Physical Pharmacy Semi-Finals Quiz

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Questions and Answers

What characteristic do weak acids and bases share that affects their solubility?

Their solubility depends on the pH of the medium. (correct)

They only dissolve in non-polar solvents.

Their solubility does not vary with temperature.

They are soluble in all solvents.

What is the relationship described by Henry's Law?

Decreased pressure increases gas solubility.

Increased pressure increases gas solubility. (correct)

Increased temperature decreases gas solubility.

Gas solubility is independent of pressure.

How can the solubility of a substance be enhanced according to the content?

By reducing the temperature of the solution.

By adding more non-polar solute.

By increasing the solvent's polarity.

By manipulating the pH of the solution. (correct)

What does 'like dissolves like' mean in the context of solubility?

Polar solutes dissolve only in polar solvents. Signup and view all the answers

What is a saturated solution?

A solution that cannot dissolve any more solute at a given temperature. Signup and view all the answers

How does particle size affect solubility?

Smaller particles increase the surface area, enhancing solubility. Signup and view all the answers

What defines the solubility of a substance?

The maximum amount of solute that can be dissolved in a given temperature and amount of solvent. Signup and view all the answers

Which of the following contributes to a solution being classified as unsaturated?

Contains less solute than can dissolve at a given temperature. Signup and view all the answers

What is the definition of solubility in physical pharmacy?

The maximum amount of a solute that can dissolve in a solvent. Signup and view all the answers

Which component dissolves the solute in a solution?

Solvent Signup and view all the answers

What characterizes a saturated solution?

It reaches a point where no more solute can dissolve. Signup and view all the answers

What is a supersaturated solution?

A solution that has dissolved more solute than is normally possible. Signup and view all the answers

In drug formulation, why is understanding solubility important?

It affects drug delivery and absorption. Signup and view all the answers

What does the Noyes-Whitney equation describe?

The transfer of molecules from solid to solution. Signup and view all the answers

What is the formula for solubility?

Solubility = amount of solute / volume of solvent Signup and view all the answers

Which statement is true regarding the role of water in pharmaceutical applications?

Water is the primary solvent due to its biocompatibility. Signup and view all the answers

What distinguishes colloidal particles in terms of size from coarse dispersions?

Colloidal particles range from 1 nm to 0.5 μm. Signup and view all the answers

Which of the following best describes the Faraday-Tyndall effect?

The scattering of light by particles in a colloidal dispersion. Signup and view all the answers

What is a defining characteristic of amphiphilic colloids?

They possess two distinct regions with opposing solution affinities. Signup and view all the answers

Brownian motion in colloidal systems is observable under which condition?

When observed through an ultra microscope. Signup and view all the answers

Which of the following substances represents a true colloid?

Colloidal silver. Signup and view all the answers

How does diffusion in colloidal systems occur?

Particles spontaneously move from higher to lower concentration until equilibrium is reached. Signup and view all the answers

What size range defines coarse dispersions?

Greater than 0.5 μm. Signup and view all the answers

What role does the solvent sheath play around colloidal particles?

It stabilizes particles against precipitation. Signup and view all the answers

What effect does temperature generally have on the solubility of most substances?

Solubility increases with rising temperature. Signup and view all the answers

What is a characteristic of molecular dispersion in a dispersed system?

It forms a homogeneous solution of multiple components. Signup and view all the answers

How does the presence of salts generally affect the solubility of substances?

Salting out decreases solubility while salting in increases it. Signup and view all the answers

Which statement is true regarding gases and temperature effects on solubility?

Gases typically become less soluble as temperature increases. Signup and view all the answers

What defines a lyophobic dispersion?

It consists of materials that have little attraction to the dispersion medium. Signup and view all the answers

Study Notes

Equilibrium Solubility

Equilibrium solubility can be altered by changing external conditions, such as temperature.
Solutions with more solute than the equilibrium solubility are unstable.
Cooling a solution typically leads to crystallization of excess solute.

Unsaturated Solutions

These solutions contain less solute than the maximum amount that can dissolve at a given temperature.
Additional solute can still dissolve in unsaturated solutions.

Factors Affecting Solubility

pH of Solutions:
- Many drugs are weak acids or bases; their solubility often depends on the pH of the medium.
- Ionized drugs are generally more soluble in aqueous environments than their unionized forms.
Nature of Solute and Solvent:
- The principle "Like dissolves like" applies; polar solutes dissolve in polar solvents, while non-polar solutes favor non-polar solvents.
Pressure:
- For gases, increased pressure boosts solubility, as described by Henry's Law.
Temperature:
- Usually, solubility increases with temperature, except for gases, where it commonly decreases.
Particle Size:
- Smaller particles have larger surface areas which can enhance dissolution rates and solubility.
Presence of Salts:
- Salting Out: Presence of salts can decrease solubility.
- Salting In: Inclusion of salts can occasionally enhance solubility.

Types of Solutions

Saturated Solutions:
- No additional solute can dissolve at specific temperature and pressure. Represents the maximum solute concentration.
Supersaturated Solutions:
- Contains more solute than what can typically dissolve; these are metastable and can precipitate excess solute.

Components of Solutions

Solute:
- The substance that is dissolved (e.g., drugs, salts).
Solvent:
- The medium that dissolves the solute (commonly water in pharmaceuticals due to biocompatibility).

Dissolution

Describes the transfer of molecules from a solid state into solution, often evaluated through the Noyes-Whitney Equation.

Classifications of Dispersed Systems

Molecular Dispersion (True Solutions):
- Composed of components with particle sizes less than 1 nm (e.g., oxygen, glucose).
Colloidal Dispersion:
- Intermediate particle size (1 nm to 0.5 μm), examples include colloidal silver.
Coarse Dispersion:
- Larger particles (>0.5 μm) such as grains of sand and red blood cells.

Properties of Colloids

Optical Properties:
- Exhibit the Faraday-Tyndall Effect, scattering light and altering its polarization.
Kinetic Properties:
- Show Brownian motion where colloidal particles move continuously, demonstrating diffusion until equilibrium is achieved.

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Description

Test your knowledge on equilibrium solubility and the effects of various conditions like temperature on solute dissolution. This quiz is designed for 2nd-year BS Pharmacy students at Arellano University during their semi-finals. Prepare to deepen your understanding of physical pharmacy concepts relevant to real-world applications.