Kinetic Theory – states of matter, solids, liquids, gases
Demonstrate the relationship between kinetic energy and molecular speed. Theory of Gases” shows a representation of how we mentally picture the gas phase. The kinetic molecular theory of gases describes this state of matter as. Substances can change from one state to another. Kinetic theory can explain the change of state by considering all matter (substances) to be made of particles. kinetic molecular theory: Theory of treating samples of matter as a large . and States of Matter: Explore how states of matter are related to the strength of.
As she gets closer to the surface of the water, the air bubbles get bigger. The pressure of the water decreases as the diver gets closer to the surface. Because the bubbles are under less pressure, they increase in volume even though the amount of gas in the bubbles remains the same. Gas bubbles get bigger when they are under less pressure.
States of Matter (Book)
What happens when a gas is heated? Its particles gain energy. With more energy, the particles have a greater speed.
Therefore, they can move more and spread out farther. The volume of the gas increases as it expands and takes up more space. The graph in Figure below shows this relationship between the temperature and volume of a gas.
As the temperature of a gas increases, its volume also increases. Roger had a latex balloon full of air inside his air-conditioned house. When he took the balloon outside in the hot sun, it got bigger and bigger until it popped. As the gas in the balloon warmed in the sun, its volume increased.
It stretched and expanded the latex of the balloon until the balloon burst. A heated gas has more energy. Its particles move more and have more collisions, so the pressure of the gas increases.Phase Changes
The graph in Figure below shows this relationship. As the temperature of a gas increases, its pressure increases as well. A woman checked the air pressure in her tires before driving her car on a cold day see Figure below. The tire pressure gauge registered 32 pounds of pressure per square inch.
After driving the car several miles on the highway, the woman stopped and checked the tire pressure again. This time the gauge registered 34 pounds per square inch.
As the tires rolled over the road, they got warmer. The air inside the tires also warmed. As it did, its pressure increased. A tire pressure gauge measures the pressure of the air inside a car tire. Why is the pressure likely to increase as the car is driven? Lesson Summary Particles of a gas are constantly moving and bumping into things. This gives gases pressure. The gas laws describe the relationship among pressure, volume, and temperature of a given amount of gas.
Changes of State Introduction Matter is always changing state. Look at the two pictures of Mount Rushmore in Figure below.
The picture on the left was taken on a sunny summer morning. In this picture, the sky is perfectly clear. The picture on the right was taken just a few hours later. In this picture, there are clouds in the sky. The clouds consist of tiny droplets of liquid water. Where did the water come from? It was there all along in the form of invisible water vapor. Both of these pictures of Mount Rushmore were taken on the same day just a few hours apart.
This is because the smoke particles show up by reflected light and 'dance' due to the millions of random hits from the fast moving air molecules. This is called 'Brownian motion' see below in liquids.
At any given instant of time, the particle hits will not be evenly distributed over the surface, so the smoke particle get a greater bashing in a random direction and then another, so they appear to dance and zig-zag around at random. A two gaseous molecule diffusion experiment is illustrated above and explained below! A long glass tube 2—4 cm diameter is filled at one end with a plug of cotton wool soaked in conc. A similar plug of conc. The soaked cotton wool plugs will give off fumes of HCl and NH3 respectively, and if the tube is left undisturbed and horizontal, despite the lack of tube movement, e.
What happens is the colourless gases, ammonia and hydrogen chloride, diffuse down the tube and react to form fine white crystals of the salt ammonium chloride. The smaller the molecular mass, the greater the average speed of the molecules but all gases have the same average kinetic energy at the same temperature. Therefore the smaller the molecular mass, the faster the gas diffuses.
For a mathematical treatment see Graham's Law of Diffusion A coloured gasheavier than air greater densityis put into the bottom gas jar and a second gas jar of lower density colourless air is placed over it separated with a glass cover. Diffusion experiments should be enclosed at constant temperature to minimise disturbance by convection.
How does kinetic energy relate to the states of matter? | Socratic
If the glass cover is removed then i the colourless air gases diffuses down into the coloured brown gas and ii bromine diffuses up into the air. The random particle movement leading to mixing cannot be due to convection because the more dense gas starts at the bottom! No 'shaking' or other means of mixing is required. The random movement of both lots of particles is enough to ensure that both gases eventually become completely mixed by diffusion spread into each other.
Kinetic Molecular Theory ( Read ) | Chemistry | CK Foundation
This is clear evidence for diffusion due to the random continuous movement of all the gas particles and, initially, the net movement of one type of particle from a higher to a lower concentration 'down a diffusion gradient'.
When fully mixed, no further colour change distribution is observed BUT the random particle movement continues! See also other evidence in the liquid section after the particle model for diffusion diagram below. A particle model of diffusion in gases: Imagine the diffusion gradient from left to right for the green particles added to the blue particles on the left. So, for the green particles, net migration is from left to right and will continue, in a sealed container, until all the particles are evenly distributed in the gas container as pictured.
Heat energy is transferred by 'hotter' higher kinetic energy gas particles colliding with 'cooler' lower kinetic energy particles so raising their kinetic energy and spreading the heat energy. However, the density of gases is very low, so the density or rate of 'collision transfer' is quite low.
Therefore gases are very good insulators e.
Gases are poor conductors of electricity because they are usually not in an ionic or ionised form. However, applying a very high potential difference of thousands of volts, especially with a low gas pressure, can cause the formation of free ions and electrons and electrical conduction can happen. Strip lighting and neon signs use this effect.
A note on 'forces' Forces between particles are mentioned on this page and some ideas will seem more abstract than others — but think about it Something must hold liquid molecules together or how can a liquid form from a gas? In fact between liquid molecules there are actually weak electrical forces of attraction called intermolecular forces, but they can't be strong enough to create a rigid solid structure.
However, in solids, these forces must be stronger to create the rigid structure. Intermolecular forces are also called 'intermolecular bonds' BUT these are not the same as covalent, ionic or metallic bonds and they are much weaker than these true chemical bonds. How does the kinetic particle theory of liquids explain the properties of liquids? A liquid has a fixed volume at a given temperature but its shape is that of the container which holds the liquid. There are m uch greater forces of attraction between the particles in a liquid compared to gases, but not quite as much as in solids and the particles are sufficiently free to move past each other.
If there were no intermolecular forces, liquids could not exist! The particles are quite close together but still arranged at random throughout the container due to their random movement, there is a little close range order as you can get clumps of particles clinging together temporarily as in the diagram above. The p articles are moving rapidly in all directions but collide more frequently with each other than in gases due to shorter distances between particles — much greater density.
With increase in temperature, the particles move faster as they gain kinetic energy, so increased collision rates, increased collision energy, increased rates of particle diffusion, expansion leading to decrease in density. Most liquids are just a little less dense than when they are solid Water is a curious exception to this general rule, which is why ice floats on water. Note 'sticky' or viscous liquids have much stronger attractive forces between the molecules BUT not strong enough to form a solid.
Liquids have a surface, and a fixed volume at a particular temperature because of the increased particle attraction, but the shape is not fixed and is merely that of the container itself. Liquids seem to have a very weak 'skin' surface effect which is caused by the bulk molecules attracting the surface molecules disproportionately.
- Kinetic particle theory and state changes
- How does kinetic energy relate to the states of matter?