INTRODUCTION OF STATES OF MATTER

INTRODUCTION OF STATES OF MATTER

Observe different types of matter around you. What are its different states? We can see that matter around us exists in five different states–

i.    Solid state,

ii.   Liquid state

iii.  Gas state

iv.  Plasmastate

v.   Bose-Einstein Condensate.

These states of matter arise due to the variation in the characteristics of the particles of matter.

Now, let us study about the properties of these five states of matter in detail.

Questions

1.  The mass per unit volume of a substance is called density. (density = mass/volume).
Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water,chalk, cotton and iron.

2.   (a) Tabulate the differences in the characterisitcs of states of matter

      (b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

3.  Give reasons

     (a) A gas fills completely the vessel in which it is kept.
     (b) A gas exerts pressure on the walls of the container.
     (c) A wooden table should be called a solid.
     (d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

4.  Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

Source: This topic is taken from NCERT TEXTBOOK

THE SOLID STATE

THE SOLID STATE

Activity 1.9:

*   Collect the following articles— a pen, a book, a needle and a piece of wooden stick.

*   Sketch the shape of the above articles in your notebook by moving a pencil around them.

*   Do all these have a definite shape, distinct boundaries and a fixed volume? What happens if they are hammered, pulled or dropped?

*   Are these capable of diffusing into each other?

*   Try compressing them by applying force. Are you able to compress them?

All the above are examples of solids. We can observe that all these have a definite shape, distinct boundaries and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.

Consider the following:

*   What about a rubber band, can it change its shape on stretching? Is it a solid?

*   What about sugar and salt? When kept in different jars these take the shape of the jar. Are they solid?

*   What about a sponge? It is a solid yet we are able to compress it. Why?

All the above are solids as:

*   A rubber band changes shape under force and regains the same shape when the force is removed. If excessive force is applied, it breaks.

*   The shape of each individual sugar or salt crystal remains fixed, whether we take it in our hand, put it in a plate or in a jar.

*   A sponge has minute holes, in which air is trapped, when we press it, the air is expelled out and we are able to compress it

Source: This topic is taken from NCERT TEXTBOOK

THE LIQUID STATE

THE LIQUID STATE

Activity 1.10:

*   Collect the following:

         a. water, cooking oil, milk, juice, a cold drink.

         b. containers of different shapes. Put a 50 mL mark on these containers using a measuring cylinder from the laboratory.

*   What will happen if these liquids are spilt on the floor?

*   Measure 50 mL of any one liquid and transfer it into different containers one by one. Does the volume remain the same?

*   Does the shape of the liquid remain the same ?

*   When you pour the liquid from one container into another, does it flow easily?

We observe that liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.

Refer to activities 1.4 and 1.5

Activity 1.4: ( Diffusion of Particles )

*   Take two glasses/beakers filled with water.

*   Put a drop of blue or red ink slowly and carefully along the sides of the first beaker and honey in the same way in the second beaker.

*   Leave them undisturbed in your house or in a corner of the class.

*   Record your observations.

*   What do you observe immediately after adding the ink drop?

*   What do you observe immediately after adding a drop of honey?

*   How many hours or days does it take for the colour of ink to spread evenly throughout the water?

Activity 1.5: (Temperature effect on Diffusion )

*   Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water and another containing cold water. Do not stir the solution. Allow the crystals to settle at the bottom.

*   What do you observe just above the solid crystal in the glass?

*   What happens as time passes?

*   What does this suggest about the particles of solid and liquid?

*   Does the rate of mixing change with temperature? Why and how?

Where we saw that solids and liquids can diffuse into liquids. The gases from the atmosphere diffuse and dissolve in water. These gases, especially oxygen and carbon dioxide, are essential for the survival of aquatic animals and plants.

All living creatures need to breathe for survival. The aquatic animals can breathe underwater due to the presence of dissolved oxygen in the water. Thus, we may conclude that solids, liquids and gases can diffuse into liquids. The rate of diffusion of liquids is higher than that of solids. This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid-state.

Source: This topic is taken from NCERT TEXTBOOK

THE GASEOUS STATE

THE GASEOUS STATE

Have you ever observed a balloon seller filling a large number of balloons from a single cylinder of gas? Enquire from him how many balloons is he able to fill from one cylinder. Ask him which gas does he have in the cylinder.

Activity 1.11: ( compressibility of gases )

*   Take three 100 mL syringes and close their nozzles with rubber corks, as shown in Fig.1.4.

Figure 1.4:

*   Remove the pistons from all the syringes.

*   Leaving one syringe untouched, fill water in the second and pieces of chalk in the third.

*   Insert the pistons back into the syringes. You may apply some vaseline on the pistons before inserting them into the syringes for their smooth movement.

*   Now, try to compress the content by pushing the piston in each syringe.

*   What do you observe? In which case was the piston easily pushed in?

*   What do you infer from your observations?

We have observed that gases are highly compressible as compared to solids and liquids. The liquefied petroleum gas (LPG) cylinder that we get in our home for cooking or the oxygen supplied to hospitals in cylinders is compressed gas. Compressed natural gas (CNG) is used as fuel these days in vehicles. Due to its high compressibility, large volumes of gas can be compressed into a small cylinder and transported easily.

We come to know of what is being cooked in the kitchen without even entering there, by the smell that reaches our nostrils. How does this smell reach us? The particles of the aroma of food mix with the particles of air spread from the kitchen, reach us, and even farther away. The smell of hot cooked food reaches us in seconds; compare this with the rate of diffusion of solids and liquids. Due to the high speed of particles and large space between them, gases show the property of diffusing very fast into other gases.

In the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.

Figure 1.5: a, b and c show the magnified schematic pictures of the three states of matter. The motion of the particles can be seen and compared in the three states of matter.

Source: This topic is taken from NCERT TEXTBOOK

PLASMA

PLASMA

The state consists of super energetic and super excited particles. These particles are in the form of ionised gases. The fluorescent tube and neon sign bulbs consist of plasma. Inside a neon sign bulb there is neon gas and inside a fluorescent tube there is helium gas or some other gas. The gas gets ionised, that is, gets charged when electrical energy flows through it. This charging up creates a plasma glowing inside the tube or bulb. The plasma glows with a special colour depending on the nature of gas. The Sun and the stars glow because of the presence of plasma in them. The plasma is created in stars because of very high temperature.

Source: This topic is taken from NCERT TEXTBOOK

BOSE-EINSTEIN CONDENSATE

BOSE-EINSTEIN CONDENSATE

In 1920, Indian physicist Satyendra Nath Bose had done some calculations for the fifth state of matter. Building on his calculations, Albert Einstein predicted a new state of matter – the Bose-Einstein Condensate (BEC). In 2001, Eric A. Cornell, Wolfgang Ketterle, and Carl E. Wieman of the USA received the Nobel prize in physics for achieving “ Bose-Einstein condensation ”. The BEC is formed by cooling a gas of extremely low density, about one-hundred-thousandth the density of normal air, to super-low temperatures.

Source: This topic is taken from NCERT TEXTBOOK