Coarse dispersion systems ✅

Question 1

What is a dispersion system?

Answer 1

A system consisting of two or more phases.
1) the dispersed phase
2) the dispersed medium, continuous phase

Question 2

What type of dispersion do heterogenous mixtures undergo?

Answer 2

coarse dispersion and colloidal dispersion

size > 100nm / size 1-100nm

Question 3

What type of disperse systems do homogenous mixtures undergo?

Answer 3

molecular dispersion

size < 1nm

Question 4

What are some features of molecular dispersion?

Answer 4

• cannot be filtered through filter paper
• cannot be seen with a naked eye

Question 5

What are some features of coarse dispersion?

Answer 5

• easily filtered with filter paper (filtration)
• relatively fast sedimentation (caused by gravity or other forces)

Question 6

What is suspension? How is dispersion achieved?

Answer 6

heterogenous fluid containing solid particles that are sufficiently large for sedimentation.
- dispersion is made by mechanical agitation (eg. sand in water)

Question 7

What is emulsion?

Answer 7

suspention of liquid droplets (dispersed phase) of a certain size within a second immiscible liquid (continuous phase).

Question 8

What are the two types of emulsion classifications?

Answer 8

1) Oil in Water (O/W)
2) Water in Oil (W/O)

Question 9

What is an oil in water emulsification?

Answer 9

oil droplets dispersed in water (eg. milk)

Question 10

What is a water in oil emulsification?

Answer 10

water droplects dispersed in oil (butter)

Question 11

What is a colooidal dispersion?

Answer 11

a system in which particles of colloidal size (1-100nm) if any state are dispersed in a continuous phase of a different state.

Question 12

What are colloids?

Answer 12

• a homogeneous non-crystalline substance consisting of large molecules or ultramicroscopic particles of one substance dispersed through a second substance.
• colloids include gels, sols, and emulsions;
• the particles do not settle,
• particles cannot be separated out by ordinary filtering or centrifuging like those in a suspension.

a substance of gelatinous consistency.

Question 13

What is the difference between a colloid and a crystalloid?

Answer 13

colloid- substances that do not diffuse through a semipermeable membrane
crystalloid- substances which do diffuse and are in true solution

Question 14

What are the three classifications of colloids?

Answer 14

1) lyophilic colloids
2) lyophobic colloids
3) associated colloids

Question 15

What are lyophobic colloids?

Answer 15

solvent ‘hating’
- mixed with a suitable liquid, very weak force of attraction,
- difficult to prepare
- less stable
- IRREVERSIBLE IN NATURE

Question 16

What are lyophillic colloids?

Answer 16

solvent ‘loving’ colloids
- mixed with a suitable liquid, high force of attraction,
- stable solution
- do not precipitate
- eg. gums, starch and proteins

exception:
- addition of very high amounts of electrolytes may cause precipitation
- addition of excessive liquid: regain original state

REVERSIBLE IN NATURE

Question 17

What is coagulation?

Answer 17

the instability of a colloidal solution.

Question 18

How can coagulation occur?

Answer 18

• heating
• increasing concenration
• adding electrolytes
• adding another colloid (oppositely charged particles)

Question 19

How are lyophobic solutions prepared?

Answer 19

1) condensation method
2) dispersion method

Question 20

What are the different condensation methods?

Answer 20

chemical:
1) by oxidation (bubbling oxygen through solution)
2) by reduction
3) by hydrolysis

physical:
1) exchange of solvent
2) excessive cooling

Question 21

What are the different dispersion methods?

Answer 21

1) mechanical dispersion
2) peptisation (adding of electrolyte)

Question 22

What are the properties of colloids?

Answer 22

physical:
1) heterogenous nature
2) stable nature
3) filterability

mechanical:
1) brownian movement (always move)
2) diffusion
3) sedimentation

optical:
1) tyndall effect (scattering of light)

Question 23

What is a micelle?

