The more the merrier, the more difficult questions about the change of physical state of matter5

There are three basic physical states of matter: solid, liquid, and gaseous. The process by which a substance changes from one state to another is called a change in the state of matter. All changes in the state of matter are physical changes! Supplement: The process of change of state of matter is as follows:

Melting: Solid liquid state (endothermy).

Coagulation: Liquid solid state (exothermic).

Vaporization: Liquid vapor state (endothermy).

Liquefaction: vapor liquid (exothermic).

Sublimation: Solid vapor state (endothermy).

Condensation: vapor solid state (exothermic)."

Fog and dew are made up of small water droplets, so they are formed by liquefaction of water vapor. Frost and snow are formed by the condensation of water vapor, and hail is supposed to be formed by the condensation of rain as it falls. Ice flowers are formed by water vapor condensation, sanitary balls become smaller due to slow sublimation, lamp tubes become blackened is condensation, filament thinning is sublimation, ice is melted into water, and molten iron is solidified into steel.

PS: Sublimation: refers to the phenomenon that a solid substance is directly transformed into a gaseous state without going through a liquid state, and it is endothermic.

Condensation: refers to the phenomenon that a substance directly changes from a gaseous state to a solid state without going through a liquid state, and is exothermic.

Liquefaction: The liquid becomes gaseous after evaporation or boiling, and it is endothermic.

Vaporization: gaseous state is converted into liquid state, exothermic.

Melting: from solid to liquid, endothermy.

Coagulation: Conversion from liquid state to solid state, exothermy.

Fog and dew are liquefaction, frost is condensation, hail and snow are coagulation or condensation, white vapor is liquefaction, ice flowers are condensation, the sanitary ball becomes smaller is sublimation, lamp tube blackening is condensation, filament thinning is sublimation, ice into water is melting, and molten iron into steel is solidification.

Liquefaction, liquefaction, condensation, condensation, liquefaction, condensation, sublimation, sublimation, sublimation, melting, coagulation.

Liquefaction one. Liquefaction.

Ninghua to. Ninghua gives.

Liquefaction points. Ninghua sublimation.

Sublimation. Sublimation.

Melt. Congeal.

There is always water vapor in the air, and the water vapor is a colorless and transparent gas that is invisible. The "white steam" we see every day is not water vapor, but small water droplets formed by water vapor liquefied when it is cold.

1. How are clouds formed?

When the air with a lot of water vapor rises into the air, the water vapor temperature decreases and liquefifies into small water droplets or condenses into Xiaoice crystals, and these small particles can be lifted by the air updraft to form floating clouds, so the clouds are composed of a large number of water vapor and Xiaoice crystals.

2. How is rain formed?

Under certain conditions, the small water droplets and Xiaoice crystals in the cloud become larger and larger, and when they reach a certain level, the updraft cannot support them, and they will fall, and in the process of falling, the Xiaoice crystals melt into water droplets and fall to the ground together with the original small water droplets, forming rain.

3. How is fog formed?

Fog generally appears early in the morning. Fog is formed when water vapor in the air meets cold air or when the ground temperature drops suddenly, it liquefies into small water droplets and floats in the air and on the dust.

4. How is dew formed?

When the ground temperature drops, the water vapor in the air will liquefy into small droplets that attach to the ground or flowers and plants when the ground temperature drops, forming dew.

5. How is snow formed?

In winter, sometimes the updraft is weak, and the water vapor in the clouds is cooled and condenses directly on the Xiaoice crystals to form snowflakes, which fall to the ground surface to form snow.

6. How is frost formed?

It is formed by the direct condensation of water vapor in the air by cold. On winter nights, when the temperature of the ground drops rapidly below zero, the water vapor in the air quickly condenses on the ground to form small solid crystals, known as frost.

7. How is hail formed?

In summer, the updrafts are strong and unstable, and small water droplets are condensed in the air convection into Xiaoice hail. Xiaoice hail blocks merge with Xiaoice crystals and small water droplets in the process of flow to form large ice blocks, and when such ice blocks increase to a certain extent, the air flow cannot support them, and they fall to the ground to form ocean hailstones.

