Non-Aqueous Titrations Overview
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Questions and Answers

What happens to a substance if it is more acidic than the solvent?

  • It remains neutral.
  • It behaves as a base.
  • It reacts violently.
  • It behaves as an acid. (correct)

    • Water has a high dissociation constant (Ks) and a high autoprotolysis.

    False

    What should a substance be to be effective in a solvent?

    soluble

    Acetic acid has a ______ dissociation constant and ______ autoprotolysis.

    <p>low, low</p> Signup and view all the answers

    What type of titrant is used for standardization of acetic HCIO?

    <p>Potassium Acid Phthalate</p> Signup and view all the answers

    Match the following samples with their corresponding titrants:

    <p>Loratadine = HClO4 in glacial acetic acid Amino acids = HClO4 in glacial acetic acid Methyldopa = HClO4 in glacial acetic acid Acetic acid = Potassium acid phthalate</p> Signup and view all the answers

    The presence of a strong acid titrant allows the suppression of the carboxylic group.

    <p>True</p> Signup and view all the answers

    What indicator is used for titration with HClO4 in glacial acetic acid?

    <p>Crystal violet</p> Signup and view all the answers

    Formic acid is characterized by having ______ dissociation and ______ autoprotolysis compared to acetic acid.

    <p>high, high</p> Signup and view all the answers

    What is the role of the solvent when the substance is more basic?

    <p>It behaves as an acid.</p> Signup and view all the answers

    What is the purpose of refluxing with acetic anhydride in the analysis of tertiary amines?

    <p>To acylate primary and secondary amines</p> Signup and view all the answers

    In the reaction of salicylaldehyde, secondary amines react similarly to primary amines.

    <p>False</p> Signup and view all the answers

    What is the role of sodium methoxide in the titration of acidic samples?

    <p>It acts as a titrant.</p> Signup and view all the answers

    The indicator used for titration with sodium methoxide is __________.

    <p>thymol blue</p> Signup and view all the answers

    Match the following compounds with their respective properties:

    <p>Allopurinol = Weak acid + water insoluble Barbiturates = Weak acids + water insoluble Sulphonamides = Weak acid + low water solubility Acetic anhydride = Used for acylating amines</p> Signup and view all the answers

    Which amine classification is determined by titration with standard acetous HClO4?

    <p>Tertiary amines</p> Signup and view all the answers

    The endpoint detection in the titration of a mixture of mineral and carboxylic acids is conducted using potentiometry.

    <p>True</p> Signup and view all the answers

    What differentiating effect does methyl isobutyl ketone have when used as a solvent?

    <p>It differentiates between mineral and carboxylic acids.</p> Signup and view all the answers

    E1 represents the total amines, while E2 represents the __________ amines.

    <p>tertiary</p> Signup and view all the answers

    Which of the following is NOT a property of weak acids in the given analysis?

    <p>High water solubility</p> Signup and view all the answers

    What is a primary reason for using non-aqueous titrations?

    <p>To determine very weak acids or bases accurately</p> Signup and view all the answers

    Non-aqueous titrations can only be performed in water.

    <p>False</p> Signup and view all the answers

    What is the leveling effect in non-aqueous titrations?

    <p>The ability of solvent to increase strength of weak acids/bases to become strong acids/base.</p> Signup and view all the answers

    In non-aqueous titrations, the conjugate base is formed when the acid loses a ______.

    <p>proton</p> Signup and view all the answers

    Match the acids/bases with their definitions:

    <p>Conjugate Acid = Species created when the base accepts a proton Conjugate Base = Ion remaining after the acid has lost a proton Weak Acid = An acid that does not fully dissociate in solution Strong Acid = An acid that completely dissociates in solution</p> Signup and view all the answers

    Which of the following is NOT an advantage of non-aqueous titrations?

    <p>Lower costs than aqueous titrations</p> Signup and view all the answers

    The differentiating effect refers to a solvent's ability to make all acids behave the same way.

    <p>False</p> Signup and view all the answers

    Name one disadvantage of using non-aqueous titrations.

    <p>Expensive, volatile, or toxic.</p> Signup and view all the answers

    Bronsted theory relates the _____ of a substance to the solvent used.

    <p>acidity/alkalinity</p> Signup and view all the answers

    Which solvent is mentioned as having a differentiating effect in non-aqueous titrations?

    <p>Acetic Acid</p> Signup and view all the answers

    Study Notes

    Non-Aqueous Titrations

    • Titrations performed in a medium without water, utilizing non-aqueous solvents.

    Reasons for Non-Aqueous Titrations

    • Solubility: Some substances insoluble in water are soluble in non-aqueous solvents.
    • Weak Acids/Bases: Determination of very weak acids or bases is not accurate in aqueous solutions due to a lack of distinct endpoints.

    Aim of Non-Aqueous Titrations

    • Increase Dissociation: To increase the dissociation of weak acids and bases, facilitating their behavior as strong acids and bases.
    • Solvent Selection: Non-aqueous solvents are used instead of water.
    • Acid-Base Concepts: Study of acid-base concepts (e.g., Brønsted) using non-aqueous solvents is important.

    Advantages of Non-Aqueous Titrations

    • Pharmacopeial Methods: Many pharmaceutical methods rely on non-aqueous titrations.
    • Insoluble Substances: Useful for substances that are not soluble in water.
    • Weak Species: Applicable for determining very weak acids or bases.
    • Mixed Samples: Useful with mixtures of weak acids or bases with similar dissociation constants.

    Disadvantages of Non-Aqueous Titrations

    • Cost: Non-aqueous titrations are typically more expensive.
    • Volatility: Some non-aqueous solvents are volatile.
    • Toxicity: Certain solvents are toxic.

    Acid-Base Theories

    • Arrhenius Theory: Acids dissociate to produce H+ ions, and bases dissociate to produce OH- ions.
    • Brønsted-Lowry Theory: Acids donate protons (H+), and bases accept protons.
    • Lewis Theory: Electron-pair acceptors are acids, and electron-pair donors are bases.

    Solvent Properties Affecting Titration

    • Autoprotolysis Constant (Ks): The smaller the Ks, the more complete the reaction. Solvents with smaller Ks are usually better for complete reactions.
    • Dielectric Constant (D): The ability of a solvent to separate ions; higher D values result in more complete reactions.
    • Acidic/Basic Character of Solvent: The solvent's character will have an effect on the behavior of acids or bases.

    Types of Solvents used in Non-Aqueous Titration

    • Aprotic: Do not have H atoms on O or N, cannot accept or donate protons. Examples: carbon tetrachloride, benzene.
    • Protogenic: Can accept protons, do not undergo autoprotolysis. Examples: formic acid, glacial acetic acid.
    • Protophilic: Can donate protons, do not undergo autoprotolysis. Examples: ammonia, ethylene diamine.

    Indicators in Non-Aqueous Titrations

    • Crystal Violet, Azo Violet, and Thymol Blue are common indicators used. Their colors change with the pH of the solution (basic or acidic medium).

    Standardization of Titrants

    • Acidic titrants are often standardized against potassium acid phthalate or other suitable materials.
    • Basic titrants such as sodium methoxide are standardized against benzoic acid.

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    Non-Aqueous Titrations PDF

    Description

    Explore the principles and applications of non-aqueous titrations. This quiz covers the reasons for choosing non-aqueous solvents, their advantages, and their relevance in acid-base chemistry. Understand how these titrations play a crucial role in various pharmaceutical methods.

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