INTRODUCTION/ DEFINITIONS:
The inter particle forces of attraction are not very strong in water.
The inter particle spaces are somewhat large in water.
Particle size is extremely small and are in a state of motion
Inter particle attractions keep particles close
The density of a substance depends upon the number of particles per unit volume as well as upon their mass. The number of the particles is related to their size as well as the attractive forces among them.
The molecules in a gas have large kinetic energy.
In air, the interparticle spaces are very large in number and the interparticle forces are quite weak. These can be easily overcome.
Boiling point temperature of water is 100°C. Above this temperature (250°C), water exists in the gaseous state i.e., as vapours or as steam.
In a liquid, the particles or molecules experience mutual forces of attraction. However, these are not stationary and have some kinetic energy at all temperatures. The particles of a liquid are also colliding with one another and exchanging energy during the collisions.
At 25°C, water is in the liquid state (b) At 0°C, water can exist both in the solid state (ice) and in liquid state. This temperature represents the melting point of ice and freezing point of water (c) At 100°C, water can be present both in the liquid and vapour states
Fluidity means tendency to flow. The constituents in the solids are very closely packed and interparticle forces are quite strong.
Freezing point temperature of water : 0°C or 273 K and boiling point temperature of water : 100°C or 373 K.
In gases, the inter particle or inter molecular spaces are very large. These can be decreased to a large extent on applying pressure.
When boiling water changes into steam, it absorbs a certain amount of heat energy. This shows that the latent heat of vaporisation of steam is more than that of boiling water.
The diffusion of a gas is not affected by gravity
Substances undergo change in physical state because both interparticle spaces and interparticle forces can be changed by changing the conditions of temperature and pressure.
Steam is formed when water at its boiling point temperature of 100°C (373 K) absorbs latent heat of vaporisation
The amount of heat energy which is needed to convert one kg of a solid into the liquid state at its melting point temperature without any rise in temperature under one atmosphere pressure is latent heat of fusion.
Melting point is the temperature at which a solid starts melting or starts changing into the liquid state.
Fusion is the process of the change of the solid state into the liquid state.
The intermolecular force of attraction is maximum in the solid state and minimum in the gaseous state.
Similarly, the kinetic energy of the molecules is minimum in the solid state and maximum in the gaseous state.