If you are a Grade IX level student, or preparing yourself for competitive/entrance exams and looking for study notes on the topic of "The physical States of Matter" such as basic terms/definitions used in Physical states of matter, intermolecular forces in three states of matter, typical properties of Gases, Liquids, and Solids
Define the following
i. Matter
ii. Solid
iii. Liquid
iv. Gas
1. Matter
Anything which occupies space and has mass is called matter.
For example, any solid, liquid, and gas are examples of matter because all these states of matter have mass and they also occupy space.
2. Solid
The state of matter that has a fixed shape and volume is called solid.
For example, chair is a solid as it has fix shape and fix volume, it is because the intermolecular forces of attraction in solids are stronger than in liquids and gases. Solids are usually hard.
3. Liquid
The state of matter with a fixed volume but unfix shape is called liquid.
For example, water is liquid because it has a fixed volume but doesn’t have fix shape and so assume the shape of a container. Liquids can usually flow.
4. Gas
The state of matter which has an indefinite shape and indefinite volume is called gas.
What do you mean by Inter-molecular attractive forces? Explain your answer for three states of matter.
Intermolecular attractive forces
The forces of attraction present between the molecules of a substance are called Inter-molecular attractive forces.
Explanation
Intermolecular attractive forces are much weaker than chemical bonds. The physical properties such as melting point, boiling point, density, vapor pressure, etc depend on the strength of Inter-molecular attractive forces. Intermolecular attractive forces are much weaker in gases than in solids and liquids.
1. Inter-molecular attractive forces in Solids
Solids are hard because Inter-molecular attractive forces in solid molecules are strong enough to keep them tight due to this, there is little space between them, and they become hard.
2. Inter-molecular attractive forces in Liquids
Liquids can flow because Inter-molecular attractive forces in liquid molecules are not too much stronger enough to keep those tight due to which there will be more space between liquid molecules and then they can flow.
3. Inter-molecular attractive forces in Gases
Gases are not hard because Inter-molecular attractive forces in gas molecules are very much weak than solids and liquids due to which there is more space between gas molecules and they become invisible.
What are some of the typical properties of Gases?
Typical properties of Gases
Following are some of the typical properties of Gases
1. Indefinite volume
Gases can move freely in all directions therefore they can occupy all the space available, so they have indefinite volume.
2. Indefinite shape
Gases have no regular shapes but they occupy the shape of the container in which it is contained because they can move freely.
3. Pressure
As gas molecules can move freely so they collide with each
other and also with the walls of the container, by doing so they exert pressure.
This pressure increases with an increase in temperature. Normal atmospheric pressure is 760mm of Hg or 1 atmosphere.
4. Compressibility and Expansion
By applying pressure on gases they can be compressed i.e their molecules get nearer. Similarly, by decreasing pressure they expand i.e their molecules go further away.
5. Mobility
The distance between gas molecules is very large so they can move freely i.e. they are mobile.
6. Diffusion
Diffusion means the mixing of gases, by definition
The spontaneous mixing of the molecules of one gas with another at a given temperature and pressure is called Diffusion.
The greater the mass of the gas lesser will be the diffusion.
7. Effusion
The escaping of the gas molecules one by one from the container through a small hole of molecular size is called Effusion.
So gases can be escaped one by one.
8. Density
Mass per volume is called Density.
The density of the gases is very low compared to the same amount of solids or liquids, so the density of a gas is inversely proportional to its volume.
Differentiate between Diffusion and Effusion.
Difference between Diffusion and Effusion
|
Sr# |
Basis
of distinction |
Diffusion |
Effusion |
|
1 |
Definition |
The movement of gaseous molecules from the region of higher concentration to the region of lower concentration is called diffusion. |
The movement of gaseous molecules from the region of higher concentration to the region of lower concentration through a small hole of molecular size is called effusion. |
|
2 |
Nature of process |
Diffusion is a non-controllable process. |
Effusion is a controllable process. |
|
3 |
Condition |
There is no need for a small hole of molecular size for diffusion. |
There must be a tiny hole of molecular size for effusion. |
|
4 |
States of Matter |
Diffusion can take place in solids, liquids, and gases. |
Effusion takes place only in gas molecules. |
|
5 |
Examples |
The spreading of rose smell in the area nearby the garden. |
Puncturing of the tire, escaping out of gas out of balloon without bursting. |
What are the typical properties of Solids?
Typical properties of the Solids
Some of the typical properties of the Solids are given as
1. Definite Volume and Shape
Solids have strong inter-molecular forces due to which their molecules are tightly packed and so solids have definite volumes and definite shapes.
2. Rigidity
Solids oppose the forces that change their shape (called deforming force) because of strong intermolecular forces. So solids are rigid (hard).
4. Density
Mass per volume is called Density. Solids have their molecules very close to each other, so their mass per unit volume is much greater than Liquids and Gases. So Solids are denser.
5. Melting point
The temperature at which Solids change into Liquids is called their Melting point.
The melting point neither changes nor remains constant until the whole Solid changes into Liquid. The purity of crystalline solids can be checked by melting point because the melting point is one of the characteristic properties of crystalline solids.
What are the main types of Solids? Give some examples
Types of Solids
Solids are arranged according to the regular and irregular patterns of their molecules. Following are the two main types of Solids.
1. Crystalline Solids
Those types of solids in which their particles (ions, atoms, or molecules) are arranged in a regular pattern to form three-dimensional shapes are called Crystalline Solids.
Explanation
As molecules of Solids are closely packed to each other, if they are arranged in a regular pattern, they will be Crystalline Solids. Pure crystalline Solids have sharp melting points.
Examples
Sodium Chloride and Naphthalene are Crystalline Solids.
2. Amorphous Solids
The type of solids in which their particles (ions, atoms, or molecules) are not arranged in a regular pattern to form three-dimensional shapes are called Amorphous Solids.
Explanation
As molecules of Solids are closely packed to each other so if they are not arranged in a regular pattern then they will be amorphous Solids. They are pure Solids but instead of having sharp melting points, they vary.Examples
Glass, Waxes, and Plastics are Amorphous Solids.
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