Surface chemistry | diginotes

-Surface phenomenon

Absorption

-Bulk phenomenon

Adsorption: Accumulation of molecular species at the surface.

Adsorbate: the surface which gets absorbed on the surface

Adsorbent: The substance on which adsorption occurs

- Example : (1)SiO2 get keeps dry

(2)Aq soln of raw sugar becomes colourless when comes in contact with animal charcoal.

(3)organic dyes like methylene blue becomes colourless in animal charcoal.

only Cacl2

Mechanism of adsorption

1.Temperature: On increasing tempr. adsorption may increase or decrease. In general adsorption increases on increasing temperature.

Acc. to Le - chatelliers principle 

solid + gas ⇌ solid/gas + heat

2.Pressure : On increasing P, adsorption increases.

3.Surface Area : Surface area increases, adsorption easily adsorbed.(gases with high critical temperature get adsorbed easily.)

x/m = KP^1/n

m = mass of adsorbent 1/n lies b/w 0 to 1 (0.1 to 0.5)