Pharm Ana part II Finals

Neutralization Reaction

Neutralization Reaction

Are Chemical processes in which an acid (protom donor) reacts with a base (proton acceptor).

Water and Salt

These are the products of neutralization reaction in aqueous solution?

Neutralization reaction

The reaction between acid and a base is called?

Neutralization titration

Acid-base titration is also called as?

Acidimetry

A specialized analytical technique used to determine the strength of an acid

Alkalimetry

A special analytical technique we can use to determine the strength of a base or an alkaline compound

Acidimetry

It is the reaction between a standard acid having known concentration and a base having an unknown concentration in the presence of a suitable indicator

Alkalimetry

It is the reaction between a standard base or a alkaline compound having a known concentration and an acid having an unknown concentration in the presence of a suitable indicator

Acidimetry

The tendency of an acid to dissociate forming protons and an anion

Alkalimetry

The tendency of a base to accept protons from another chemical species

Acidimetry

The determination of base by using a standard acid

Alkalimetry

The determination of an acid using a standard base

Amphoteric

Since water can behave as a weak base or a weak acid, what is the term used for it?

Non-Aqueous titration

This procedure is very useful because it satisfies two different requirements namely - suitable titration of very weak and bases along with providing a with an ability to dissolve organic compounds.

Bronsted-lowry theory and it's definition of acids and bases.

Many reactions which occur in non-Aqueous titration procedures can be explained via what theory?

A base (to which a proton can be donate) is present

Potentially acidic substances can behave as acids only when?

An Acid (from which a proton can be accepted) is present

Potentially basic substance can behave as bases only when?

• It is impossible to tirate for a mix of acids or bases

• It is impossible to titrate for a mix of strong and weak acids (bases)

• It is impossible to titrate separately for a mix of acids (bases) with near constants of dissociation.

• It is impossible to define substance which are insoluble in water

Titration in water solution is limited by factors:

Aprotic solvents

These solvents are:

• neutral in charge

• are chemically inert.

• generally have a low dielectric constant

Protogenic solvents

These solvents are:

• more acidic in characters

• tend to have a leveling effect on the bases they come in contact with

Protophilic solvents

These solvents:

• Have a basic character

• tend to react with the acids they come in contact with, leading to the formation of solvated protons

Amphiprotic solvents

These solvents have the properties which are protophilic and protogenic.

Crystal Violet

•considered the most common indicator in the titration of the bases.

• used as 0.5%w/v solution in glacial acetic acid

• color change from violet to blue to greenish yellow

Quinaldine red

• employed as indicator in the determination of the drug substance in dimethylformide (DMF)

• It is used as 0.1%w/v solution in ethanol

Thymol Blue

• used as 0.2%w/v solution in methanol.

• the color change is from yellow to blue.

• used as an indicator for the titration of substances acting as acids in DMF.

Suitable pH indicator

Must be chosen to detect the endpoint of the titration. The color changes or other effect should occur close to the equivalence point of the reaction.

Neutral (pH=7)

A strong acid will react with a strong base to form a?

Acidic (pH<7) solution

A strong acid will react with a weak base to form a?

Basic (pH>7) solution

A weak acid will react with a strong base to form a?

(1) To determine the endpoint in neutralization process

(2) To determine hydrogen-ion concentration or pH

(3) To indicate that a desired change in pH has been affected

Indicators are complex organic compounds used:

Litmus - Blue

Phenolphthalein - Pink

Methyl orange - yellow

Screened methyl orange - orange

Bromothymol blue - Blue

Wood ash, soap solution, ammonia solution, sodium hydroxide

Litmus - red

Phenolphthalein -colorless

Methyl orange - red

Screened methyl orange - purple

Bromothymol blue - orange

Hydrochloric acid, Sulphuric(VI)acid and lemon juice

Litmus - colorless

Phenolphthalein - colorless

Methyl orange - red

Screened methyl orange - orange

Bromothymol blue - orange

Distilled water and sodium chloride

Litmus - blue

Phenolphthalein - Pink

Methyl orange - yellow

Screened methyl orange - orange

Bromothymol blue - Blue

Sour milk, toothpaste and calcium hydroxide

Acid - Yellow

Base - blue

Bromocresol green, bromophenol blue and bromothymol blue

Acid - yellow

Base - purple

Bromocresol purple

Acid - yellow

Base - Red

Cresol red

Acid - yellow

Base - Violet

Cresol red-Thymol blue TS

Acid - Yellow

Base - Green

Malachite green

Acid - Red

Base - Yellow

Methyl red and Methyl Yellow

Acid - Red-Violet

Base - Green

Methyl red-Methylene Blue TS

Acid - colorless

Base - Red

Phenolphthalein and Quinaldine red

Acid - Yellow

Base - Red

Phenol Red

Acid - Yellow

Base - Blue

Thymol blue

Acid - Colorless

Base - Blue

Thymolphthalein

1. Dichlorofloresein TS

2. Eosin Y

3. Ferric ammonium Sulfate TS

4. Potassium Chromate TS

5. Sodium Alizarin TS

6. Tetrabromophenolphthalein TS

7. Tetrabromophenolphthalein, Ethyl Ester TS

Indicator employed in precipitation

1. Azo-Violet

2. Crystal violet TS

3. Malachite green

4. Methyl red

5. Methyl violet

6. p-Naphtholbenzein

7. Phenol red

8. Quinaldine Red

9. Thymol blue

Indicators for Non-Aqueous titration

1. Diphenylamine

2. Dithizone(Diphenylthiocarbazone)

3. Eriochrome black

4. Methyl red

5. Hydroxynaphthol blue

6. Murexide

7. Naphthol green

8. 1-(2-Pyridylazo)-2-napthol

Indicators for complexometric Titration