharin, etc. can be purified by this method.

Low temperature sublimation. In 1976, J W Mitchell proposed low-temperature sublimation technology, that is, the temperature and pressure are maintained below the three-phase point of the sublimated substance, so that it is sublimated at a very low pressure (a few millimeters of mercury), and after condensation, it is trapped in a cold trap and separated from impurities. This method is simple to operate, the product purity is very high, for example, it is difficult to purify hydrogen peroxide into high-purity reagent by general methods, purified by this method, cobalt, chromium, copper, iron, manganese, nickel and other miscellaneous wild materials can be reduced from 1000ng ml at one time.

Sublimation: Solid gas (disappearance of mothballs in the closet).

Liquefaction: gas-to-liquid (eat the freezer in summer, and white gas is produced on the freezer) Vaporization: liquid-to-gas (the evaporation of rainwater after rain, evaporation belongs to vaporization) Condensation: gas becomes solid (in winter nights, indoor water vapor often condenses into ice crystals on the window glass) Coagulation: liquid becomes solid (water freezes).

Melting: solidification liquid (ice into water).