Answer 23

• colloidal shized particle formed by the association of molecules having a hydrophobic tail and hydrophillic head.
• electrically neutral
• contains:
  a) nucleus
  b) 2 layers of ions (as the shell)
• absorb ions

Question 24

What is a colloid called in which the dispersed phase consists of micelles?

Answer 24

association colloid

Question 25

What is the layer of ions closer to the nucleus called in micelles?

Answer 25

the adsorption layer

Question 26

What is the layer of ions further from the nucleus called in micelles?

Answer 26

the diffusion layer

Question 27

{m[Fe(OH)3] * nFeO+ * (n-x)Cl- x+ * xCl-}

What is:
1) {m[Fe(OH)3] * nFeO+ * (n-x)Cl- x+ * xCl-}
2) m[Fe(OH)3]
3) nFeO+ * (n-x)Cl- x+
4) xCl-
5) {m[Fe(OH)3] * nFeO+ * (n-x)Cl- x+

Answer 27

1) micelle
2) nucleus
3) adsorption layer
4) diffusion layer
5) granule

Question 28

What is a true solution? What is a solute? What is a solvent?

Answer 28

homogenous mixture of 2+ substances
- cannot be seen with a naked eye
- cannot be filtered

solute: component that is dissolved
solvent: dissolving agent (most abundant component in solution

Question 29

What is typically the solvent?

Answer 29

1) the substance which determines the state of the finished solution
2) the solution which is present in th ehighest concentrations

Question 30

How are solutions classified according to electrical conductivity?

Answer 30

1) electrolytes (conducting substance)
2) non-electrolytes (non-conducting substance)

Question 31

What are miscible liquids? What are immiscible liquids?

Answer 31

Miscible- completely soluble (solute and sovent are both polar or non polar)
Immiscible- insoluble (one of solute and sovent is polar and teh other is non polar)

Question 32

What affects solubility?

Answer 32

1) nature of the solvent (electronegativity, polarity, asymetry)
2) temperature (increase = increase)
3) pressure (increase = increase)

Question 33

What is a saturated solution?

Answer 33

solution containing the maximum quantity of solute that dissolves at a certain temperature.

rate of dissolving = rate of crystalization

Question 34

What is an usaturated solution?

Answer 34

solution containing less than the maximum quantity of solute that dissolves at a certain temperature.

Question 35

What is an supersaturated solution?

Answer 35

solution containing more than the maximum quantity of solute that dissolves at a certain temperature.
- very unstable
- warming solvent will dissolve more

Question 36

What factors affect the rate of solubility?

Answer 36

• particle size (smaller = faster)
• temperature (higher = faster)
• concentration of solution (higher concentratin = slower rate)
• agitation/stirring (more = faster)

Question 37

What is a concentration of a solution? dilute? concentrated?

Answer 37

amount of solute dissolved in a giver quantity of solvent/solution.

dilute- small amount of solute
concentrated- large amount of solute

Question 38

How to calculate the mass percent solution?

Answer 38

mass of component / total mass of solution * 100%

Question 39

What is molarity?

Answer 39

the number of moles of solute per liter of solution.
m= mol of solute/l of solvent

Question 40

What is the molar fraction?

Answer 40

the ratio of the number of moles to the total number of moles of all components present.

the sum of all mole fractions must equal to 1!

Question 41

How many grams of sodium carbonate (Na2CO3) do we need if one wants to prepare 1.5l (1500ml) of 0.3N solution?

Answer 41

Cn=M/(EV)
E=M/(n* V)
T=Cn*E/1000

Question 42

Calculate the titer of phosphoric acid (H3PO4) solution if one knows that Cn=0.25 N gE/L.

Answer 42

T=CnE/1000
E=MH2PO4/31=32.65

3*1

Question 43

What is normality concentration (Cn) of calcium hydroxide if 40ml of 0.1N of acetic acid (Ca(OH)2 was used to titrate 80 ml of Ca(OH)2 solution