Ch 10Surface Chemistry — Class 12 Chemistry, concept-first.

Why can mosquitoes and other small insects walk on water, yet sink the moment soap is added nearby? Why do water droplets and mercury droplets pull themselves into near-perfect spheres? Why are a butt…

A solid's surface behaves quite differently from its bulk interior. Atoms deep inside a crystal or a lump of metal have all their bonding capacity satisfied by neighbouring atoms on every side, but at…

Depending on the nature of the forces holding the adsorbate to the adsorbent, adsorption is classified into two distinct kinds: physical adsorption (physisorption) and chemical adsorption (chemisorpti…

The extent to which a gas is adsorbed onto a solid surface — how much adsorbate accumulates per unit mass of adsorbent — depends, qualitatively, on four factors: the nature of the adsorbent, the natur…

The amount of gas held on a solid adsorbent is jointly a function of both temperature and pressure (or concentration, for adsorption from solution), so this relationship can be examined in two complem…

Adsorption isotherms can also be examined quantitatively: a plot of the amount of adsorbate adsorbed against the pressure (or, for adsorption from solution, the concentration of the adsorbate) at cons…

Adsorption underlies an enormous range of practical applications, of which thirteen representative examples are collected here.

In 1836, the Swedish chemist Berzelius noticed that certain substances, when present during a chemical reaction, loosened the bonds within the reacting molecules and thereby increased the rate of the…

A catalyst obeys a well-defined set of characteristics, regardless of the specific reaction it is accelerating (or retarding).

For any chemical reaction to occur, the reactant molecules must first be activated into an 'activated complex', and the minimum energy required to bring the reactants to this activated state is the ac…

Enzymes are complex protein molecules built around elaborate, precisely-folded three-dimensional structures, and it is this structure — not their chemical formula alone — that lets them catalyse the s…

The generally accepted mechanism for enzyme catalysis proceeds through a short-lived enzyme–substrate complex:

No account of heterogeneous catalysis would be complete without zeolites — microporous, crystalline, hydrated aluminosilicate minerals built from a three-dimensional network of silicon and aluminium t…

The systematic study of colloids traces back to Thomas Graham, who observed that solutions of sugar, urea or sodium chloride diffused readily through a parchment membrane, while glue, gelatine and gum…

Colloidal systems can be classified along several independent lines, each capturing a different physical feature of the system.

Some lyophilic substances form colloidal solutions almost spontaneously — warming certain substances gently in water is enough, rubber dissolves directly into benzene to give a colloidal solution, and…

Whatever method is used to prepare a colloidal solution, the resulting sol commonly carries dissolved electrolyte and other soluble impurities left over from the preparation process, and if these impu…

Colloidal solutions show a distinctive combination of physical, optical, kinetic and electrical properties that set them apart both from true (molecular) solutions and from ordinary coarse suspensions…

An emulsion is a colloidal solution in which one liquid is finely dispersed, as tiny droplets, throughout another liquid with which it is immiscible.

Deemulsification is the process of splitting a stable emulsion back down into its two original, separate liquid layers — essentially reversing emulsification.

Colloids and surface chemistry touch nearly every corner of daily life. The human body itself is built substantially around colloidal systems — blood, the protoplasm of plant and animal cells, and the…

Sample papers and previous-year board questions for this subject.