8. Artificial rainfall:

Usually artificial rainfall uses solid carbon dioxide (dry ice) to directly sublimate into gas to absorb a large amount of heat, so that the temperature of the surrounding air drops rapidly, and the water vapor in the air will liquefy into small water droplets or directly condense into Xiaoice crystals when cold, so that artificial rainfall can be realized.

9. Cloud and fog effect on the stage:

Dry ice is often used to absorb a lot of heat during sublimation to reduce the air temperature, so that the water vapor in the air liquefies into small water droplets, which can be directly condensed into Xiaoice crystals, forming a cloud and fog effect on the stage.

Liquefaction, liquefaction, condensation. I didn't learn physics well in junior high school on the first floor. White gas is not a gas but a liquid, and it is obviously liquefied (for such problems, it should be noted that gas is invisible and intangible, and white gas and water vapor in life are liquid).

1) Table salt is NaCl NaCl is decomposed by heat, and if it is put in too early, it will be completely decomposed.

2) In the indoor water vapor condensation, the water vapor temperature is high, and the glass temperature is low, the water vapor will condense.

3) Alcohol vaporization and endothermy.

4)0 The surface under the ice can be seen as an ice-water mixture.

5) When barefoot, the feet sweat and quickly evaporate on the charcoal to absorb heat. Therefore, when a person walks quickly, the sweat evaporates and absorbs heat to ensure that the person is not burned by the high temperature. Hope.

1.Putting salt too early in the stir-fry will fry the water in the dish, because after adding salt, the cells will transfer the water in the cells to a high concentration due to the high concentration of salt outside.

2.The ice flower is in the window, because the outside temperature is low in winter and the indoor temperature is high, and on both sides of the glass is a low-temperature outside, and on the other side is a high-temperature house, yes, there is a temperature difference on both sides of the glass, causing the indoor water vapor to condense and freeze on the inner glass, so the ice flower is on the inside.

3.In summer, the indoor temperature is high, and the alcohol will volatilize at a higher temperature, and volatilization is an endothermic process, so when the thermometer is put into the alcohol, the temperature of the thermometer is lower than the temperature placed in the room due to the endothermic effect of alcohol.

4.The underside of the ice is in contact with the water, and no matter what the outside is at any degree, the place where the ice and water mix is 0, that is, it is 0 on the contact surface

5. Due to long-term exercise on the soles of the feet, there will be very thick calluses at the lower level, which makes the heat transfer speed very slow, and the calluses are dead cells, which have no nerves, so people will not feel pain.

Commonly used liquids in capillary glass tubes of thermometers commonly used in homes and laboratories are: mercury, kerosene, alcohol, and other organic solvents (e.g., acetone, methanol, benzene, ether, glycerin), etc.

Normally, mercury does not stain, even when it is the color of mercury itself (silver); Kerosene, alcohol, etc., are dyed red in order to be eye-catching and easy to observe.

It is often used as a thermometer liquid column liquid should meet the following conditions: aSensitivity to heat (i.e., good characteristics of thermal expansion and contraction); b.The melting and boiling points span a large one; c.Glass tubing does not infiltrate wetting liquids.

There are three commonly used liquids: mercury (-39 357) alcohol (-117 78) kerosene (generally -30 150) Therefore, according to the different melting and boiling point ranges of the three liquids, mercury thermometers, alcohol thermometers, and kerosene thermometers are suitable for occasions with different temperature measurement ranges.

According to the difference in the characteristics of thermal expansion and cold contraction of the three liquids, the three thermometers are suitable for occasions with different temperature measurement accuracy requirements.

The alcohol thermometer can measure low temperatures because it has a freezing point of -117, which can be used even in Antarctica, the hottest city on Earth (the lowest temperature on the Earth's surface). Mercury is different, it solidifies at -39. After the mercury solidifies, it loses its fluidity, and even if the surrounding temperature continues to drop, the mercury can no longer indicate the temperature.

In some places in the northeast of China, the temperature in winter is often -40, so it is only suitable to use alcohol thermometers in these colder places.

However, alcohol also has the great disadvantage that it takes much more calories than mercury to raise the temperature of the same weight of alcohol and mercury1. The amount of heat that raises (or decreases)1 alcohol can raise (or decrease) mercury by about 20. For the same temperature changes, a mercury thermometer is much more sensitive than an alcohol thermometer.

