LEC 17: Colloids

Question 1

dispersion in which the dispersed particles are larger than the solute ion or molecules of a true solution and smaller than the particles of a mechanical suspension

Answer 1

colloids

Question 2

dispersion in which microscopically visible particles are mixed with, but not dissolved n a fluid or solid

Answer 2

suspension

Question 3

colloid is derived from the Greek word ___ meaning ____

Answer 3

• kolla
• glue

Question 4

the term colloid does not imply a system has a ____ quality

Answer 4

gluelike

Question 5

fundamental difference between a colloidal dispersion and a true solution

Answer 5

size of the particles

Question 6

size of solute particles in ordinary solutions

Answer 6

0.1 to 1nm

Question 7

size of colloidal particles

Answer 7

1 to 1000 nm

Question 8

in a solution, the particles are usually single ___ or ____

Answer 8

• ions
• molecules

Question 9

in a colloid, the particles are usually _____ of ions or molecules

Answer 9

aggregation

Question 10

types of colloidal dispersion

Answer 10

• foam
• solid foam
• emulsion
• solid emulsion
• solid aerosol
• sol
• solid sol

Question 11

type of colloidal dispersion in foam

Answer 11

gas in liquid

Question 12

type of colloidal dispersion in liquid aerosol

Answer 12

liquid in gas

Question 13

type of colloidal dispersion in solid foam

Answer 13

gas in solid

Question 14

type of colloidal dispersion in emulsion

Answer 14

liquid in liquid

Question 15

type of colloidal dispersion in solid emulsion

Answer 15

liquid in solid

Question 16

type of colloidal dispersion in solid aerosol

Answer 16

solid in gas

Question 17

type of colloidal dispersion in sol

Answer 17

solid in liquid

Question 18

type of colloidal dispersion in sol

Answer 18

solid in solid

Question 19

who illuminated an aqueous suspension of pollen under a high powered microscope in 1827

Answer 19

Robert Brown

Question 20

brown observed a trembling _____ of the pollen grains

Answer 20

erratic motion

Question 21

the erratic motion of pollen grains is a characteristic of ____

Answer 21

colloids

Question 22

the random motion of pollen grains is called ______

Answer 22

brownian movement

Question 23

_____ occurs because colloidal particles are large enough to scatter light

Answer 23

tyndall effect

Question 24

colloidal particles have ____ surface areas in comparison to the volume of the same particles if they were aggregated into one large particle

Answer 24

huge

Question 25

colloidal particles become _____ when they adsorb ions on their surfaces

Answer 25

electrically charged

Question 26

what occurs when the surface atoms of the colloid attract or adsorb ions or polar molecules from the dispersion medium

Answer 26

electrically charged colloid particles

Question 27

mixture that completely combines to form a solution

Answer 27

miscible

Question 28

miscible liquids or mixture do not produce a ____ to create a completely new solution

Answer 28

meniscus

Question 29

two materials are said to be miscible if they ____ to form a homogenous mixture

Answer 29

combine

Question 30

inability to combine two different liquids

Answer 30

immiscible

Question 31

vital when we want to successfully emulsify or combine immiscible liquids

Answer 31

emulsifiers or emulsifying agents

Question 32

emulsifiers are substances that help _____ an emulsion to allow it o stay in this form for a significant amount of time

Answer 32

stabilize

Question 33

example of emulsifying agents

Answer 33

- egg yolks - lecithin - mustard - sodium phosphate - detergent - emulsifying wax

Question 34

an emulsion is a____ of any two liquids that do not stay mixed and do not form a permanent mixture

Answer 34

suspension

Question 35

oil is _____ while vinegar is _____

Answer 35

- non-polar - polar

Question 36

vinegar is ____ than the oil

Answer 36

denser