Pharmaceutical Analytical

Chemistry / PHC 213

Course syllabus:

Acid _ base titration ( 2 labs )Precipitimetric titration ( 1 lab)Complexmetric titration (1 lab)Redox(oxidation-reduction) titration ( 2 lab )

Analytical Chemistry

is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials

Analytical chemistry answer two important questions

What is it ??(Qualitative analysis)

gives an indication of the identity of the chemical species in the sample

How much is it ?? (quantitative analysis) determines the amount (concentration) of one or more of the components in the sample

Classification of Analytical Methods:

Gravimetric method

Volumetric method

Instrumental methods

Gravimetric method:

Gravimetric methods of analysis are based on the measurement of mass.

(:Volumetric method (Titration

involves the addition of a reactant to a solution being analyzed until some equivalence point is reached

Types of Titration:

Acid _ base titrationPrecipitimetric titrationComplexmetric titrationRedox(oxidation-reduction) titration

Instrumental methods :

Spectrophotometry

Chromatography

Application of Analytical Chemistry :

Analytical chemistry play an important role in nearly all aspect of chemistry

Medicine IndustryEnvironmentalFood and AgricultureQuality control

Application of Analytical Chemistry:

In medicine, analytical chemistry is the basis for clinical laboratory tests which help the physicians diagnose disease

In industry, analytical chemistry provides the means of testing the raw materials for assuring the quality of finished products whose chemical composition is critical (eg. Drugs )

The nutritional value of food

determined by chemical analysis for major component such as protein and carbohydrate and trace components such as vitamins and minirals

Definition of some terms:

Sample: is a material that we wish to analyze Analyte: is the substance or element in the sample whose

presence or concentration we wish to determine titrant: is a solution of known concentration which is added

(titrated) to another solution to determine the concentration of second chemical species

Titration:is a process which is performed

by slow addition of standard

solution "titrant" from a burette to a solution of the analyte until the reaction between the two is complete.

Standard Solution:

- is a solution of known concentration - prepared by dissolving a known amount of the

substance (primary standard substance)in a known volume of liquid

- They provide a reference to determine unknown concentrations

-Two types,, primary and secondary standard solution

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Standard solution

1-Must be easily obtained in very high

grade of purity and of known composition.

2-Very stable, and resists reactions with air

( non-hygroscopic )

3- It is recommended to have high equivalent weight to minimize weighing error.

4- It must react with other substances in quantitative way according to balanced chemical equations (stoichiometry)

Primary standard Secondary standard

1-The concentration of which can’t be directly calculated from the weight of the solute and volume of the solution. 2- The exact concentration is determined by:

- Titration against a primary standard solution

Examples:

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Standard solution

potassium acid phthalate, oxalic

acid, benzoic acid, sulphamic acid.

Borax, sodium carbonate.

Potassium dichromate, potassium bromate and potassium iodate.

Sodium oxalate, arsenious oxide, and potassium ferrocyanide.

Primary standard Secondary standard

Hydrochloric acid, sulphuric acid.

Sodium hydroxide, ammonia

Potassium permanganate

Acids

Bases

Oxidizing agents

Reducing agents

Volume difference between the equivalence point and the end point should be small .

This difference in volume is the titration error

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End point:

Equivalence point:

The point in a titration when a physical change occurs that is associated with the condition of chemical equivalence.

The point in a titration when the amount of added standard reagent is exactly equal to ( is chemically equivalent to) the amount of the analyte.

Detection of the end point

Indicator :a substance that indicate the presence, absence, or

concentration of another substance ,,often used in a titration to indicate the point at which the reaction is complete by means of a characteristic change, especially in color

such as: litmus paper in acid media in base media

Methods of expressing concentration of standard solutions

Molar solution: It is a solution of the substance containing one mole (gram

molecular weight) of the substance per one liter of solution.

Molarity (M) : It is the number of moles (gram molecular weight )of solute

per one liter of solution.

