# NEET Chemistry Surface Chemistry Questions Solved

BOARD

Explain clearly how the phenomenon of adsorption finds application in

(i) production of vacuum in a vessel

(ii) heterogeneous catalysis

(iii) froth floatation process in metallurgy.

(i) Production of vacuum: In Dewar flasks, activated charcoal is placed between the

walls of the flask so that any gas which enters into annular space either due to

glass imperfection or diffusion through glass is adsorbed and create a vacuum.

(ii) Heterogeneous catalysis: If the catalyst is present in a different phase than

that of the reactants, it is called a heterogeneous catalyst and this type of

catalysis is called Heterogeneous catalysis.

Example: Manufacture of from ${\mathrm{N2}}_{}$ and ${\mathrm{H2}}_{}$ by Haber's process using iron

as catalyst

N2 (g) + 3H2 (g) $\stackrel{Fe\left(s\right)}{\to }$ 2NH3 (g)

Reactants are gaseous whereas catalyst is solid.

(iii) Froth Floatation process: when KCl is added to hydrated ferric oxide sol, then

a negatively charged sol is obtained with absorption of  ion.

Difficulty Level:

• 50%
• 20%