Nonaqueous titrimetry

Question 1

advantages of nonaqueous titrimetry

Answer 1

poor solubility
Weak raectivity

Question 2

Avoid moisture?

Answer 2

does not produce sharp end-point

Question 3

Temperature is controlled?

Answer 3

organic solvents - coefficient of expansion or increase in volume due to temperatures

Question 4

Have both aciditic and basic properties

Answer 4

Amphiphrotic

Question 5

Neither acidic or basic

Answer 5

Aprotic

Question 6

But not acidic, most are extremely weak bases (nonionizable)

Answer 6

Basic

Question 7

Do not possess the acidic or basic properties, weaker acids and bases can be titrated in them

Answer 7

Inert solvents

Question 8

water

Answer 8

amphiprotic

Question 9

Ethanol

Answer 9

Amphiprotic

Question 10

methanol

Answer 10

amphiprotic

Question 11

benzene

Answer 11

aprotic

Question 12

carbon tetrachloride

Answer 12

aprotic

Question 13

ether

Answer 13

basic

Question 14

ketones

Answer 14

basic

Question 15

pyridine

Answer 15

basic

Question 16

The solvent used is?

Answer 16

perchloric acid in Glacial acetic acid

Question 17

Most acidic acid

Answer 17

perchloric acid in Glacial acetic acid

Question 18

Preparation of Perchloric acid in Glacial acetic acid

Answer 18

8.5 mL or perchloric acid
500 mL of GAA
21 mL acetic acid
Stand for 1 day for the excess acetic anhydride to be combined and determine the water content

Question 19

true or false: acetic acid is a string proton acceptor

Answer 19

false, does not compete effectively with weak bases for protons

Question 20

Acetic acid is protonated only by

Answer 20

very strong acids

Question 21

Strongest of the common acids in acetic acid solution

Answer 21

Perchloric acid

Question 22

Added to remove water from aqueous perchloric acid

Answer 22

Acetic anhydride

Question 23

True or False: Weak bases compete very effectively with acetic acid
for protons

Answer 23

true

Question 24

• Titration medium commonly used in nonaqueous
  titration

Answer 24

Perchloric acid in acetic acid

Question 25

very weak indicators are used such as

Answer 25

Oracet blue, quinalidine red, crystal violet,
methylrosaniline chloride, naphtholbenzein, malachite
green

Question 26

Corrects for any moisture in the glacial acetic acid
that reacts with the perchloric acid

Answer 26

Blank Determination

Question 27

Nonaqueous alkalimetry: Solvent

Answer 27

Alcohol or an aprotic solvent, ethylenediamine

Question 28

Nonaqueous alkalimetry: Typical titrants

Answer 28

Lithium methoxide in methanol

Tetrabutyl ammonium hydroxide in dimethylformamide

Question 29

Solvent: Lithium Methoxide in Methanol (0.02N) Preparation:

Answer 29

• 0.12 g Lithium metal
• 150 mL methanol (used to dilute to 1L)

Question 30

Nonaqueous alkalimetry:

Standardization: Lithium Methoxide in Methanol (0.02N)
Primary standard? with blank determination?

Answer 30

Primary standard: 100 mg benzoic acid
With blank determination

Question 31

Nonaqueous alkalimetry: Lithium Methoxide in Methanol (0.02N) Endpoint detection

Answer 31

• Thymol blue, thymolphthalein, azo violet, p-
  hydroxyazobenzene
• Potentiometrically

Question 32

Nonaqueous alkalimetry: Lithium Methoxide in Methanol (0.02N) Blank Determination

Answer 32

Accounts for any water in the solvent which will react
with the methoxide ion

Question 33

Nonaqueous alkalimetry: Employed in the assay of the following:

Answer 33

• Barbiturates
• Uracil
• Sulphonamides

Question 34

Nonaqueous acidimetry: employed in the assay of the following

Answer 34

• Adrenaline
• Amitriptyline.HCl
• Metronidazole
• Propranolol HCl
• Codeine
• Lidocaine HCl
• Chlorhexidine acetate
• Neostigmine bromide
• Chlorpromazine HCl
• Pancuronium bromide

Question 35

Direct titration of alkalimetry

Answer 35

• Assay of Hydrochloric Acid
• Assay of Diluted Phosphoric Acid
• Assay of Boric Acid
• Assay of Tartaric Acid