Melting and solidification 15, characteristics of solidification and melting

Melting ice is indicated to have a temperature of zero degrees Celsius, (because the melting point of ice is zero degrees Celsius), and when it is moved to a room at zero degrees Celsius, it will not continue to melt because it cannot absorb the heat needed to continue melting. If the water at zero degrees is placed in a room at zero degrees, the temperature is equal and there is no heat transfer, so the water will not release heat and solidify into ice.

The key here is to be clear that the two processes of state change, melting and solidification, for crystals like ice, occur under the conditions of; 1. The temperature should reach the melting point (or freezing point).2.It is necessary to continue to absorb heat (or release heat).Two conditions are indispensable.

Ice, which remains unchanged at zero degrees Celsius during the melting process, but is endothermic. The condition for heat transfer between two objects is that there is a temperature difference, and there is no temperature difference between the ice at zero degrees and the room at zero degrees, so there is no heat transfer, and the ice cannot absorb the heat, so it cannot continue to melt.

In the same way, water at zero degrees Celsius remains constant during the solidification process, but is exothermic. Now that the water is placed in a room at zero temperature, there is no temperature difference, so there is no heat transfer, and the water cannot solidify into ice.

Move the melting ice to a room at zero degrees Celsius, and the ice will continue to melt because the melting ice temperature is higher than zero, and it can melt some of it. Zero-degree water is placed in a room at zero temperature, and the water cannot solidify into ice because it needs to absorb temperature.

Neither. Ice melting requires heat absorption (there is a temperature difference, above 0 degrees), and the room at zero degrees and the ice that is melting are both 0 degrees.

The solidification of water at zero degrees into ice requires exothermy, and the reason is similar.

None of them can't, kids. I guess I'm in junior high school. To solve this problem, you just need to figure out a problem.

If the ice is to melt, it must absorb heat, and if the water is to freeze, it must be exothermic. At the same time, one of the peculiarities of water is that its zero point of melting and freezing is zero, so, problem 1: it can't absorb more heat and will stop melting; Question 2:

Ice cannot melt because ice needs to reach its melting point and constantly absorb heat to melt. Although zero degrees Celsius reaches the melting point of ice, it cannot absorb heat and cannot melt. Therefore, water cannot be exothermic and solidified into ice.

No, the ice should absorb heat, but not heat; The water needs to be heated, but there is no place to put it.

No, because the ice starts to solidify at 0 degrees.

1.Not. Because it will freeze after a few degrees below 0, and 0 degrees will not return. 2.Not. Because 0 degrees does not freeze. Only a few degrees below 0 will it solidify and freeze.

1) Can be melted ''''

2) No, because I said it's better for you to try it yourself.

Hehe!!

Endothermic Endothermic heating.

Solid——— liquid ——— gaseous. Sublimation, condensation.

National income honestly,

Just studying physics, right?

into an ice-water mixture.

If you don't believe me, ask your teacher.

Melting: Crystalline substances: hypo, ice, quartz crystals, Amorphous substances: rosin, paraffin glass, asphalt, beeswax table salt, alum, nai, various metals.

Melting characteristics: solid-liquid coexistence, endothermy, constant temperature Melting characteristics: endothermy, first soft and thin, and finally into liquid, the temperature continues to rise.

Melting conditions:

Melting point is reached. Continue to absorb heat.

Solidification: Definition: The change of a substance from a liquid state to a solid state is called solidification.

Solidification characteristics: solid-liquid coexistence, exothermic, constant temperature Solidification characteristics: exothermic, gradually thickening, viscous, hard, and finally solid, the temperature continues to decrease.

Freezing point: The temperature at which the crystal solidifies. The melting point and freezing point of the same substance are the same.

Conditions of coagulation:

Freezing point reached.

Continue to exothermic. The difference between melting, melting, and melting:

1. Melting refers to the transformation of ice or snow into water due to temperature or sunlight.

1. Turn into liquid.

The ice cream melted in the sun.

2. For example, ice and snow change from frozen to liquid.

Spring is coming, and the ice in the creek is melting.