Therefore, mercury thermometers are generally used in scientific experiments or when measuring human body temperature. Another advantage of a mercury thermometer is that it can be used to measure high temperatures, as it has a boiling point of up to 357.

Of course, there is another disadvantage of mercury thermometers: during use, once the thermometer is accidentally broken, the mercury inside leaks, and the liquid mercury will volatilize into the air and cause harm to the human body.

Alcohol, kerosene, mercury and so on Standards: all monotonous and significant changes occur with the change of temperature Difference: The sensitivity of different thermometers of liquids is different, because the expansion coefficient of liquids is different, and the general thermometer uses mercury; Alcohol for thermometers for household cold and summer meters; Kerosene is generally used in the laboratory.

To put it simply: the chemical reaction of wood during the heating process precedes the change of physical state.

Specific answer: The change of state of matter in secondary school refers to:

Melting: Solid liquid state.

Coagulation: Liquid solid.

Vaporization: Liquid gaseous.

Liquefaction: Gaseous liquid state.

Sublimation: Solid gaseous state.

Condensation: Gaseous solid.

Therefore, not all solids will become liquid as soon as they are heated, and some will directly turn into gases, such as iodine.

As for your supplemental question, heating wood, wood is organic matter, chemical properties are flammable, once the heating has not had time to occur biological changes, chemical changes will occur, so the phenomenon we see when heating wood is not a physical change of matter, but a chemical reaction, so can wood be liquefied or sublimated? It is uncertain that the reason is how to control the chemical response of the wood during the heating process, and to what temperature it should be heated? No one has done anything about it.

In short, you can think of it this way: the chemical reaction of wood during heating precedes the change of physical state.

Does the change of state of matter mean that solids can be turned into liquids when heated? Question added:

But why is wood, for example, scorched when heated, and not turned into liquid or gas?

These are two different problems, the first is a physical problem, the latter is a chemical problem, and the latter one is not a change in the state of matter.

The so-called change of state of matter means that the same substance changes between solid, liquid and gas, rather than other substances.

Crystals have to reach the melting point, and amorphous crystals depend on the temperature, and if you burn glass, you use 10,000 degrees Celsius to melt it, and if you burn it at one degree Celsius, it won't melt for tens of thousands of years.

Wood one, wait for high school to synthesize physics and chemistry, and then reorganize.

We can't figure it out in junior high school.

Do you want to burn it, is it carbonized, carbon can't be liquefied?

Hehe.. No, solid-liquid gas is said for the most part. It's like water or something.

But the wood you said doesn't really turn into liquid, but at a certain temperature, it can be begged to beg... It's sublimation. Hehe..

In fact, there are things that can be sublimated at a certain temperature. Remember that the premise is that the temperature reaches ... Roar.

Study hard.

There is some truth to what is said upstairs about crystals.。。。 Hehe..

Not all of the substances that are heated directly into a gaseous state, such as iodine.

Wood is a mixture, moisture and air cause you to draw the wrong conclusion.

The amount of heat absorbed by cold water is equal to the amount of heat emitted by hot water.

That is, q sucks = q puts.

C water m cold (t end - t cold beginning) = c water m heat (t hot first - t end) 2kg * (t end - 20) = 1kg * (80 - t end) t end = 40

These water droplets are the result of condensation of water vapor when it meets with water.

Due to the high temperature of the water in the bath, the water in the bath evaporates relatively quickly, so there are a lot of colorless and odorless water vapor above the bath, which is not visible to people;

When the water vapor floats upwards and encounters a relatively cold ceiling, the water vapor temperature will drop, causing the water vapor to condense into small water droplets;

As for why the size of the water droplets is the same, the result of the combination of the gravity of the water droplets and the adsorption force of the water droplets on the ceiling: when the water droplets condense into larger water droplets, the water droplets will fall; When the water droplets are not as big as the ceiling, the adsorption force of the water droplets is greater than the gravity, so the water droplets can continue to grow. That's why the water droplets are almost the same size.

Hope it can help you

When the hotter water meets the colder ceiling, it will release heat and liquefy into small water droplets attached to the flowering board, and the more they gather, the more they will become large water droplets.

This is because hot water vapor is generated during bathing, and when it hits the ceiling (when it is cold), it liquefies into small droplets.