1: Chemical Principles
- Page ID
- 367703
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Background to chemical principles involved in the isolation and identification of cations from mixtures are described. Solubility of ionic compounds in water and the solubility variation by common ion effect, pH effect, coordination complex formation, and redox reaction are described in relation to the selective precipitation or dissolution of salts of the cations.
- 1.1: Solubility
- Solubility, i.e., the ability of a substance to form a solution, its related terminologies, and the solubility guidelines for the dissolution of ionic compounds in water are described.
- 1.2: Solubility equilibria
- The solubility equilibrium constant (Ksp), i.e., the equilibrium constant of the dissociation reaction of ionic compounds in water and selective precipitation by adding a reagent that precipitates one of the dissolved cations or a particular group of dissolved cations but not the others are described.
- 1.3: Varying solubility of ionic compounds
- Varying the solubility of ionic compounds based on Le Chatelier's principle is described, specifically by using the common ion effect, the effect of pH, complex ion formation, and redox reactions.
- 1.4: pH Buffers
- A pH buffer is an aqueous solution consisting of a weak acid and its conjugate base or vice versa, which minimizes pH change when a small amount of a strong acid or a strong base is added to it.
- 1.5: Separation of cations in groups
- Cations commonly found in water are separated into five groups by adding suitable reagents that selectively precipitate a set of cations. Group I is separated as insoluble chlorides, group II as sulfides in acidic medium, group III as hydroxides and sulfides in basic medium, group IV as carbonates, and group V remains soluble in this process