Definition of Distribution Law: The distribution law, also known as Nernst’s distribution law, states that when a solute is distributed between two immiscible solvents at a constant temperature, the ratio of its concentrations in the two solvents is constant. $\frac{[\text{Solute}]_A}{[\text{Solute}]_B} = K_d$ $[\text {Solute}] _A \quad \text{and} \quad [\text {Solute}] _B$ are the concentrations of … Read more
Definition: The temperature at which two partially miscible liquids become fully miscible (UCST) or fully immiscible (LCST). Upper Critical Solution Temperature (UCST): Below this temperature, the liquids are completely miscible. Lower Critical Solution Temperature (LCST): Above this temperature, the liquids are completely miscible. Characteristics: Phase Transition Point: Represents the temperature at which the nature of … Read more
Definition of Partially Miscible Liquids: Two liquids that dissolve into each other in limited amounts, forming two separate layers beyond a certain concentration. Characteristics of Partially Miscible Liquid: Phase Separation: At certain concentrations and temperatures, these liquids separate into two distinct phases, each enriched in one of the components. Concentration Limits: The limits of miscibility … Read more
Solubility of liquids in liquids refers to the ability of one liquid to dissolve in another. It depends on polarity—polar liquids mix with polar, and nonpolar with nonpolar. Binary Solutions: Binary Solutions: Solutions composed of two components (e.g., ethanol and water). Miscibility: The ability of two liquids to mix in any proportion. Types of Miscibility: … Read more
Fick’s Laws of Diffusion Principles in Biological Systems : First Law: States that the rate of diffusion is proportional to the concentration gradient. Describes the flux of molecules $J = -D \frac{dC}{dx}$ J is the flux; D is the diffusion coefficient $\frac{dC}{dx}$ , is the concentration gradient Second Law: Explains that diffusion causes changes in … Read more
Henry’s Law in Solubility of Gas in Liquids: The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. This relationship is expressed by Henry’s Law: $C = k_H \cdot$ Where: C is the concentration of the gas in the liquid. kH is Henry’s Law … Read more
Solvation & association Solvation & association is the process of surrounding solute particles with solvent molecules, leading to the formation of a solution. It involves: Breaking Solute-Solute Interactions: Energy is required to separate solute molecules from each other. Breaking Solvent-Solvent Interactions: Energy is needed to create space within the solvent by disrupting solvent-solvent interactions. Formation … Read more
A Quantitative Approach to Factors Influencing Solubility of Drugs solubility involves analyzing how physicochemical properties and environmental conditions affect dissolution. Key Factors Influencing Solubility: Physicochemical Properties: Molecular Size and Structure: Larger molecules typically have lower solubility. Polarity and pKa: Polar drugs and ionized forms are more soluble in water; the Henderson-Hasselbalch equation determines ionization. Partition … Read more
Ideal solubility parameters provide a quantitative measure of the solubility of substances. They are based on the concept that similar intermolecular forces between solute and solvent lead to better solubility. The most common parameter is the Hildebrand solubility parameter (δ), which is defined as: $\delta = \sqrt{\frac{\Delta H_v – RT}{V_m}}$ Where: ΔHv = Enthalpy of … Read more
Solute-Solvent Interactions & Solubility is largely determined by the interactions between solute and solvent molecules. Steps Involved in the Dissolution of a Solute Detachment of Solute Particles: Solute particles separate from the bulk solute. Requires energy to overcome intermolecular forces. Formation of Vacant Sites in Solvent: Solvent molecules rearrange to create vacant sites. These sites … Read more
