Physics problems in the second year of junior high school, the problem of physical state change in t

In winter, freshly washed clothes, carrying a lot of water, the temperature is higher than the outdoor temperature, when the clothes are taken outside to dry, the water will indeed vaporize into water vapor, this process does happen, but the eyes can't see it, because the water vapor can't see. (e.g., there is a lot of water vapor in the air around us right now, at any time, but we can't see it).

When we see "white gas", it is a small water droplet formed by the liquefaction of water vapor when it encounters a low temperature environment outside.

Therefore, the "white gas" that is "seen" is liquefied.

The full version is that water first vaporizes into water vapor, which then liquefies into small water droplets.

Hello! The phenomenon you mentioned is: in winter, washing clothes indoors with warm water, taking them to dry outside, and seeing "white gas" from clothes, the phenomenon is liquefaction, which is due to the evaporation of water vapor, which liquefies into small droplets when encountering the surrounding cold air, so we see "white gas" from clothes.

Please note: The vaporization of water is from liquid water to gaseous water vapor, and water vapor is colorless and cannot be seen by humans.

I hope it helps you, and if you have any questions, you can ask them

I wish you progress in your studies and go to the next level! (*

After the clothes are washed, they are wet, the water is constantly evaporating, this process is vaporization, and we can't see anything. When the clothes are taken outside, the outdoor temperature is relatively low, and the vaporized water vapor becomes small water droplets when cold, which are suspended in the air because the water droplets are very small. So what we're seeing is white gas.

The process by which water vapor turns into small water droplets is liquefaction.

Liquefaction: The process by which an object changes directly from a gas to a liquid.

Vaporization: The process by which an object changes directly from a liquid to a gas.

In winter, the washed clothes are taken outside to dry, the outdoor temperature is low, and when the clothes are encountered, the water vapor in the air will liquefy into small liquid droplets, which is the "white gas" you see. It is the process of liquefaction.

Think about what other physical phenomena are related to the change of state of matter in the home kitchen, and explain these phenomena Test point: liquefaction and liquefaction phenomenon; solidification and solidification exothermic characteristics; characteristics of vaporization and vaporization endothermy; The phenomenon of sublimation in life Topic: Answer open-ended Analysis:

We can analyze the heating appliances in the kitchen--- induction cookers and gas stoves, and refrigerators that reduce the temperature Answer: Answer: When boiling water, a puff of "white gas" will come out when the lid of the pot is lifted

This is formed by the liquefaction of a large amount of water vapor coming out when cold

When you take the mineral water out of the refrigerator, after a while small droplets appear on the walls of the bottle: this is formed by the liquefaction of water vapor in the air when it is cold

The water in the freezer compartment of the refrigerator, after a period of time, will condense into ice: this is the phenomenon of coagulation Comments: This question is to let us find the phenomenon of change in the state of matter from life This requires us to observe and think more in life

Detailed explanation:

1. Select A for the first question

Explanation: The apple has just been taken out of the refrigerator, and the water vapor in the air is liquefied into small water droplets, so it is wet first, and then the small water droplets evaporate after a while, so choose A, the landlord should think like this when he sees such a problem, you see, because the title says that it is wet first, so it is said that the object eventually becomes liquid, and the initial state is gaseous, so it is liquefied first, in the same way, and then dried out from liquid to gaseous, so it is vaporization (evaporation).

2. Vaporization (or evaporation): Because it is turned into water vapor by water, it is vaporization.

Liquefaction: It is liquefaction because the gas becomes liquid again.

3. Sublimation and condensation.

Explanation: The filament becomes gaseous when heated, so the filament will become thinner, which is sublimation, and then the gaseous state meets the glass wall and quickly condenses into black ash when cold, and becomes solid from gas, so it is condensation.

4. Coagulation: Wet clothes originally contain liquid, and the freezing becomes solid, and the liquid state changes to solid solid.

Sublimation: Frozen clothes contain solid (ice), and when dried, it means that it becomes gaseous, and from solid to gaseous state belongs to sublimation.

The degree of ice is constant: at the freezing point of temperature, exothermic, ice is crystalline, and the temperature does not change.

Water at 0 degrees is unchanged: water at 0 degrees Celsius will solidify when it is exothermic, and during the solidification process, the temperature will not change, because the ice that becomes is crystals.

Ice-water mixture: unchanged.

an increase in ice temperature of 10 degrees;

Water of 30 degrees Celsius is lower.

Short answer: 1, a

2. Vaporization and liquefaction.

3. Sublimation and condensation.

4. Solidification and sublimation.

5. Unchanged, unchanged, unchanged, elevated, decreased.

1.First wet vapor liquid (exothermic) liquid.

After dry liquid vapor (endothermic) gaseous state.

2.Vaporization of the liquid vapor state (endothermic).

Vapor liquid (exothermic) liquefaction.

3.Vapor solid (exothermic) condensation.

Solid vapor (endothermic) sublimation.

4.Liquid solids (exothermic) solidification.

Solid vapor (endothermic) sublimation.

5.No change. No change, no change.

Lower: Lower: Lower.

。Vaporization Liquefaction.

3.Sublimation, condensation.

4.Solidification sublimation.

5.No change, no change, no change, no change, decrease.

, evaporation, condensation.

3.Sublimation. 4.Condensation, sublimation.

Degrees of ice Drop 0 degrees of water Ice-water mixture Unchanged -10 degrees of ice and 30 degrees of water decrease.

1a 2 evaporation liquefaction 3 sublimation liquefaction 4 solidification sublimation 5 unchanged decreased.

1a 2 evaporation, liquefaction 3 sublimation, condensation 4 coagulation, sublimation 5 elevation, elevation, elevation, elevation, elevation.

The division value of this thermometer r (the temperature difference represented by 1 division) = 100 (94-4) = (10 9).

A 67 indicator is higher than a 4 indicator (67-4) = 63 divisions.

The actual temperature t=(10 9)*63=70

The graduation value of this thermometer is 100 (94-4) = (10 9).

A 67 indicator is higher than a 4 indicator (67-4) = 63 divisions.

The actual temperature t=(10 9)*63=70

The scale 4 and scale 94 on this thermometer represent the actual 0 and 100, respectively, so divide the distance between them by 100 (94 -4) 100=, i.e. the actual 1 on this thermometer (understand?). ）

So t(actual) = (67 -4).

1.White gas is a small water droplet formed by air condensation, which is denser than air, so it floats downward.

2.It dissolves and absorbs heat as it passes through the atmosphere, maintaining the temperature in the cabin.

3.Same as 1, because the drink has just been taken out, the temperature is lower than the air, and it condenses into small water droplets attached to the wall of the cup.

1. Liquefaction phenomenon: The density of cold air is high.

2. Paint vaporization absorbs heat.

3. Water vapor liquefies when cold.

(vaporized), (ventilated).

Vaporization --- change of a substance from a liquid state to a gaseous state is called vaporization. There are two different ways of vaporization: evaporation and boiling. Both methods are endothermic.

The water on the surface of the teapot is constantly evaporating, which is one of the ways of vaporization (evaporation), which absorbs the heat from the teapot and the inside of the teapot, and the water in the teapot becomes cooler.

The conditions that affect evaporation are: The temperature of the liquid The surface area of the liquid The flow of air on the surface of the liquid.

So it should be placed in a ventilated place.