Surface Chemistry

Question 1

Physical adsorption (physisorption) is weaker than chemical adsorption (chemisorpyion), but can occur simultaneously.

Answer 1

Example. Hydrogenation of alkenes using metal catalysts

Question 2

Condition of spontaneous adsorption

Answer 2

Exothermic enough to overcome the effect of negative change in Energy

Question 3

Models of adsorption at constant temperature

Answer 3

Adsorption isotherms

Question 4

Adsorption isotherms that assumes that ideal gas is absorbed as monolayer ona solid surface

Answer 4

Langmuir

Question 5

Adsorption isotherms thats only limited up to the saturation point. Mostly applicable to physisorption

Answer 5

Freundlich

Question 6

Mixtures that have dispersed particles larger than solutes but smaller for mixture to become heterogeneous

Answer 6

Colloids

Question 7

Colloidal mixture can be detected using ___

Answer 7

Tyndall effect

Question 8

Formation of colloids

Breaks down
Come together

Answer 8

Dispersion
Condensation

Question 9

Can be formed easily as long as the solid (dust) or liquid (spray) particles are of colloidal size

Answer 9

Aerosols

Question 10

Can be formed by introducing a gas in solid structure

Answer 10

Foams

Question 11

Can be formed by dispersion of liquids that are initially heterogeneous

Answer 11

Emulsions

Question 12

___ are added to stabilize emulsions by retaining colloidal size of the dispersed liquid

Answer 12

Emulsifiers

Question 13

Starts with liquid solution, then eventually solidifies. Ex. Gelatin cheese

Answer 13

Gels

Question 14

Solid sols prepared like gels
Liquid sols, the medium retain it’s liquid form

Answer 14

Sols can be lipophilic (high affinity for solvents) or lyophobic sols

Question 15

___ sols are unstable, solid particles may coagulate through time

Answer 15

Lyophobic

Question 16

___ are added to deter coagulation by forming a protective layer around the lyophobic sols.

Answer 16

Lyophilic sols

Question 17

Protective power of lyophilic sol is quantified using ___

Answer 17

Gold number. Greater gold number means weak protective power.

Question 18

If quick coagulation is desired ___ is added forming precipitates

Answer 18

Electrolyte