2. Melting is the process of changing the substance from a solid state to a liquid state, and it is a process of changing the state of matter, which requires heating, so it is "melted" next to "fire". For example, when ice is heated to melt into water, the wax is heated to melt, sometimes called melting.

3. Dissolution refers to the dissolution of solids, which refers to the process of dissolving solids in liquids, and dissolution Specifically, it refers to the diffusion process of a solid substance dispersed 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. For example, sugar is dissolved in water to make sugar water.

Classification is based on changes in the state of substances.

Liquefaction: The process by which a substance changes from a gaseous state to a liquid state. Vaporization: The process by which a substance changes from a liquid state to a gaseous state.

Condensation: Condensation refers to the phenomenon that a substance changes directly from a gaseous state to a solid state, which is a change in the state of matter when the temperature and air pressure are lower than the three-phase point.

Sublimation: The process by which a substance changes from a solid state to a gaseous state. Melting: The process by which a substance changes from a solid state to a liquid state.

Extended content. Examples of the actual phenomenon of Ninghua:

1.The long-used light bulb will turn from transparent to black, which is heated when the light bulb is working, and the tungsten vapor formed by the heating and sublimation of the tungsten filament is condensed on the wall of the light bulb into a very thin layer of solid tungsten

2.On winter nights, the water vapor in the room often condenses into ice crystals on the window panes; "rime" on tree branches; The popsicle taken out of the refrigerator formed a layer of "frost"; Another example is the formation of "frost" in nature, etc., which are all condensation phenomena.

3.Rime in winter.

4.When iodine vapor is cold, iodine particles appear on the inner wall of the flask.

The process by which a substance changes from a solid state to a liquid state is called melting, and when it melts, the substance absorbs heat. The process by which a substance changes from a liquid state to a solid state is called solidification, and the substance is exothermic when it solidifies.

While the ice in the beaker is melting, the ice in the tube is not melting. Because the temperature remains unchanged at 0 while the ice in the beaker is melting, the temperature of the ice in the tube can reach 0 (melting point), but the ice in the tube and the ice-water mixture in the beaker are at the same temperature, there is no temperature difference, and they cannot continue to absorb heat, so the ice in the tube will not melt.

1. Concept. Melting: When a substance is converted from a solid state to a liquid state, this phenomenon is called melting.

Solidification: When a substance is converted from a liquid state to a solid state, this phenomenon is called solidification.

Vaporization: The conversion of a substance from a liquid state to a gaseous state, a phenomenon called vaporization.

Liquefaction: When a substance is converted from a gaseous state to a liquid state, this phenomenon is called liquefaction.

Sublimation: The direct conversion of matter from a solid state to a gaseous state is a phenomenon called sublimation.

Condensation: The direct conversion of matter from the gaseous state to the solid state is called condensation.

2. Differences. 1. Melting should absorb heat, such as ice absorbing heat and melting into water; Solidification is exothermic, such as water exothermic solidification into ice.

2. There are two ways of vaporization: evaporation and boiling, evaporation occurs on the surface of the liquid, which can be carried out at any temperature, which is slow.

3. Sublimation and endothermy, condensation and exothermy.

During the phase transition, i.e., when melting and solidifying, the temperature of the object does not change.

Melting refers to the process of heating a substance from a solid state to a liquid state. Melting requires the absorption of heat and is an endothermic process. Crystals have a certain melting temperature and are called melting points. Amorphous does not have a certain melting temperature.

Coagulation refers to the process of cooling a substance from a liquid state to a solid state. Solidification requires the release of heat, which is an exothermic process. Solidification is the reverse process of melting.

Melting phenomenon: ice water.

Paraffin wax liquid [high temperature].

Plastic Leather Shenwu plastic droplets [high temperature].

Iron Molten iron [high temperature].

Copper blind late copper water [high temperature].

Coagulation phenomenon: combustion or.

Water ice. Wax liquid paraffin.

Plastic droplets plastic.

Molten iron iron. Copper water copper.

There are many examples, most of the metal can be melted at high temperatures, and solidify after cooling!

Understood, there is a new question to ask for help,