Kinetic Theory of Matter ( Read ) | Physical Science | CK Foundation
posavski-obzor.info header image. Kinetic Theory. There are three states of matter;. solid, liquid and gas. Substances can change from one state to another. Kinetic theory can explain the change of state by considering all matter changing state. PhysicsNet Site Search. Links. Careers · University Physics Courses · Why take. 3 Why different states? Matter exists in several different states due to the amount of KINETIC ENERGY its particles have. Matter exists in several different states. There are five known phases, or states, of matter: solids, liquids, gases, plasma The main difference in the structures of each state is in the densities of the particles. Gas particles have enough kinetic energy to overcome.
Physical Properties of Liquids In a gas, the distance between molecules, whether monatomic or polyatomic, is very large compared with the size of the molecules; thus gases have a low density and are highly compressible. In contrast, the molecules in liquids are very close together, with essentially no empty space between them.
As in gases, however, the molecules in liquids are in constant motion, and their kinetic energy and hence their speed depends on their temperature.
- Kinetic Theory
- What happens to the kinetic energy of its molecules as ice melts into water?
- 11.1: A Molecular Comparison of Gases, Liquids, and Solids
We begin our discussion by examining some of the characteristic properties of liquids to see how each is consistent with a modified kinetic molecular description.
The properties of liquids can be explained using a modified version of the kinetic molecular theory of gases described previously This model explains the higher density, greater order, and lower compressibility of liquids versus gases; the thermal expansion of liquids; why they diffuse; and why they adopt the shape but not the volume of their containers.
A kinetic molecular description of liquids must take into account both the nonzero volumes of particles and the presence of strong intermolecular attractive forces.
How does kinetic energy relate to the states of matter?
Solids and liquids have particles that are fairly close to one another, and are thus called "condensed phases" to distinguish them from gases Density: The molecules of a liquid are packed relatively close together.
Consequently, liquids are much denser than gases. The density of a liquid is typically about the same as the density of the solid state of the substance.
As the liquid is cooled, particle motion slows. In many substances, the particles align in precise, geometric patterns to form crystalline solids. Most liquids contract as they freeze. One of the important characteristics of water is that it expands when it freezes, so ice floats.
Matter: Definition & the Five States of Matter
The freezing point is often nearly the same temperature as the melting point, but is not considered to be characteristic of a substance, as several factors can alter it. For example, adding dissolved substances, or solutes, to a liquid will depress the freezing point. An example of this is using salt slurry to lower the temperature at which water freezes on our roads.
Other liquids can be cooled to temperatures well below their melting point before they begin to solidify. Sublimation When a solid is converted directly into a gas without going through a liquid phase, the process is known as sublimation. Sublimation occurs when kinetic energy of the particles is greater than atmospheric pressure surrounding the sample.
This may occur when the temperature of the sample is rapidly increased beyond the boiling point flash vaporization. More commonly, a substance can be "freeze dried" by cooling it under vacuum conditions so that the water in the substance undergoes sublimation and is removed from the sample. A few volatile substances will undergo sublimation at normal temperature and pressure.
Vaporization can occur through either evaporation or boiling. Because the particles of a liquid are in constant motion they frequently collide with each other, transferring energy when they do so.
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This energy transference has little net effect beneath the surface, but when enough energy is transferred to a particle near the surface; it may gain enough energy to be knocked completely away from the sample as a free gas particle. This process is called evaporation and it continues as long as liquid remains. It is interesting to note that a liquid cools as it evaporates. The energy transferred to surface molecules, which causes their escape, is carried away from the remaining liquid sample.
When enough heat is added to a liquid that vapor bubbles form below the surface of the liquid, we say that the liquid is boiling. The temperature at which a liquid boils is variable. Boiling point is dependent upon the pressure the substance is under. A liquid under higher pressure will require more heat before vapor bubbles can form within it. At high altitudes, there is less atmospheric pressure pressing down on the liquid, so it will boil at a lower temperature. The same amount of liquid at sea level is under a greater atmospheric pressure and will boil at a higher temperature.
Condensation and deposition Condensation is when a gas transforms into a liquid. Condensation occurs when a gas has been cooled or compressed to the point where kinetic energy of the particles can no longer overcome the intermolecular forces. An initial cluster of particles initiates the process which tends to further cool the gas so that condensation continues.
6(c). Energy, Temperature, and Heat
When the gas transforms directly into a solid, without going through the liquid phase, it is called deposition or desublimation. Sensible Heat - is heat that we can sense.
A thermometer can be used to measure this form of heat. Several different scales of measurement exist for measuring sensible heat.
The most common are: Celsius scaleFahrenheit scaleand the Kelvin scale. Latent Heat - is the energy needed to change a substance to a higher state of matter.
This same energy is released from the substance when the change of state or phase is reversed. The diagram below describes the various exchanges of heat involved with 1 gram of water. Latent heat exchanges of energy involved with the phase changes of water. Figures 6c-2 and 6c-3 show the net absorption and release of latent heat energy for the Earth's surface for January and July, respectively.
The highest values of flux or flow occur near the subtropical oceans where high temperatures and a plentiful supply of water encourage the evaporation of water.