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Pharm Ana LAB > (Prelim) POST-LAB > Flashcards

(Prelim) POST-LAB Flashcards

1
Q

a.k.a. as Volumetric Analysis

A

Titrimetric Methods of Analysis

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2
Q

analytical method in which the volumes of a
solution of known concentration consumed during an analysis is taken as a measure of the amount of active constituent in a sample being analyzed

A

Titrimetric Methods of Analysis

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3
Q

Types of Chemical Reactions in
Titrimetric Analysis

A
  1. Neutralization (acid-base) in aqueous and
    nonaqueous solvents.
  2. Oxidation-reduction
  3. Precipitation
  4. Complexation
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3
Q

HCl + NaOH → NaCl + H2O

A

Titrimetric Methods of Analysis

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4
Q

are complex organic compounds used
to:
* determine the end point in neutralization
process,
* determined hydrogen-ion concentrations pH, or
* indicate that a desired chance in pH has been
affected.

A

INDICATORS

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4
Q

Requirements of Titrimetric Methods of Analysis

A
  • Reaction must proceed to completion, that is, the chemical equilibrium constant K must be equal to or greater than 108
  • The reaction must proceed in a stoichiometric manner
  • A suitable end-point-directing device must be available
  • For direct titrimetric methods the reaction must be rapid so a sharp end point is desirable.
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5
Q

used to sharpen up the color
change.

A

MIX INDICATORS

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6
Q

Rules for the Use of Indicators

A
  1. Use 3 drops of indicator test solution for a titration unless otherwise directed.
  2. When a strong acid is titrated with a strong alkali, or a strong alkali with a strong acid, methyl orange, methyl red, or phenolphthalein may be used.
  3. When a weak acid is titrated with a strong alkali, use phenolphthalein as the indicator.
  4. When a weak alkali is titrated with a strong acid, use methyl red as the indicator.
  5. A weak alkali should never be titrated with a weak acid, or vice versa, since no indicator will give a sharp end point
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7
Q

Malachite green

A

pH Range: 0.0 – 2.0
Acid: Yellow
Base: green

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8
Q

Methyl yellow

A

pH Range: 2.9 – 4.0
Acid: Red
Base: Yellow

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9
Q

Bromophenol Blue

A

pH Range: 3.0 – 4.6
Acid: Yellow
Base: Blue

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9
Q

Bromocresol green

A

pH Range: 4.0 – 5.4
Acid: Yellow
Base:Blue

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9
Q

Methyl orange

A

pH Range: 3.2 – 4.4
Acid: Pink
Base: Yellow

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10
Q

Methyl red

A

pH Range: 4.2 – 6.2
Acid: Red
Base:Yellow

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10
Q

Bromothymol blue

A

pH Range: 6.0 -7.6
Acid: Yellow
Base: Blue

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11
Q

Phenolphthalein

A

pH Range: 8.0 – 10.00
Acid: Colorless
Base: Red

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12
Q

usually contains varying amount of
moisture and NaHCO3

A

Na2CO3

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12
Q

1L of 1N HCl should contain 34.6g or 1 equiv

A

1N Hydrochloric Solution

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12
Q

Concentrations of standard solutions can be
expressed in terms of NORMALITY (mEq/mL), MOLARITY (moles/L), and MOLALITY (moles/Kg)

A

Standard Solutions

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12
Q

Primary Standard of 1N Hydrochloric Solution

A

Na2CO3/tromethamine

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13
Q

Indicator of 1N Hydrochloric Solution

A
  • methyl red TS – permanent pink end point
  • Bromocresol green TS – pale yellow end point
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14
Q

A diprotic acid, 1000mL of 1N solution should
contain 98.08g/2 = 49.04g

A

1N H2SO4

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15
Q

95% solution has a SG of 1.83 at 25ºC

A

1N H2SO4

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16
Q

Standardization of 1N H2SO4

A
  • Against tromethamine
  • Against NaOH using phenolphthalein
  • Gravimetric precipitation using Ba(OH)2
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17
Q

Acid Solutions

A
  1. 1N Hydrochloric Solution
  2. 1N H2SO4
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18
Q

Alkali Solutions

A

1N NaOH

19
Q

is hygroscopic

A

NaOH

20
Q

Solutions with carbonate is treated with methyl red

A

1N NaOH

21
Q

1 mol or 204.23g of pure dried potassium
biphthalate is 1 equiv

A

1N NaOH

22
Q

titrant used is acid and the analyte used is an acid

A

Alkalimetric Analysis

23
Q

conducted by introducing a standard alkali solution gradually from a burette into a solution of the acid being assayed until chemically equivalent amounts of each have reacted as shown by some change in
properties of the mixture.

