Acetyl chloride on reduction with H2 in presence of Pd as catalyst gives ethanol, whereas in presence of Pd-BaSO4, it gives ethanal.

Solutions are homogenous systems e.g. sugar solution. If sand is stirred in water, it slowly settles down and is called a suspension. Between the extremes of suspensions and solutions a large group of systems called colloidal dispersion or simply colloids exist.

A colloidal is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium. The essential difference between a solution and a colloidal is one of particle size. In a solution, the particles or ions are small molecules. In a colloid, the dispersed phase may consist a particles of a simple macromolecule (such as protein or synthetic polymer) or an aggregate of many atoms, ions or molecules. Colloidal particles are larger than simple molecules but small enough to remain suspended. They have a range of a diameter between 1 and 1000 nm.

Comment on the statement that “colloid is not a substance but a state of substance”.

Any substance (solid, liquid or gas) using special method can be brought into colloidal state. For example, NaCl in water forms true solution but in benzene forms colloidal solutions in alcohol but colloidal in water.

If H+ (ion) is accelerated to a final velocity of 6.62×10+6 meter per second and error in velocity is 1% then find uncertainty in position is?

What is the relation between Total energy (TE), Kinetic energy (KE) and Potential energy (PE) of Bohr's orbits?

Relation between Total energy (TE), Kinetic energy (KE) and Potential energy (PE):

Important conclusions:

(1) The minus sign for the energy of an electron in an orbit represents attraction between the +vely charged nucleus and negatively charged electron.

(2) Energy of an electron at infinite distance from the nucleus is zero.

(3) As an electron approaches the nucleus, the electrical attraction increases, energy of electron decreases and it becomes negative.

(4) Energy of an electron increases as the value of ‘n’increases i.e.

(5) Value of ‘n’ remaining unchanged, the amount of energy associated with an electron remains unaltered.

(6) Energy of electron in first, second, third and fourthorbit are –13.6, –3.4, –1.5, and –0.85 eV/atomrespectively.

(7) Although the energy of electron increases with increase in the value of ‘n’ (orbit), yet the difference of energy between successive orbits decreases. Thus E₂ – E₁ > E₃ – E₂ > E₄ – E₃ > E₅ – E₄ >, etc…

How to calculate energy of Bohr's orbits in term of Rydberg's constant

Energy in term of Rydberg’s Constant: