Farmasi Fisik : Kelarutan fase dalam zat cair

Summary

In this lecture, the focus is on solubility across different phases, including gases in liquids, liquids in liquids, and solids in liquids. Key concepts such as Henry’s Law and Raoult's Law are introduced, alongside practical examples demonstrating calculations for solubility and distribution coefficients. The discussion highlights the factors influencing solubility and the distinction between ideal and non-ideal solutions. Emphasizing the significance of these principles in pharmaceuticals, the lecture illustrates how understanding solubility aids in drug formulation and effective delivery.

Takeaways

• 😀 Takeaway 1: The lecture focuses on the solubility of various phases, continuing from previous discussions on solutions.
• 😀 Takeaway 2: Gas solubility in liquids is defined as the concentration of gas in a solution at equilibrium with the pure gas.
• 😀 Takeaway 3: Henry's Law is fundamental for calculating gas solubility, expressed as C2 = kH * P.
• 😀 Takeaway 4: An example illustrates how to calculate the amount of oxygen dissolved in water under specific temperature and pressure conditions.
• 😀 Takeaway 5: Liquid-liquid solubility is explored through the mixing of solvents, relevant to pharmaceutical formulations.
• 😀 Takeaway 6: The distinction between ideal and non-ideal solutions is made based on the interactions of solute and solvent particles.
• 😀 Takeaway 7: An example is given to demonstrate calculations related to the heat of vaporization in liquid-liquid solubility.
• 😀 Takeaway 8: Solid solubility in liquids is explained with reference to ideal and non-ideal conditions, including an example using naphthalene.
• 😀 Takeaway 9: The distribution of solutes between immiscible solvents is quantified using partition coefficients.
• 😀 Takeaway 10: The lecture emphasizes the practical applications of solubility principles in pharmaceuticals and related fields.

Q & A

What is the primary focus of the lecture on solubility?

The primary focus is on understanding solubility in various contexts, particularly the solubility of gases, liquids, and solids in pharmaceutical applications.

How does Henry's Law relate to gas solubility in liquids?

Henry's Law states that the concentration of a gas dissolved in a liquid at equilibrium is proportional to the partial pressure of that gas above the liquid, expressed by the formula C2 = ΣP.

What is the difference between ideal and non-ideal solutions?

Ideal solutions follow Raoult's Law with no significant heat exchange during mixing, while non-ideal solutions deviate from this law, exhibiting heat exchange and other interactions.

What factors influence the solubility of a substance in a solvent?

Factors include temperature, pressure, the nature of the solute and solvent, and interactions between them.

What is the formula for calculating the solubility of solids in liquids?

The formula is X2 = ΔHf / (2.303RT), where X2 is the mole fraction of the solute, ΔHf is the molar heat of fusion, R is the gas constant, and T is the absolute temperature.

How is pH related to the solubility of weak acids and bases?

The solubility of weak acids and bases is influenced by pH, with certain equations available to calculate the pH at which maximum solubility occurs for these substances.

What role do electrolytes play in solubility?

Electrolytes, particularly weak acids and bases, have solubility that can be significantly affected by the pH of the solution, influencing their degree of dissociation.

What is the distribution coefficient and how is it calculated?

The distribution coefficient (K) describes the ratio of a solute's concentration in two immiscible phases and is calculated as K = C1 / C2, where C1 and C2 are the concentrations in each phase.

Provide an example of calculating gas solubility using Henry's Law.

An example calculation might involve determining how many grams of oxygen can be dissolved in water at a certain temperature and pressure, using the known solubility coefficient.

What practical applications of solubility concepts are mentioned in the lecture?

Practical applications include the formulation of pharmaceuticals, understanding drug solubility and stability, and optimizing drug delivery methods.