Non-aqueous titration is a powerful analytical method essential for the analysis of many pharmaceutical substances. For B.Pharm students, understanding this technique is crucial because it allows for the accurate quantification of very weak acids and bases that are insoluble or do not give sharp end points in aqueous media. This quiz covers the principles, solvents, titrants, and applications of non-aqueous titrations in pharmaceutical analysis.
- Non-aqueous titrations are performed for substances that are:
- Strong acids or bases
- Highly soluble in water
- Very weak acids or bases, or insoluble in water
- Colored compounds
- Which of the following is the most commonly used titrant for the estimation of weak bases in non-aqueous titrations?
- Sodium hydroxide
- Hydrochloric acid
- Perchloric acid
- Sodium methoxide
- A solvent that is capable of donating a proton is known as:
- Aprotic
- Protophilic
- Protogenic
- Amphiprotic
- In the non-aqueous titration of ephedrine HCl, what is the purpose of adding mercuric acetate?
- To act as an indicator
- To precipitate the ephedrine base
- To remove the halide ion as unionized mercuric chloride
- To buffer the solution
- Which indicator is commonly used for non-aqueous acidimetric titrations?
- Phenolphthalein
- Methyl orange
- Crystal violet
- Eosin
- Glacial acetic acid is a popular solvent for titrating weak bases because it is a:
- Leveling solvent for bases
- Differentiating solvent for bases
- Protophilic solvent
- Aprotic solvent
- The titration of weak acids in a non-aqueous medium is known as:
- Non-aqueous acidimetry
- Non-aqueous alkalimetry
- Redox titration
- Complexometric titration
- A solvent that can act as both a proton donor and acceptor is called:
- Protogenic
- Protophilic
- Aprotic
- Amphiprotic
- Which of the following is an example of an aprotic solvent?
- Glacial acetic acid
- Pyridine
- Benzene
- Ethanol
- Which titrant is commonly used in non-aqueous alkalimetry?
- Perchloric acid
- Tetrabutylammonium hydroxide
- Acetic acid
- Hydrochloric acid
- A protophilic solvent is a:
- Proton donor
- Proton acceptor
- Neither a donor nor an acceptor
- Both a donor and an acceptor
- The end point in non-aqueous titrations can be determined by:
- Visual indicators
- Potentiometry
- Both A and B
- Temperature change
- Why must moisture be strictly avoided in non-aqueous titrations?
- Water is a strong acid and interferes.
- Water is a weak base and can compete with the analyte.
- Water causes the indicator to precipitate.
- Water is an aprotic solvent.
- The estimation of sodium benzoate is an example of:
- Non-aqueous acidimetry
- Non-aqueous alkalimetry
- Aqueous titration
- Redox titration
- What is the role of acetic anhydride when preparing perchloric acid titrant in glacial acetic acid?
- To act as a catalyst
- To remove excess water
- To increase the acidity
- To act as a primary standard
- Which of the following is a suitable solvent for the titration of weak acids?
- Glacial acetic acid
- Dimethylformamide (DMF)
- Chloroform
- Carbon tetrachloride
- Crystal violet indicator shows which color change at the end point in an acidimetric titration?
- Yellow to blue
- Colorless to pink
- Violet to blue-green
- Red to yellow
- The strength of a weak base is enhanced in which type of solvent?
- Aprotic
- Protogenic
- Protophilic
- Neutral
- Perchloric acid is a very strong acid when dissolved in:
- Water
- Liquid ammonia
- Glacial acetic acid
- Benzene
- Which of the following would be titrated using non-aqueous alkalimetry?
- Ephedrine HCl
- Sodium chloride
- Phenobarbital
- Pyridine
- A solvent that does not donate or accept protons is:
- Amphiprotic
- Protogenic
- Protophilic
- Aprotic
- The purpose of using a non-aqueous solvent is to:
- Increase the solubility of the drug.
- Enhance the acidic or basic properties of the analyte.
- Both A and B.
- Decrease the solubility of the drug.
- The titration of a weak base with perchloric acid in glacial acetic acid is an example of:
- Non-aqueous alkalimetry
- Non-aqueous acidimetry
- Precipitation titration
- Complexometric titration
- Thymol blue is a common indicator for:
- Non-aqueous acidimetry
- Non-aqueous alkalimetry
- Strong acid-strong base aqueous titrations
- Redox titrations
- Which of these is an example of a protophilic solvent?
- Sulphuric acid
- Pyridine
- Benzene
- Acetic anhydride
- The leveling effect of a solvent refers to its ability to:
- Make all acids or bases appear to have the same strength.
