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phan111 > Non – Aqueous Titration & KJELDAHL Method > Flashcards

Non – Aqueous Titration & KJELDAHL Method Flashcards

1
Q

3 reason why Non – Aqueous Titration use

A
  • Most organic acids and bases are insoluble in water
    ❖ Most organic acids and bases are weak acids and bases
    ❖ Moisture must be avoided or at least limited to 0.05%
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2
Q

Non – Aqueous Titration: Acid titrant

A

Perchloric acid in glacial acetic acid or dioxane

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3
Q

Non – Aqueous Titration: Base titrant

A

Sodium methoxide,
Lithium methoxide in
ethylenediamine, n-butylamine, morpholine

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4
Q

Non – Aqueous Titration: Indicators
ACIDIMETRY - Weak bases

A

common: Crystal violet
malachite green,
quinaldine red,
methylrosaniline

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5
Q

Non – Aqueous Titration: Indicators
ACIDIMETRY - (relatively stronger base)

A

Methyl orange, methyl red, Thymol blue

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6
Q

Non – Aqueous Titration: Indicators
ALKALIMETRY - (weak acids)

A

Azoviolet

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7
Q

Non – Aqueous Titration: Indicators
ALKALIMETRY - (strong acids)

A

Thymol blue

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8
Q

Non – Aqueous Titration: Indicators
ALKALIMETRY - (most preferred)

A

potentiometric methods

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9
Q

A method designed to determine and quantify ammonia in
ammonium sulfate obtained by decomposing organic
substance with sulfuric acid

Nitrogen determination

A

KJELDAHL Method

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10
Q

Standardization in Non-aqueous titration: __________ + Perchloric acid —->__________+_______

A

1: Potassium Hydrogen Phthalate
2: Phthalic acid
3: Potassium Chlorate

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11
Q

KJELDAHL Method: standard sol- H2SO4
Sx + H2SO4 (CUSO4, Se) —> (NH4)SO4 + H2O
formation of Ammonium Sulfate
What step is this ?

A

Step 1: Digestion

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12
Q

KJELDAHL Method: standard sol- NaOH
(NH4)SO4 + NaOH—> NH3 + Na2SO4 + H2O
formation of Ammonia
What step is this?

A

Step 2: Neutralization

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13
Q

KJELDAHL Method: standard sol- H3BO3 (boric acid)
NH3 + H3BO3—–> (NH4)2B4O7+H2O
formation of Diammonium Tetraborate
What step is this?

A

Step 3: Distillation

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14
Q

KJELDAHL Method: standard sol- HCl
(NH4)2B4O7+HCl —-> (NH4)Cl + H3BO3
formation of Ammonium chloride
What step is this?

A

Step 4: Titration

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15
Q

if N is as NO3, _______ is add

A

salicylic acid

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16
Q
  • USP Methods
  • Method I for ________
  • Method II for _______
A

macroanalysis (1)
semimicroanalysis (2)

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17
Q

Kjeldahl set-up

A

heater
Digestion flask (step 1)
Trap [digestion of sample nitrogen converted to ammonia]
Condenser [Distillation of ammonia into a trapping solution]
trapping flask [quantification of the ammonia by titration w/ a standard solution]

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18
Q

% sample = (ml x N) acid - (ml x N) base x meq sample
—————————————— x 100
wt of sample

A

formula for – Acidimetric assay, Nitrogen determination

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19
Q

Nitrogen determination use in ?

A

Protein in food, fertilizer, blood, assays of Heparin,
insulin, urea, povidone

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20
Q

Urea properties:

A

CO(NH2)2
60.06 g/mol
factor : 2

21
Q

Precipitation Method is Also called?

A

Argentometric titration

22
Q

Volumetric methods based on
reactions that yield ionic
compounds of limited
solubility

A

Argentometric titration

23
Q

primary analyte use to find Argentometric titration is ???

A

Chlorine/ Halides

24
Q

Common titrant use in Argentometric titration?

A

Silver Nitrate

25
Q

other name of Silver Nitrate

A

AgNO3
Lapiz infernulariz
indelible ink
caustic pencil
Lunar pencil

26
Q

Old medical use of silver nitrate?

