(F) Gravimetric method of analysis

Question 1

Based on measuring the mass of a pure compound though which the analyte is chemically related.

Answer 1

Gravimetric Analysis

Question 2

analyte is separated from solution of sample as a precipitate converted to a compound of known composition that can be weighed.

Answer 2

Precipitation Gravimetry

Question 3

analyte is separated from other constituents by conversion to gas, and the weight of the gas is used as a measure of analyte concentration

for substances thar evaporate or are volatile

Answer 3

volatilization gravimetry

Question 4

analyte is separated by deposition on an electrode via electrical current

Answer 4

Electrogravimetry

Question 5

changes in physical and chemical properties of materials are measured as a function of increasing temperature or as a function of time

Answer 5

Thermogravimetry

Question 6

T of F : You’re supposed to wash colloidal precipitates like crystalline precipitates

Answer 6

F you do NOT wash them because peptization occurs

Question 7

The conversion of precipitate into colloidal solution by adding a suitable electrolyte

Answer 7

peptization

Question 8

T or F : it is not ideal to have low solubility in a precipitate

Answer 8

false it is ideal so that your precipitate won’t dissolve as you are filtering it

Question 9

T or F : it is ideal that your precipitate is free of contaminants and be bigger in size

Answer 9

T

Question 10

T or F : The more reactive your precipitate is the better

Answer 10

False it is better if it is stable and unreactive with the constituents of the atmosphere

Question 11

The net effect of these variables that determine the particle size can be accounted for relating the particle size to a single property

Answer 11

relative supersaturation by von weimarn, 1925

Question 12

unstable solution that contains a higher solute concentration than a
saturated solution. As excess solute precipitates with
time, supersaturation decreases to zero.

Answer 12

supersaturated solution

Question 13

T or F : if Ksp > Qsp = precipitation will not happen

Answer 13

F it will

Question 14

T or F : If supersaturation decreases to zero, precipitation
will also stop.

Answer 14

T

Question 15

measure of the solute’s
supersaturation.

Answer 15

Q - S
Q= concentration of the solute
Idk what the S is i cant find it sorry

Question 16

T or F: The relationship between the value of RSS and the
particle size is DIRECTLY PROPORTIONAL. As the
value of RSS increases, the particle size decreases, and
vice versa.

Answer 16

F (inversely)

Question 17

process of forming smaller particles or colloidal
particles.

Answer 17

NUCLEATION.

Question 18

T or F: The RSS value is BIG . A solution must have a low
supersaturation which would mean that the precipitate will be larger in terms of the particles.

Answer 18

F (its smol like my brein)

Question 19

The initial formation process in which
a minimum number of atoms, ions, or molecules join
together to give a stable solid.

Answer 19

NUCLEATION

Question 20

2 types of nucleation

Answer 20

sponataneous and induced

Question 21

The subsequent growth after
nucleation. It means building of nuclei over each other
which will eventually form a crystalline solid.

Answer 21

PARTICLE GROWTH:

Question 22

are precipitants that creates complex
ions.

Answer 22

(Complexing
agents

Question 23

happen when you add
an organic precipitant in the solution and
creates complexes with the metallic ion.

Answer 23

Complex ions

Question 24

metallic ion will be
part of the central atom/structure of the
precipitate and around the central atom/metallic ion, there will negative charges
contributed by the organic complexing agent.
It increases solubility of precipitate as well.)

Answer 24

Complexes

Question 25

T or F : We use a concentrated solution in a precipitating process

Answer 25

False we dont

Question 26

Tor F; To decrease Q , we use the homogeneous precipitation technique

Answer 26

T

Question 27

This is when particles collide but do not interact. It is not affected by gravity.

