Titrations

Question 1

What is a titration

Answer 1

Lab method used for quan analysis

Question 2

Why titration

Answer 2

Determine unidentified concentrations of known analyte

Question 3

Volumetric analysis

Answer 3

Volume measurement

Question 4

Titrant

Answer 4

Slow addition of one solution of known concentration

Question 5

Why in pharmacy

Answer 5

Content analysis of active ingredients/ drugs and raw materials can be performed easily quickly reproducible and accurate

Question 6

Pharmaceutical applications

Answer 6

Pharm compounds are weak acids/bases that can be analysed by aqueous/ non aqueous titration

Eg salicylic acid/ caffeine
Amino acids

Assay of drugs- weak chromophore

Question 7

Karl fischer titration

Answer 7

Find water content
Based on oxidation reaction of iodine and sulphur
Endpoint when all water used up

Question 8

Volumetric titration

Answer 8

Suitable to determine water content down to 1 %
End point potentiometrically

Question 9

Coulometric determination

Answer 9

Endpoint detected electrochemically

Question 10

How do pharm use titration

Answer 10

Determine unknown of chem in blood and urine
Development of new pharmaceutical
Determine fat content water and vitamins

Question 11

Titrant

Answer 11

Reagent of known standard concentration added ro solution containing analyte
We measure its volume
(In the burrette)

Question 12

Analyte

Answer 12

Solution of unknown
In beaker

Question 13

Role of Indicator

Answer 13

Added to analyte solution to indicate end point by change in colour

Question 14

Equivalence point

Answer 14

Mixture with stoichiometrically equivalent amount of titrant and analyte

Question 15

End point

Answer 15

Point in titration when we stop adding titrant

Question 16

Titration error

Answer 16

Error due to difference between end point and the equivalence

Question 17

Acid base titration

Answer 17

Acidic or basic titrant reacts with an analyts thats is a base or an acid

Question 18

Complexometric titration

Answer 18

Metal/ligand reaction

Question 19

Redox titrations

Answer 19

Oxidising or reducing titrants reacts with an analyte

Question 20

Precipitation titration

Answer 20

Titrant reacts with an analyte to form a precipitate

Question 21

Back titration/ reverse titration

Answer 21

endpoint hard to identify
Excess volume another reactant with known conc

excess titrated

Question 22

What is an Acid base titration used for

Answer 22

Used for analysis of organic compounds eg pharmaceuticals/ agricultural/ and environment labs
Kjedahl method

Question 23

Primary standard

Answer 23

Pure and stable chemical compounds used to standardise the standard solution in titration

Question 24

Standardisation of acidic and basic titrants

Answer 24

Standardising achieved by titrating known volume of titrants with other titrant of EXACT concentration

Question 25

How does phenophthalein work

Answer 25

Weak acid which dissociates in water forming pink anions

Question 26

How do Acid base indicators work

Answer 26

Weak acids bases Dissolved in water dissociates slightly and form ions

Question 27

Equilibrium in acid and alkaline conditions

Answer 27

Acid left Alkaline right

Question 28

Titration curve

Answer 28

Graph showing progress of titration as a function of volume of titrant added

Question 29

Requirements for acid base titration

Answer 29

Substances react quickly and completely in precise stoichiometric quantities

Question 30

Amount of solute in moles

Answer 30

Conc in mol/dm3 X Volume dm3

Question 31

Molarity (base) x volume (base) =

Answer 31

Molarity (acid) x volume (acid)

Question 32

Complexometric titration

Answer 32

Complexation reaction between analyte and titrant

Question 33

What is a comp recation limited to

Answer 33

Metals that only form a single stable complex Based on lewis/base reaction

Question 34

Example of complexo reaction

Answer 34

EDTA forming a strong 1:1 complex with many metal ions

Question 35

Use of complexo in pharma

Answer 35

Determine metal content of drugs

Question 36

EDTA

Answer 36

Provides e- and has 6 binding sites Forma stable metal ligand complex 1:1 stoichiometry

Question 37

Limitation of EDTA

Answer 37

EDTA complex less stables as ph decreases and end point less distinct

Question 38

Properties of Metal ion indicator

Answer 38

Compound changes colour when binding to a metal ion MUST bund weaker than EDTA + Release metal ion to EDTA

Question 39

Determination of endpoint in complexo titrations with EDTA

Answer 39

Metal ion indicator Mercury electrode Ph electrode Ion selective electrode

Question 40

What is redox reaction based on

Answer 40

Oxidaton/ reduction between analyts and titrant

Question 41

Redox titration indicators

Answer 41

Diphenylamine

Question 42

Monitor for redox

Answer 42

Electrochemical potential

Question 43

Pharma analysis for redox

Answer 43

Determine conc of VLGH in pure medicines and tablets

Question 44

Precipitation titration

Answer 44

Analyt + titrant form insoluble precipitate

Question 45

Mohr method

Answer 45

Cl- using AG as titrant = reddish Ag2CrO = end point

Question 46

What can precipitation in a reaction be used as

Answer 46

Visual indicator Determine salt content in water

Question 47

Back titration

Answer 47

no suitable sensor available / too slow for direct practical titration

Question 48

Process of back titration

Answer 48

Volumetric analysis EXCESS reagent added Unreacted reagent determined by titration = amount of substance in original test solution to be calculated

Question 49

Pharm analysis of back titration

Answer 49

Determine amount if acetylsalicylic acid in aspirin

Question 50

Positives of titrimetric analysis

Answer 50

Precise and accurate Robust and reasonable priced equipment Manual or automated analysis Cheap

Question 51

Limitations of titrimetric analysis

Answer 51

Non selective Time consuming Large amount of sample Analyte must be reactive