Liquids+and+Solids+from+the+kinetic-molecular+viewpoint

**The Kinetic Molecular Viewpoint (or Theory)**
====The Kinetic Molecular Viewpoint is a set of assmptions about the nature of gases and it is a theory of moving molecules. This viewpoint explains gas pressure, effusion and diffusion rates, and the effect of temperature on the behavior of gases. This viewpoint serves as a model to to many different types of scientists. Although this theory is very important to scientists today, it took over 100 years for it to be accepted by the scientific community when it was first introduced. This theory was first developed around 1743, by Daniel Bournelli. Together, James Clerk Maxwell and Ludwig Boltzmann convinced the other scientists that Bournelli's ideas were actually correct. Rudolf Clauius finally compiled the information and published a complete form of the theory in 1857. ====



 * 1) Gases consist of large numbers of moleculees, the smallest particle of any gas, that are in continuous, random motion.
 * 2) The combined volume of all the molecules of the gas is tiny compared to the total volume in which the gas is contained.
 * 3) Attractive and repulsive forces between the gas molecules are small.
 * 4) 4. During collisions energy can be transferred between the molecules, but the over time the average kinetic energy of the molecule does not change as long as the temperature of the gas stays the same. This means that the collisions between the gas molecules are elastic.
 * 5) The average kinetic energy of the molecules is proportional to the Kelvin temperature of the gas. This means that at any time the molecules of all gases have the same average kinetic energy.


 * The characteristics of the properties of these states of matter are defined in terms of the energy of motion, also known as the kinetic energy of the particles compared to the intermoleculer forces between the particles.
 * The second explanation of each state of matter describes the molecular comparision each state of matter.

====**Gases:** Gases are not as dense as neither liquids or solids. The particles in a gas are extremely spread out. This means that there is a lot of free space for the molecules to move around. The particles have no particular arrangement. The particles vibrate and move at very high speeds. ==== Below is a microscopic view of the molecules of a gas.

- Effusion is when molecules of gas escape from their container. **Graham's Law of Effusion** allows you to calculate the rate at which molecules of two gases escape from their containers:

http://bouman.chem.georgetown.edu/general/charles2/IMG00005.GIF

r = rate M = Molecular weight of the gases

====**Liquids:** Liquids are states of matter that assume the shape of the container that it occupies. Although a liquid does take its container's shape, liquids never expand to fill the container. When a liquid is poured, it flows readily. ==== ====The intermolecular forces in a liquid hold the molecules close together. This causes liquids to be much denser, but less compressible than gases. The forces in a liquid are not strong enough to stop the molecules from moving past one another. Therefore, the paricles are free to move past one another, even though the particles are close together. The particles vibrate, move about, and slide past each other. This allows any liquid to be able to be poured. It also allows it to assume the shape of any container that it is poured into. ==== The characteristics above are shown in the microscopic view of the molecules of a liquid below: [] ====**Solids:** Solids are much more dense than gases. Solids are states of matter that retain their own shape and volume. Solids never take the shape of their container. Therefore, solids do not flow. Like liquids, solids are also virtually incompressible. A solid does not flow easily. Diffusion within a solid occurs extremely slowly. ==== ====The intermolecular forces in a solid are so strong that they lock the molecules in place. Since the molecules are locked together, there is little to no free space between them. This causes solids to be almost impossible to be compressed. Solids, and liquids, are considered condensed phases because the particles are so much closer together than that of a gas. Solids are often referred to as having a "crystalline" structure because their arrangements are orderly. Solids are also rigid because the particles do not undergo much movement. Although the molecules of a solid do not move very much, the molecules do vibrate in place. The rigid arrangement of a solid does not allow it to flow easily. This slight vibrational movement increases in amplitude as the solid is heated. ==== <span style="font-family: Arial,Helvetica,sans-serif;">The characteristics above are shown in the microscopic view of the molecules of a solid below: [] The picture below shows how the comparision between pressure and temperature affects the phases of matter. Since both pressure and temperature affect the molecules of the state of matter, pressure and temperature also affect the specific state of matter that the molecules create.
 * Transformation Between Solids and Liquids**
 * "The state of a substance depends largely on the balance between the kinetic energies of the particles and the interparticle energies of attraction." (Chemistry: The Central Science Tenth Edition Pearson)
 * What this means is basically that the kinetic energies largely depend on temperature. The temperature keeps the particles apart and moving, causing more free space between the molecules.
 * Interparticle attractions draw the particles together causing the change between states of matter.
 * A gas has weaker interparticle forces allowing more free space between molecules.
 * A liquid has a stronger interparticle forces which allows the molecules to be pulled closer together but also to move past one another.
 * A solid has strong interparticle forces which allows the molecules to be pulled closely and tightly together into a rigid, uniform structure.
 * When the temperature of a gas decreases the average kinetic energy decreases.
 * During this process first the particles are drawn close together to form a liquid and then the particles are locked into place to form a solid.
 * Solids have high pressure, to push the molecules together, and a lack of heat energy. When the pressure decreases, or the heat energy increases a solid turns to a liquid.
 * A liquid has just enough energy to allow the molecules to move around each other. If the heat dramatically increases or the pressure decreases the liquid turns to a gas.
 * A gas has a large amount of heat energy but a very small amound of pressure.
 * Don't Understand the Transformation?**
 * Think of taking a shower.
 * When you shower the water molecules become so hot that their "bonds" break. When you come out of the shower the water molecules have broken and the hot "gas" is now filling your bathroom. Once the gas molecules bump into the cool mirror, the temperature decreases again and the gas condenses back into a liquid.
 * This is just one example of the phase transformation from a liquid to a gas.

This picture shows the molecular level comparision between a solid, liquid, and gas in a container. It allows the comparision to be more visible when the molecular level is show in relation to an enclosed space. [|http://sol.sci.uop.edu/~jfalward/specificandlatentheats/threephasesinajar.jpg]

A: The molecules in a gas are farther apart than those in a liquid. The molecules in a gas move more freely and bump into each other more often. The molecules of a liquid are more tightly packed but still move around. The more empty space between the gas particles allows the to be more compressible.
 * Let's See If You Remember!**
 * 1) **Why are gases more compressible than liquids?**

A: This question refers back to the kinetic molecular theory. The average kinetic energyof a liquid is on the same order of magnitude as the average attractive energy among particles. This allows liquids to have a greater ability to flow.
 * 2. Why do liquids have a greater ability to flow than solids?**

A: Liquids and solids are called condensed phases because the molecules have little to no free space between their paricles. Chemistry: The Central Science. Pearson Barron's AP Chemistry 2008 4th Edition. [] [] []
 * 3. Why are liquids and solids called condensed phases?**
 * Sources:**