ostwald's theory of indicators

Học thuật
Thân thiện
Definition

Noun: - (Chemistry): A theory in chemistry proposing that all acid-base indicators are either weak acids or weak bases. The theory explains color change based on ionization: the color of the ionized (dissociated) form of the indicator molecule is different from the color of its non-ionized (undissociated) form.

Usage
  • Scientific Explanation: Used to describe the fundamental chemical mechanism behind how pH indicators function.
    • According to Ostwald's theory of indicators, phenolphthalein is colorless in its undissociated acidic form and pink in its ionized basic form.
    • The color change of litmus paper can be explained by Ostwald's theory of indicators.
Advanced Usage
  • "in the context of Ostwald's theory": Used to frame a discussion or analysis of an indicator's behavior specifically within this theoretical model.
    • In the context of Ostwald's theory, the endpoint of a titration corresponds to the point where the indicator's ionized and unionized forms are present in equal concentrations.
Variants and Related Words
  • Ostwald's Dilution Law (n): A related principle by the same scientist, Wilhelm Ostwald, which relates the dissociation constant of a weak electrolyte to its degree of dissociation and concentration.
  • Indicator Theory (n): A more general term for the conceptual framework explaining how indicators work, of which Ostwald's theory is a specific and historically important example.
Synonyms
  • Ionization Theory of Indicators: A synonymous name for the same concept, emphasizing the role of ionization in the color change.
Related Concepts
  • Acid-Base Indicator (n): A substance that changes color depending on the pH of the solution.
  • Dissociation Constant (Ka/Kb) (n): The equilibrium constant for the dissociation of an acid or base, central to the quantitative application of Ostwald's theory.
  • pH (n): A scale used to specify the acidity or basicity of an aqueous solution, which the indicator helps to determine.
Noun
  1. (chemistry) the theory that all indicators are either weak acids or weak bases in which the color of the ionized form is different from the color before dissociation

Từ đồng nghĩa