A

Direct Titrations

24
Q

a.ka. Back Titration

A

Residual Titration

25
Q

used when ever the end point of a direct titration deviates appreciably from the stoichiometric points for some reason; e.g, when the acidic sample is insoluble in water and rate of its reaction with the standard
base is relatively slow.

A

Residual Titration – a.ka. Back Titration

26
Q

when the substance to assayed does not give a distinct, sharp end point with an indicator by direct titration.

A

Residual Titration – a.ka. Back Titration

27
Q

Assay of Hydrochloric Acid

A

Direct Alkalimetric Titration

28
Q

Official requirement for concentrated HCl

A

36.5% - 38%

29
Q

Official requirement for diluted HCl

A

9.5g – 10.5g/100mL

29
Q

Assay of Salicylic Acid

A

Direct Alkalimetric Titration

30
Q

Materials in Assay of Salicylic Acid

A
  • 0.1 N NaOH VS
  • Dilute Ethanol
  • Phenolphthalein TS
31
Q

Chemical Reaction Involved in Assay of Salicylic Acid

A

C7H6O3 + NaOH → NaC7H5O3 + H2O

32
Q

USP Limits of Assay of Salicylic Acid

A

99.5 – 101%

33
Q

Titer value of Assay of Salicylic Acid

A

13.81 mg

34
Q

Salicylic Acid formula

A

C7H6O3

35
Q

USP Limits in Assay of Aspirin

A

99.7 – 100.5%

36
Q

Assay of Aspirin

A

Residual Alkalimetric Titration

37
Q

Materials In Assay of Aspirin

A
  • 0.5 N NaOH VS and 0.5 N H2SO4 VS
  • Phenolphthalein TS
38
Q

Titer value in Assay of Aspirin

A

45.05 mg

39
Q

titrant used is acid and the analyte used is a base.

A

Acidimetric Analysis

40
Q

Assay of Sodium Bicarbonate
Tablets

A

Direct Acidimetric Titration

41
Q

Chemical Reaction Involved in Assay of Sodium Bicarbonate Tablets

A

2NaHCO3+H2SO4 → Na2SO4 + 2H2O + 2CO2

41
Q

USP Limits in Assay of Sodium Bicarbonate
Tablets

A

95 – 105%

42
Q

Materials in Assay of Sodium Bicarbonate
Tablets

A
  • 1 N Hydrochloric Acid VS
  • Methyl Red
43
Q

Assay of Zinc Oxide

A

Residual Acidimetric Titration

44
Q

Materials in Assay of Zinc Oxide

A
  • 1 N H2SO4 VS and 1NaOH VS
  • Ammonium Chloride
  • Methyl orange TS
45
Q

Chemical Reaction Involved in Assay of Zinc Oxide

A

ZnO + H2SO4 → ZnSO4 + H2O

45
Q

Nitrogen Determination by Kjeldahl
Method

A

a. Method I
b. Method II

46
Q

USP Limits in Assay of Zinc Oxide

A

98 – 100.5%

47
Q

a macro method in which the ammonia
is distilled into excess boric acid solution.

A

Method I

48
Q

it is used if nitrates or nitrites are not present

A

Method I

49
Q

one gram of sample is used.

A

Method I

50
Q

2-3 milligram of sample is used.

A

Method II

50
Q

a semi micromethod in which smaller samples are employed using a semi micro Kjeldahl apparatus.

A

Method II

51
Q

nitrogen is first liberated by acid digestion

A

Method II

Pharm Ana LAB (2 decks)

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