Please design an experiment to show whether evaporation is endothermic or not

In many cases, evaporation occurs without heating, but evaporation is affected by many factors, one of which is related to the temperature. The higher the temperature, the faster the evaporation. No matter what the temperature, there are always some molecules in the liquid with a high velocity that can fly out of the liquid surface and become vapor molecules, so the liquid can evaporate at any temperature.

If the temperature of the liquid increases, the average kinetic energy of the molecules increases, and the number of molecules flying out of the liquid surface increases, so the higher the temperature of the liquid, the faster the evaporation;

The second is related to the size of the liquid surface area. If the surface area of the liquid increases, the number of molecules near the surface of the liquid increases, so that in the same time, the number of molecules flying out of the liquid surface increases, so the liquid surface area increases, and the evaporation accelerates;

The third is related to air flow. When vapor molecules flying into the air collide with air molecules or other vapor molecules, they may be bumped back into the liquid. If the liquid surface air flows quickly and is well ventilated, the less chance the molecules will return to the liquid, the faster the evaporation.

When you apply alcohol to your hands, it is very cold, indicating that the alcohol has evaporated and absorbed heat; It is also possible to apply a thermometer.

Water is also available, but it is less noticeable.

Apply alcohol to your hands and your hands feel cold. Indicates that the alcohol absorbs heat as it evaporates.

In summer, water is sprinkled on the ground to cool down and absorb heat.

A lot, it's raining and it's cold, etc.

Alcohol is applied to your hands and the sensation is most noticeable.

Summary. Hello dear, I'm glad to answer for you, water evaporation will affect the temperature of the surrounding air, water evaporation absorbs heat, and it absorbs the heat of water that has not yet evaporated. Therefore, the temperature of the remaining water should be reduced.

This requires further heat transfer with the environment, so that the ambient temperature also drops. For example, if we sprinkle some water on the ground in the summer, we feel cool, and this is the reason.

Does water evaporation affect the ambient air temperature? Please design an experiment to prove it.

Hello dear, I'm glad to answer for you, water evaporation will affect the temperature of the surrounding air, water evaporation absorbs heat, and it absorbs the heat of water that has not yet evaporated. Therefore, the temperature of the remaining water should be reduced. This requires further heat transfer with the environment, so that the ambient temperature also drops.

For example, if we sprinkle some water on the ground in the summer, we feel cool, and this is the reason.

I hope the above is helpful to you If you are satisfied with me, please give me a thumbs up

Answer: In summer, when the ground is sprinkled with water, the water needs to absorb heat during the evaporation process, so the surrounding temperature will decrease;

When you are sick and have a fever, rub alcohol on your body (or put a wet towel on your body), and the alcohol (or water) evaporates to absorb the heat and cool the body

Answer: In summer, when the ground is sprinkled with water, the water needs to absorb heat during the evaporation process, so the surrounding temperature will decrease;

When you are sick and have a fever, rub alcohol on your body (or put a wet towel on your body), and the alcohol (or water) evaporates to absorb the heat and cool the body

Answer: When you are sick and have a fever, rub alcohol on your body (or put a wet towel on your body), and the alcohol (or water) will evaporate to absorb the heat and cool down your body

The liquid socks of the refrigerator evaporate and absorb heat, reducing the temperature and stuffiness in the refrigerator

Categories: Education, Science, >> Learning Aid.

Problem description: I wonder why a liquid absorbs heat from itself, is it possible?

Analysis: When the liquid evaporates, it should absorb heat from itself and the surrounding environment, so that the liquid and the surrounding environment are cooled down due to exothermy, and at the same time, the internal energy of the vapor formed by evaporation increases after heat absorption, so that the molecular movement is more intense! Therefore, instead of "liquid endothermy", it is "evaporative endothermy", and then the vapor takes away the heat it absorbs, which cools the liquid and the surrounding environment.

(1) Incorrect The same alcohol lamp heats up for the same time and absorbs the same amount of heat (2) B (3).

Analysis: (1) According to the image, a student thinks: "If you heat for the same time, A will raise the temperature higher, which means that A absorbs more heat" This student's judgment is incorrect: The reason is that the same alcohol lamp heats the same time and absorbs the same heat.

2) To raise A and B to the same temperature, B should be heated for a longer time.

3) If the specific heat capacity of A is known to be j (kg· ) Then the specific heat capacity of B is.

1. The volume of the liquid is the same

2. Use the same alcohol lamp to ensure that the two liquids absorb the same heat.

The rest is not pictured, and it is hard to say.

Evaporation can occur at any temperature, regardless of temperature. Evaporation only takes place on the surface of the liquid, and unlike boiling, boiling not only reaches the boiling point of the liquid, but also continuously absorbs heat in order to continue to vaporize. Vaporization is a drastic physical phenomenon that occurs inside and on the surface of a liquid!

The condition of evaporation is endothermy, not the temperature condition, endothermy means to absorb heat, as long as there is heat absorption, it can evaporate, please continue to ask if you don't understand.

The evaporation process is endothermic (refers to the evaporation process itself must absorb heat, otherwise it cannot evaporate), gaseous water contains more energy than liquid water (equal mass, equal temperature), so when liquid water becomes gaseous water, it must absorb energy from the outside world (endothermy), otherwise energy conservation cannot be achieved! (Just like a person who changes from a poor person to a rich person, although he is a person, but his state changes, the amount of money on his body changes, and the poor person must earn money from elsewhere (absorb heat) in order to become rich.) (If the body is wet, the wind will feel very cold, because the evaporation of water is accelerated, and this process absorbs heat from your body, it is the decrease in heat in your body, and the manifestation of a decrease in temperature, so it is cold).

It is true that the temperature of the water decreases because of exothermics, but to whom is this heat released, obviously it is released to the endothermic evaporation process, one endothermic and the other exothermic to ensure the conservation of energy (energy can neither disappear out of thin air nor be generated out of thin air).

The heat released is not only transferred to the evaporation process, but also to the air (hot water is hotter than air, and heat is always transferred from high temperature to low temperature) This is also an exothermic process.

As long as the energy contained in an object decreases, usually in the form of a decrease in temperature, it undergoes an exothermic process.

Experimental equipment: One flask with a rubber stopper.

A slender glass tube bent at right angles, red ink, alcohol and cotton balls Process: 1. Dig a hole in the rubber plug that fits the size of the slender glass tube.

2. Add red ink to the slender glass tube bent at right angles to become an ink column and keep it in the middle of the glass tube.

3. Insert the glass tube into the hole and plug it on the mouth of the flask.

4. Hold the wall of the flask with your hands and check whether there is air leakage. If Li Pintan is disturbed by the air leakage, after the red ink column is stabilized, it is smeared on the wall of the flask with cotton dipped in alcohol.

Phenomenon: The temperature of the gas in the flask decreases, the volume decreases, and the ink column moves in the direction of the mouth of the flask.

Conclusion: The alcohol evaporates, absorbing heat, resulting in a decrease in the temperature of the gas inside the flask

Equipment: Alcohol lamp, iron stand, beaker, temperature meter, water.

Process: Heat the water in the beaker with an alcohol lamp and observe the thermometer changes at regular intervals (the same interval time).

Observation phenomenon: the thermometer will change with time, and the temperature of the water will rise without breaking the reed, indicating that the liquid needs to absorb heat for heating. But when it reaches the boiling point, the boiling point temperature will remain unchanged.