Colloids

Question 1

Colloid is derived from the Greek word _____ - _____, and _____ - _____

Answer 1

Kola- glue
Eidos- like

Question 2

Is a dispersion of particles of one substance throughout a dispersing medium mass of another substance

Answer 2

Colloid

Question 3

EXAMPLES OF COLLOIDS

Answer 3

Starch in water
Gelatin

Question 4

TWO COMPONENTS OF COLLOIDS

Answer 4

Dispersed phase
Dispersion medium

Question 5

Colloidal particles range from _____ - _____

Answer 5

1x10^3 to 1x10^6 pm

Question 6

TWO TYPES OF MIXTURES

Answer 6

Homogenous mixture / Solution
Heterogenous mixture / Suspension

Question 7

• Tiny partticles such as atoms, ions, small molecules
• Uniform appearance
• Does not settle out

Answer 7

Homogenous Mixture (solution)

Question 8

• Parts do not dissolve
• You can see distinct parts
• The parts may suspend, but they always settle down

Answer 8

Heterogenous mixture (suspension)

Question 9

• Intermediate particles
• Visible
• Stays suspended

Answer 9

Colloids

Question 10

Dispersed systems consists of particulate matter

Answer 10

Dispersed phase

Question 11

Distributed throughout a continuous phase

Answer 11

Dispersion medium

Question 12

• Particles are invisible in electron microscope
• Pass through semipermeable membranes and filter paper
• Particles do not settle down in standing
• Under rapid diffusion

Answer 12

Molecular dispersions

Question 13

TYPES OF COLLOIDS

Answer 13

Molecular dispersions
Colloidal dispersions
Coarse dispersions

Question 14

• Particles not resolved by ordinary microscope, can be detected by electron microscope
• Pass through filter paper but not pass through semipermeable membrane
• Particles made to settle by centrifugation
• Diffuse very slowly
  Ex: colloidal silver sols, natural and synthetic polymers

Answer 14

Colloidal dispersions

Question 15

• Particles are visible under ordinary microscope
• Do not pass through filter paper or semipermeable membrane
• Particles settle down under gravity
• Do not diffuse
  Ex: emulsions, suspensions, red blood cells

Answer 15

Coarse dispersions

Question 16

Dispersing medium and Dispersed phase of AEROSOL (fog)

Answer 16

DM: gas
DP: liquid

Question 17

Dispersing medium and Dispersed phase of AEROSOL (smoke)

Answer 17

DM: gas
DP: solid

Question 18

Dispersing medium and Dispersed phase of FOAM (whipped cream)

Answer 18

DM: liquid
DP: gas

Question 19

Dispersing medium and Dispersed phase of EMULSION (mayonnaise)

Answer 19

DM: liquid
DP: liquid

Question 20

Dispersing medium and Dispersed phase of SOL

Answer 20

DM: liquid
DP: solid

Question 21

Dispersing medium and Dispersed phase of FOAM (plastic foam)

Answer 21

DM: solid
DP: gas

Question 22

Dispersing medium and Dispersed phase of GEL

Answer 22

DM: solid
DP: liquid

Question 23

Dispersing medium and Dispersed phase of SOLID SOL

Answer 23

DM: solid
DP: solid

Question 24

A mixture of two or more liquids that are usually immiscible

Answer 24

Emulsion

Question 25

In the presence of _____, the two immiscible liquids are agitated together

Answer 25

Emulsifier

Question 26

EXAMPLES OF EMULSION

Answer 26

Mayonnaise, milk, butter

Question 27

Used in butter and milk that acts as an emulsifying agent

Answer 27

Casein

Question 28

Solvent attracting / solvent loving

Answer 28

Lyophilic colloids

Question 29

They have great affinity for the solvent and do not precipitate easily

Answer 29

Lyophilic colloids

Question 30

If the dispersion medium is separated from the dispersed phase, the sol can be reconstituted by simply remixing with the dispersion medium. These sols are called _____

Answer 30

Reversible sols

Question 31

Solvent repelling / solvent hating

Answer 31

Lyophobic colloids

Question 32

These colloids are easily precipitated on the addition of small amounts of electrolytes by heating or shaking - less vicid

Answer 32

Lyophobic colloids

Question 33

Once precipitated, it is not easy to reconstitute the sol by simply mixing with the dispersion medium. These are called _____

Answer 33

Irreversible sols

Question 34

Type of colloid which act as a normal strong electrolytes at low concentration, but exhibit colloidal particles at higher concentration due to the formation of aggregated particles

Answer 34

Association / Amphiphilic Colloids

Question 35

The concentration at which micelle form

Answer 35

Critical micelle concentration

Question 36

50 or more amphiphiles

Answer 36

Micelles

Question 37

CHARACTERISTICS OF COLLOIDS

Answer 37

- reflect or scatter light (tyndall effect) - filtration - thermodynamically unstable but kinetically stable - classified according to dispersed substance in dispersed medium

Question 38

Scattering of light

Answer 38

Tyndall effect