This video explores the process of evaporation and the an interpretation of temperature. It have the right to be provided as a supplement to an investigation, or may stand on its very own to present a great or expand student learning.

You are watching: The average kinetic energy of all the particles in a material


Ah, the humble thermometer. Whether we desire to understand if our vacation turkey is cooked or if we require concrete proof that we’re also sick to attend school, a thermometer is the precise scientific tool we need. Yet what, exactly, does a thermometer measure? In various other words, what is temperature, really?


Whether the solid, liquid, or gas, all matter is made up of atoms and also molecules. These particles room constantly in motion. Castle collide through each other and with the wall surfaces of anything they are included in. We quantify the movements of the particles by your kinetic energies.

In chemistry, we define the temperature of a substance together the median kinetic energy of all the atom or molecules of the substance.

Not all of the particles of a substance have actually the very same kinetic energy. At any type of given time, the kinetic energy of the particles can be stood for by a distribution. Some atoms or molecules have actually a many kinetic energy and move very fast. Other atoms or molecules have actually a little kinetic energy and move very slowly. That is the typical kinetic power of the particles the thermometers measure and also we document as the temperature.

One procedure that illustrates differing kinetic energies particularly well is evaporation. Together you probably know, evaporation is a phase change where corpuscle of a substance move from the fluid phase right into the gas phase.

But have actually you ever wondered exactly how a puddle of water deserve to evaporate in ~ room temperature? store that in mind—we’ll come ago to that inquiry in a bit.


When we think about a phase adjust from liquid to gas, we regularly think about adding thermal energy to a liquid by heating it up. As soon as we do, the molecule of the liquid relocate faster and spread contempt farther apart, till they acquire enough power to conquer the attractions they have for other molecules of the liquid and enter the gas phase.

Think about this: If who asked girlfriend to rotate a beaker full of water right into water vapor, what would you do?

Being the brilliant young scientist the you are, you can put the on a hot plate and crank up the heat. Now you have the right to kick back and relax till the hot plate transfers enough energy to acquire all the water molecule to shift from the liquid phase to the gas phase. In less science-y terms, you would boil the water.

Boiling is a special instance of a liquid-to-gas phase change that wake up at a specific temperature referred to as the boiling point, where the vapor pressure of the substance is same to one atmosphere pressure. Boil is usually carried out utilizing a continuous input of energy from an external source (like a warm plate) to store the temperature constant.

The evident conclusion is this: If you continuously include thermal energy from a hot plate friend can reason a phase adjust from fluid to gas.

But how deserve to a puddle of water evaporate in ~ room temperature?

When water evaporates in ~ room temperature, part fast-moving, very energetic molecules have enough power to get over the attractions the individual molecules have actually for one another and also enter the gas phase. As these high-energy molecules leave the fluid phase, the average energy of the continuing to be liquid molecule is lowered, and also their temperature decreases. This liquid is in ~ a lower power than that is surroundings, so the absorbs energy from those surroundings. The cycle continues as the puddle gradually disappears.

Boiling is a faster procedure because the next site (the warm plate) warmth the fluid to a greater temperature where much more molecules have high energy, so vaporization is faster. The hot plate is hotter 보다 the liquid, for this reason thermal energy transfer is fast sufficient to store the liquid temperature continuous at the boil temperature.

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Evaporation have the right to take place at any kind of temperature because some the the molecule in a liquid—the ones at the higher end of the distribution—will always have enough energy to get in the gas phase. Chris

To sum up, temperature represents the median kinetic power of the particles of substance. Yet it’s the spread of kinetic energies among the individual corpuscle that describes why puddles dried up.