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Sunday, 29 June 2014

Plasma and Bose-Einstein Condensate (BEC)

It all started when my teacher told me there are five states of matter.

We all know the three basic states of Matter: Solid, Liquid, and Gas. However, there are two other states: Plasma, and Bose-Einstein Condensate (BEC).


What are they?


First, I did the research on Plasma.


Plasma is like gases. However, the atoms are different, as they are made up of free electrons and ions of an element such as Neon (Ne). It is also made up of groups of positively and negatively charged particles. The particles are also free to move. There is practically no order, as compared to a gas.


Aurora Lights
Natural Plasmas do not occur very often. However, the Northern Lights and the Southern Lights, also known as aurora borealis and aurora australis respectively, is one example of Natural Plasma. It is caused by the collision of energetically charged particles with atoms at a high altitude within our atmosphere. Solar Winds that flow past Earth contains plasma particles which get pulled into the Earth's magnetic fields. Hence, aurora occurs both in the North and the South. Collisions also occur between the plasma particles, nitrogen, and oxygen atoms, releasing energy, which is the Northern and Southern Lights. 

Man-made Plasmas, however, happen in our surroundings. Take a look at the Fluorescent Light Bulbs placed in our homes. Inside these bulbs or tubes contain an inert gas, like argon. This gas is kept under low pressure, so that the plasma is easily formed. The electricity charges up the gas, which creates plasma. These uses lesser energy than Incandescent lamps, which is why it saves electricity.

Another example is the Plasma Ball. The Plasma Ball is actually made up of a coil of high current wires. The electrons, that is oscillating quickly, shakes the atoms, causing their electrons to fall of and form plasma. The Ball contains a partial vacuum, making it easier to make electric sparks that can be seen.

There are, of course, many other places where man-made plasma is found. Above are just a few examples.

Now, what about Bose-Einstein Condensate, also known as BEC for short?

Here is an video on Bose-Einstein Condensate.

Energy Change from BEC to Plasma


Bose-Einstein Condensate consists of unexcited and cold atoms, the exact opposite of that of Plasma. The state only happens at very low temperatures, within a few billionths of a degree from absolute zero. At that low temperature, the atoms have lost almost all energy. As such, they begin to clump. Since there is no more energy to transfer (as in solids or liquids), all of the atoms have exactly the same levels, like twins. The group of rubidium atoms sits in the same place, creating a "super atom".There are no longer thousands of separate atoms. They all take on the same qualities and become one blob.

Saturday, 21 June 2014

Classification of Matter, Kinetic Particle Theory, Brownian Motion and Diffusion

Matter. Everyone knows what is Matter. However, does everyone know the difference between the three different stages? Why does the solid have a definite volume and shape? Why does the gas have no definite shape and volume? These questions are some of the points being discussed in this blog post about matter.
Not only that, let us think about these: Why does pollen grains move in water? Why does the food colouring spread out in a bucket of water? All these will be explained in this post.

Firstly, let us state the simple knowledge everyone should know.

Matter is anything that has mass and occupies space.
All matter can exist in 3 physical states: solid, liquid & gas, depending on the temperature and pressure of their surroundings.
What are the differences among solids, liquids and gases?
  • A solid has a fixed shape and a fixed volume. It is not compressible.
  • A liquid has a fixed volume but it does not have a fixed shape. It can flow and takes the shape of its container. It is not compressible.
  • A gas has no shape, no surface and no fixed volume. It is highly compressible.
Let us look at the Model of the Three States of Matter:



Solid
Diagram
 
Arrangement of the particles
  1. Closely packed
  2. Regular pattern
Movement of the Particles
  1. Cannot move freely or move from place to place
  2. Vibrate
  3. Strong attractive forces




Liquid
Diagram

Arrangement

  1. Particles slightly further apart
  2. Random
Movement

  1. Particles slide past one another
  2. Free to move about .
  3. Have attractive forces between particles




Gas
Diagram
Arrangement

  1. Very far apart.  
  2. Randomly Arranged
  3. Takes up the space of the container
Movement

  1. Little attraction between them 
  2. Move about randomly at a very high speed.

That is how, in detail, we classify matter. Now let us go to the complicated topics. What is the Kinetic Particle Theory?


The Kinetic Particle Theory states that matter is made of a large number of tiny particles (atoms or molecules), which are in continuous and random motion.


The Kinetic Particle Theory could be proven by Brownian Motion and Diffusion. 

Brownian Motion, is the continuous and random motion of small solid particles in fluids (liquids and gases). Brownian motion had also proved the existence of particles that cannot be observed with a normal microscope.
Brownian Motion can be observed by placing smoke particles in air. The smoke particles, when seen under the microscope, can be seen to be moving.  If heat is supplied, the motion of the smoke particles become more vigorous. Brownian Motion can also be observed by placing pollen grains in water. The pollen grains's movement is caused by the bombardment by the water molecules.
Below is an Java applet. Using small particles as the particles of a gas or liquid, and a big particles as a small solid, the Brownian Motion can be shown. Also, watch the effect when the heat has been changed.

Gas Properties

Click to Run


Diffusion shows that particles move randomly from a region of high concentration to lower concentration.
If a bottle of perfume is opened in one corner of a room, we can smell it in another corner after a very short time as the perfume molecules have traveled from the bottle to your nose through the air. This spreading of molecules is called diffusion.

Bromine vapour can be used to show diffusion of gases. Bromine is a red brown liquid at room temperature. When it evaporates, it becomes a brown vapour. When a little bromine vapour is released into a vacuum, the brown vapour spreads through the vacuum almost at once, showing that the bromine molecules are moving at very high speed.

Diffusion of Bromine

If bromine vapour is released into a similar space full of air, the brown vapour still spreads quickly through the space but very much slower than in a vacuum. This is because the bromine molecules keep hitting the air molecules which get in the way. The air acts as a resistance.

The rate of diffusion of gases depends on the temperature and the density of the gases. The higher the temperature, the faster the diffusion, but the greater the density of the molecules, the slower the diffusion. Gases can also diffuse through walls which have pores slightly bigger than the size of the gas molecule.

Diffusion also takes place in liquids, though at a very much slower rate. An unstirred cup of coffee with milk will become uniformly coloured after many hours. In the school laboratory, diffusion of liquids can be shown using copper (II) sulfate solution and water as shown in the figure below. The two layers become uniformly mixed after a while.

Diffusion of Liquids