A

neonatal conjunctivitis

27
Q

recent treatment for neonatal conjunctivitis?

A

crede’s prophylaxis

28
Q

crede’s prophylaxis is a combination of what drug?

A

Erythromycin + Tetracycline

29
Q

neonatal conjunctivitis is caused by what kind of bacteria?

A

Neisseria Gonorrhea

30
Q

3 ADSORPTION INIDICATOR

A

DCF: Dichlorofluorescein
Eosin Y: Tetrabromofluorescein
TEE: tetrabromophenolphthalein ethyl

31
Q

types of indicator: takes part in chemical reaction ?
and commonly use in precipitation

A

Internal indicator

32
Q

types of indicator: did not take part in the chemical reaction
and commonly use in neutralization

A

External Indicator

33
Q

what indicator is use in redox method ex: KMnO4

A

self indicating indicator

34
Q

formation of insoluble colored complex
slight excess thiocyanate ion
reacts with ferric ion from
the indicator producing a
faint reddish brown
coloration

  • use HNO3 to acidify the analyte
A

Volhard Method

35
Q

Volhard Method: Volumetric precipitation table

A

1st std : Silver nitrate
VS (2nd std): ammonium thiocyanate
indicator: Ferric Alum -(Fe(NH4)(SO4)2
example: Aminophylline NaCl
end point: faint reddish brown

FeNH4(SO4)2+ 3NH4SCN
Fe(SCN)3 ↓+ 2(NH4)2S

36
Q

Formation of 2nd precipitate
chromate reacts with excess
silver ions forming a
secondary precipitate of
reddish silver chromate

INC Base of the analyte it use “ CaCO3 and NaHCO3”

INC Acid of the analyte it use CH3COOH

A

Mohr Method

37
Q

Mohr Method: Volumetric precipitation table

A

1st std : Sodium Chloride (NaCl)
VS (2nd std): Silver nitrate
indicator: Potassium chromate (K2CrO)
example: SLS
end point:
reddish silver chromate

AgNO3 + K2CrO4 à AgCrO4 ↓+
KNO

38
Q

COLORED ADSORPTION PRODUCT
change in color precipitate.

used as indicator in the titration of
potassium chloride with standard silver
nitrate solution.
❖ silver chloride (ppt)formed is
negatively charged due to adsorbed
chloride ion and the indicator exists in
the solution with a greenish yellow
❖ Direct titration with silver nitrate solution

slight excess of silver ion is adsorbed by the silver chloride
precipitate colloid particles became positively charged which
adsorb the fluoresceinate ions forming a reddish pink
adsorption product

A

Fajan Method

39
Q

Fajan Method: Volumetric precipitation table

A

1st std : Sodium Chloride (NaCl)
VS (2nd std): Silver nitrate
indicator: DCF, Eosin Y, TEE
example: Phenylephrine HCl and Tubocuraine
end point:
reddish pink

40
Q

Gay-Lussac: Volumetric precipitation table

A

1st std : Sodium Chloride (NaCl)
VS (2nd std): Silver nitrate
indicator: None
example: NaCl
cessation of precipitation

41
Q

Liebig: Volumetric precipitation table

A

1st std : potassium biphthalate
VS (2nd std): Sodium tetraphenyl Boron
indicator: Bromophenol blue
example: Organic N Compounds
appearance of turbidity.

42
Q

neonatal conjunctivitis is also called ?

A

ophthalmia neonatorum

43
Q

USP requirements of Ammonium Bromide?

A

99.5% - 100.5%

44
Q

USP requirements of Zinc Oxide?

A

95% - 98%

45
Q

USP requirements of acetic acid?

A

2%-5%

46
Q

factor of AgBr, KBr, BaCl2, Hg?

A

AgBr: 1
KBr: 1
BaCl2: 2
Hg: 2

47
Q

Substances assayed: mainly used for determination of
__________and some compounds
that form insoluble products (ppt) with AgNO3

A

halides (Cl-, Br- & I-),
SCN-(thiocyanate),
CN- Cyanide
Heavy Metals: Hg

48
Q

Primary standard of Precipitation Assay?

A

sodium chloride

49
Q

Standardization of ____Silver nitrate
(concentration)

A

0.1 Normality

phan111 (9 decks)

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