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I-Molarity

Some useful algebraic relationships:

M = no. moles solute V( L) No. of moles = M x V ( L ) No. of moles = wt.solute, g fwt

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M=MolarityV=volume in liter

Fwt= formula weight or molecular weight ( g)

Examples:

Example 1:Calculate the molarity of 17g Na2CO3 in 500ml of solution (fwt=106)

Example 2: ( HOME WORK)Calculate the weight in grams of Na2CO3 required to prepare 250ml of 0.15M solution. (fwt=106)

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Convert 500 ml to liter by ÷1000 = 0.5 L

II. Normal solution: It is the solution that contains one gram equivalent weight

of solute per liter of solution.

Normality (N) : It is the number of equivalents (gram equivalent weight) per

liter of solution.

If the equivalent weight = formula weight

so, N = M

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II-Normality

Normality (N) = Number of equivelant weight Volume(V) in (Liter) No.of eq.wt = N x V(L)

OR \ No.of eq.wt = weight of solute (g) equivalent weight (Eq.wt)

Eq.wt = Formula weight (F.wt ) n (no. of (H+) OR (OH-) )

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N=nM

N=Normalityn = number of (H+) or (OH-)M= Molarity

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Problem??? Calculate the eq.wt for each of the following: HCl , H2SO4 , H2CO3 , H3PO4 , Ba(OH)2

*In case of Ba(OH)2 Ba(OH)2 2 OH- eqwt = fwt / 2

*In case of HCl or NaOH

HCl 1 H+ eqwt = fwt / 1NaOH 1 OH-

*In case of H3PO4

H3PO4 H2PO4- + H+

eqwt = fwt / 1

H3PO4 HPO4-2 + 2 H+

eqwt = fwt / 2

Examples:

1-How much primary standard potassium acid phthalate, KHC8H4O4, is required to prepare 499.5 ml of 0.10 N solution?(fwt = 204.23)

Weight ( g)?? =

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Convert 499.5 ml to Liter by ÷1000 = 0.4995 L

TYPES OF WATER USED:

• Distilled water: is water that has many

of its impurities removed through distillation

• Deionized water : is water that has had

all minerals removed from it,as cations like sodium, calcium, iron, and copper, and anions such as chloride and sulfate, using an ion exchange process

Lab glassware and equipment

burette

Pipette:

Graduated pipettes Volumetric pipettes

beaker

cylinder

funnels

Volumetric flask

Conical flask:

Glass stopper conical flask Conical flask

Glass rod

Mortar and pestle

Hot plate

electronic balance

hood

GENERAL GUIDELINES:

1- When first entering the lab , do not touch any equipment, chemicals, or other materials in the laboratory area until you are instructed to do so

2- Follow all written and verbal instructions carefully. If you do not understand a direction or part of a procedure, ASK YOUR TEACHER BEFORE PROCEEDING WITH THE ACTIVITY

3- Never work alone in the laboratory,No student may work in the laboratory without the presence of the teacher

4- Do not eat food, drink beverages, or chew

gum in the laboratory,Do not use laboratory glassware as containers for food or beverages

5- Observe good housekeeping

practices , Work areas should be kept clean at all times

7 -Labels and equipment instructions

must be read carefully before use

8 -Keep hands away from face, eyes, mouth, and body while using chemicals , Wash your hands with soap and water after performing all experiments

9-you should Know the locations and operating procedures of all safety equipment

CLOTHING:

Dress properly during a laboratory activity. Long hair must be tied back, Shoes must

completely cover the foot

HANDLING CHEMICALS:

1- All chemicals in the laboratory are to be considered dangerous. Avoid handling chemicals with fingers , Do not taste or smell any chemicals

2- Check the label on all chemical bottles twice before removing any of the contents

3- Never return unused chemicals to their original

container, and Never remove chemicals or other materials from the laboratory area

HANDLING GLASSWARE AND EQUIPMENT:

1- Never handle broken glass with your hands , Place broken glass in the sharps container

2- Examine glassware before each use

3- Never look into a container that is being heated4- hood (how can we use it in the safe way )