- Allow acids or bases of different strengths to be distinguished.
- Increase the solubility of all substances equally.
- Maintain a constant pH.
- Which of the following is standardized using potassium hydrogen phthalate?
- Sodium methoxide solution
- Perchloric acid solution
- Sodium hydroxide solution
- Hydrochloric acid solution
- Differentiating titration is possible in a solvent that is:
- Aprotic
- A leveling solvent
- A differentiating solvent
- Amphiprotic
- Which of the following statements about non-aqueous titrations is true?
- They are only used for inorganic substances.
- They require specialized glassware resistant to organic solvents.
- They are insensitive to temperature changes.
- They are less accurate than aqueous titrations.
- In the assay of ephedrine HCl, the substance being titrated behaves as a(n):
- Acid
- Base
- Salt of a weak acid
- Salt of a strong base
- What is the function of a solvent like glacial acetic acid in the titration of a weak base?
- It suppresses the basicity of the analyte.
- It enhances the basicity of the analyte by converting it to a stronger base.
- It acts as an inert medium.
- It precipitates the analyte.
- Potentiometric end-point detection in non-aqueous titrations uses a:
- Platinum electrode
- Dropping mercury electrode
- Glass-calomel electrode system
- Conductivity cell
- The titrant sodium methoxide is typically dissolved in a mixture of:
- Benzene and methanol
- Water and ethanol
- Acetic acid and acetone
- Pyridine and chloroform
- Why are halide salts of weak bases like ephedrine HCl not titrated directly?
- The halide ion is strongly basic.
- The halide ion is weakly basic and competes with the analyte.
- The salt is insoluble in organic solvents.
- The salt is unstable.
- The titration of a mixture of bases with different strengths can be performed using a:
- Leveling solvent
- Differentiating solvent
- Protogenic solvent
- Aprotic solvent
- Which of the following is an amphiprotic solvent?
- Chloroform
- Ethanol
- Formic acid
- Liquid ammonia
- The primary standard used to standardize tetrabutylammonium hydroxide is:
- Benzoic acid
- Potassium hydrogen phthalate
- Sodium carbonate
- Oxalic acid
- The choice of solvent in non-aqueous titrations is critical because it affects:
- The solubility of the sample
- The strength of the acid or base
- The sharpness of the end point
- All of the above
- In non-aqueous acidimetry, the glassware should be:
- Rinsed with water
- Dried thoroughly to remove any trace of moisture
- Cooled to 0°C
- Warmed before use
- A solvent like pyridine would be used in the titration of a:
- Weak base
- Weak acid
- Strong acid
- Strong base
- What is the product when a weak base (B) reacts with glacial acetic acid (CH₃COOH)?
- BH⁺ + CH₃COO⁻
- B + H₂O
- B⁻ + CH₃COOH₂⁺
- No reaction occurs
- Non-aqueous titrations are widely used in pharmacopoeial assays for:
- Vitamins and antibiotics
- Metal ions
- Inorganic salts
- Simple sugars
- The acidity of perchloric acid is greatly enhanced in glacial acetic acid due to the:
- Low dielectric constant of the solvent
- Formation of the onium ion (CH₃COOH₂⁺)
- Aprotic nature of the solvent
- High temperature of the reaction
- Which indicator gives a color change from blue to yellow in non-aqueous alkalimetry?
- Crystal violet
- Methyl red
- Thymol blue
- Phenolphthalein
- Which of the following could be a source of error in non-aqueous titrations?
- Presence of moisture
- Temperature fluctuations
- Presence of carbon dioxide
- All of the above
- What is the role of the titrant in a non-aqueous titration?
- To dissolve the sample
- To react quantitatively with the analyte
- To act as the indicator
- To buffer the solution
- To enhance the acidity of a very weak acid, one should use a:
- Protogenic solvent
- Protophilic solvent
- Aprotic solvent
- Neutral solvent
- In potentiometric titrations, the end point is determined by the:
- Point of maximum color change
- Point of maximum potential change for a small volume of titrant added
- Point where the solution becomes neutral
- Point where precipitation begins
- Which of the following is NOT a requirement for a non-aqueous solvent?
- It must be reactive with the titrant.
- It must dissolve the analyte.
- It must be pure and inert to the reactants under titration conditions.
- It should allow for a sharp end point.
- The main advantage of perchloric acid as a titrant is that:
- It is a primary standard.
- Its perchlorate salts are generally soluble.
- It is non-hygroscopic.
- It is a weak acid.
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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