Chemistry (Part-XV)

The equation PV=NK_BT (or K_B​=PV/TN) represents the ideal gas law where:

• $P$ = pressure
• $V$ = volume
• $N$ = number of particles (atoms or molecules)
• $T$ = temperature (in Kelvin)
• K_B​ = Boltzmann constant

The Boltzmann constant (K_B​) is a fundamental physical constant that relates the average kinetic energy of particles in a gas with the temperature of the gas. The Boltzmann constant,
K_B has a defined value of 1.380649 × 10⁻²³ joules per kelvin (J/K) in the International System of Units (SI).

Homogeneous Mixture: A mixture where the components are uniformly distributed throughout the mixture, and individual components are not visible (e.g., salt dissolved in water, air).

Heterogeneous Mixture: A mixture where the components are not uniformly distributed, and individual components can often be seen or distinguished (e.g., sand and water, oil and water).

Compound: A substance formed when two or more chemical elements are chemically bonded together (e.g., water (H₂​O), salt ($NaCl$)).

Molecule: Two or more atoms held together by chemical bonds (e.g., O₂​, $CO₂$).

Soil is composed of various components like sand, silt, clay, organic matter (humus), water, and air, all mixed together but not chemically bonded. These components are not uniformly distributed; you can often see different particles or layers within a soil sample. Therefore, soil is a heterogeneous mixture.

In solids, particles (atoms, ions, or molecules) are:

1. Tightly packed: They are very close together in a fixed, regular arrangement (crystalline solids) or a disordered arrangement (amorphous solids).
2. Strong intermolecular forces: The forces holding them together are very strong.
3. Restricted movement: Particles in a solid are not free to move or flow past one another. Instead, they primarily vibrate about their fixed positions. They do not translate (move from one place to another) or rotate freely.

Therefore, molecules in solids "cannot move" in the sense of translating freely. They are fixed in position, only able to vibrate.

The traditional four states of matter are solid, liquid, gas, and plasma. However, at extreme conditions, other states can be observed:

Bose-Einstein Condensate (BEC): This state of matter is formed when a gas of bosons (particles with integer spin) is cooled to temperatures very close to absolute zero (typically nanokelvins). At these extremely low temperatures, the particles lose their individual identities and condense into the lowest possible quantum state, behaving as a single quantum entity. This phenomenon was first predicted by Satyendra Nath Bose and Albert Einstein.