Answer 27

Brownian movement

Question 28

does not settle out of solution due to its size and Brownian movement

Answer 28

Colloids

Question 29

Accumulation and building up

Answer 29

coagulation

Question 30

same as coagulation but involves a combination of a larger froup of different ions/ atoms with each other

Answer 30

Agglomerate

Question 31

T or F: coagulation may be hastened by cooling, digestion and adding an electrolyte

Answer 31

F (it will be hastened by heating in a water bath, stirring, and adding an electrolyte)

Question 32

T or F :Colloids are stable due to being either a negative and positively charged particles

Answer 32

T

Question 33

components of electric double layer

Answer 33

primary adsorption layer and counter ion layer

Question 34

a layer in the electric double layer that consists mainly of adsorbed silver ions

Answer 34

primary

Question 35

A process in which a substance (gas, liquid, or solid) is held on the surface of a solid.

Answer 35

ADSORPTION

Question 36

A process in which a substance within the pores of a solid.

Answer 36

ABSORPTION

Question 37

a layer in the electric double layer that contains sufficient excess of negative ions (principally nitrate) to just balance the charge on the surface of the particle.

Answer 37

counter - ion layer

Question 38

T or F : as colloid particles approach each other, the electric double layer produces an electrostatic force, preventing panicles from adhering or colliding

Answer 38

T

Question 39

measure of repulsive force that particle exerts on like particles in the solution

Answer 39

Effective charge (q)

Question 40

T or F : More diluted means that there is more distance for forces of agglomeration

Answer 40

F less distance

Question 41

T or F : Increased heat decreases absorbed ions

Answer 41

F increases

Question 42

these are bigger particles, easily filtered and are purer

Answer 42

Crystalline

Question 43

T or F : Crystalline formation can be improved significantly by minimizing Q and maximizing S in the RSS value or von weirman equation

Answer 43

T

Question 44

T or F: effective charge should be reduced to zero to increase repulsive forces, making it easier to coagulate

Answer 44

F (decreases repulsive force)

Question 45

main cause of impurities - process where normally soluble compounds are carried out of solution by a precipitate and may result in impurities and / or contamination

Answer 45

coprecipitation

Question 46

process where a foreign compound precipitates on top of the desired precipitate

Answer 46

post precipitation

Question 47

major source of contamination in coagulated colloids du to impurity being chemically or physically adsorbed on the surface of precipitates

Answer 47

surface adsorption

Question 48

T or F: by using volatile electrolytes, this increases surface adsorption

Answer 48

false decrease

Question 49

occurs when exchange of two ions that have the same charge, roughly about the same size (>5%), belongs to the same crystal class

Answer 49

mixed crystal formation

Question 50

T or F: changing to a more selective precipitating agent reprecipitation minimizes mixed crystal formation

Answer 50

T

Question 51

Greatest type of co-precipitation ni which a compound (freign ions in the counter-ion layer) is physically trapped within a precipitate during rapid precipitate formation

Answer 51

Occlusion

Question 52

A type of co-precipitation in which coprecipitates physically trap a pocket of solution within a precipitate during rapid precipitate formation.

Answer 52

Mechanical Entrapment

Question 53

process which a precipitate is formed by slow generation of a precipitating reagent homogeneously throughout a solution (therefore excesses do not occur)

Answer 53

Homogeneous Precipitation

Question 54

T or F : Solids formed by homogeneous precipitation are purer but smaller in size

Answer 54

F (larger)

Question 55

complexing agent, increasing purity and decreases the unwanted compounds / contaminants

Answer 55

urea

Question 56

reagents that form coordination compounds and prevents formation of unwanted side products

Answer 56

chelating agents

Question 57

special type of ligand that can form multiple bonds to the metal ion resulting to a highly stable compound, highly colored coordination

Answer 57

chelates

Question 58

bonds to the central metal ion, donates electrons to the metal ion (chelating agents)

Answer 58

ligands

Question 59

creates complexes / chelates with nickel ion normally forms red complex solution (cherry red) light green to dark red precipitate can be enhanced by turning it slightly basic (add basic solns 8-10)

Answer 59

Dimethylglyoxime