Three states of matter
Introduction to States of matter:
We know that, there are three states of matter or matter exists in three states, which are Solid, Liquid and gaseous. In solid state, the matter have definite volume, shape, and mass. The atoms in the solid state are packed closely closely by strong intermolecular attractive forces.
Some common examples of solids are Gold, Steel, Comman salt, Sugar, ice etc.
Second state of matter is Liquid state, which have definite mass and volume, but not the definite shape. Liquid acquires the shape of the container in which it is filled. And the atoms or molecules in liquid state are loosely packed due to comparatively weaker intermolecular attractive forces than solids.
Examples of liquids are water milk, oil, kerosene etc.
Third state of matter is gaseous state which does not have definite shape or volume, but it has definite mass. A gas occupies whole volume of the container in which it is filled and takes the shape of the container. In gases intermolecular attractive forces are negligible. Therefore the movement of gas is very rapid and random. The speed of gas can only be understood by havoc caused by storms.
Examples of gaseous are Air, Oxygen, Neon, Vapour etc.
Classification of Solids:
We know that, in solids the intermolecular forces of attraction are very strong. These intermolecular forces of attraction reduce the intermolecular distance considerably. Solids are incomprehensible and rigid.
Solids are classified into two types:
1) Amorphous solids:
a) In Amorphous solids constituents are not arranged in an orderly manner.
b) The structure of amorphous solids is similar to that of liquids.
c) Glass, rubber, and plastic are the examples of the amorphous solids.
d) Amorphous solids soften over a range of temperature and can be moulded and blown in various shape.
2) Crystalline solids:
a) Crystalline solids consists of large number of small crystals having definite characteristics geometrical shape.
b) Iron, zinc, copper, silver and gold etc. metallic elements and nonmetals like sulphur,phosphorus,iodine, and compounds like sodium chloride,zinc sulphate,naphthalene etc. are the examples of the Crystalline solids.
Based on the nature of intermolecular forces of attraction crystalline solids are classified in four classes:
1) Ionic solids:
Ionic solids are three dimensional arrangements of anions and cations held together by strong electrostatic force of attraction. Ionic solids are hard and brittle. They have high melting and boiling points.
Ionic solids Due to equal number of positive and negative charges in solid, the crystal as a whole is electrically neutral. Ionic solids are generally soluble in water.
Examples: NaCl, CuSO4, MgO, AlCl3 etc. These ions in the solids are not free to move but when dissolved in water move freely.
2) Covalent solids:
The solids in which the constituent particles are held together by covalent bond are called as covalent solids. They are aslo known as network solids. Covalent solids have high melting points and boiling points. These solids do not conduct electricity and form giant molecules. These are hard solids.
Covalent solids
Examples: Diamond, silica, boron, etc.
Exceptionally graphite is soft through it is covalent solid.
3) Metallic Solids:
These are the solids consisting of positively charged metal ions which are embedded together in the sea of delocalized electrons. These solids are conductors of heat and electricity. These soilds possess luster and colour. These solids are malleable and ductile. Some of them are soft while some are hard.
Metallic solids
Examples: Sodium, Potassium, Aluminum, zinc, etc.
4) Molecular solids:
In molecular solids, the molecules are held together by weak van der waals force of attention.
These solids are soft, easily compressible. They have low melting point. They do not conduct heat and electricity.
Molecular solids
Examples: Ice, urea, naphthalene, sugar, glucose, camphor, solid CO2, solid SO2, solid NH3, solid Ar and solid He etc.
Liquid state:
Properties of liquids:
1. In liquid state inter-molecular attractive forces are stronger than gases but weaker than solids.
2. The molecules do not occupy all the space available but takes the shape of the container, thus do not have a definite shape.
3. The density of a liquid is much higher than any gas.
4. Due to smaller size of their intermolecular voids, liquids are almost incomprehensible. This property of liquids is used in hydraulic brakes in automobiles.
5. The molecules of liquids are in constant random motion. Thus the molecules of a liquid undergo diffusion but at slower rates as compound to gases.
6. Liquids undergo boiling at specific temperature. This is known as boiling point of the liquid at which the vapour pressure of liquid and the atmospheric pressure are equal.
7. Different liquids flow with different rates due to differences in their molecular friction which is also known as viscosity.
Gaseous state:
Properties of gases:
1. In gaseous state intermolecular attraction is very weak.
2. The molecules of gases occupy all the space available to them.
3. The density of the gases is lower than liquids and solids.
4. The molecules of gases are always in constant random motion hence they possess kinetic energy. Gases undergo diffusion with faster rate than liquids. Different gases diffuse in to each other to form homogenous mixture.
5. Gases have high expansion power and high compressibility. This property of gases is used in several pneumatic instruments, like automobile brakes and in JCB.
6. Gases exert pressure on the walls of the container in all the directions in which they move.
7. In automobiles, the expansion of gas caused by burning the fuel is used in movement of pistons which in turn move the vehicles.
Gas Law:
The interaction of gaseous molecules can be learnt by interdependence of their physical properties. These facts can be expressed in the form of gas laws.
Boyle's Law:
In 1662, Robbert Boyle, an Anglo-Irish scientist studied variation of pressure of a givan mass of gas with volume at constant temperature.
Statement:
The pressure of the given mass of a gas varies inversely as its volume at a constant temperature.
Mathematically, for a given mass of a gas constant temperature, the law may expressed as:
P= K\V
Where K is proportionally constant
i.e. PV=K= constant
Hence for a given mass of a gas, the product of pressure and volume is constant temperature.
Charle's law:
Statement:
The law states that, As the temperature of sample increases, the volume increases at constant pressure.
V1/T1 =V2/T2 = Constant.
Difference between ideal gas and real gas:
Difference between ideal gas and real gas So, this are the information about three states of matter.
