Physical Pharmacy Practice Questions

Physical Pharmacy Practice Questions

This document contains questions and answers for a Physical Pharmacy exam, focusing on the topics of colloidal systems, absorption, surfaces, and reaction kinetics.

Part 1: Colloidal Systems

• Question 1: What is the size range of the dispersed particles in a colloidal system?

• Answer: From 10^-7 to 10^-5 cm

• Question 2: A cubic particle has a side length of 1 cm², which gives a surface area of 6 cm². If we divide the particles into smaller cubes with side lengths of 0.01 cm, what is the total surface area?

• Answer: 600 cm²

• Question 3: What is the coagulation threshold?

• Answer: The minimum concentration of electrolyte required to cause coagulation at a stable rate.

• Question 4: What are the components of a colloidal micelle?

• Answer: Colloidal core, adsorption layer, diffusion layer.

• Question 5: What factors affect the stability of a colloidal system?

• Answer: The size of the dispersed particles, the charge of the particles, the concentration, and the hydration properties of the colloidal particles.

• Question 6: In the absorption of gases and vapors on solid surfaces, what is absorption?

• Answer: Absorption is the increase in the concentration of gas (vapor) on the surface of the solid phase.

• Question 7: Based on the adsorption force, how many types of adsorption are there?

• Answer: Physical adsorption and chemical adsorption.

• Question 8: What is surface tension?

• Answer: The surface free energy per unit area of a specific surface.

• Question 9: What factor determines the charge of a micelle particle?

• Answer: The potential determining ion.

• Question 10: Arrange the dispersion of three systems: coarse, colloidal, and true solution in ascending order of dispersion.

• Answer: Coarse < colloidal < true solution

• Question 11: Clay suspension particles with a high degree of dispersion in water have a radius of r = 10^-7 m. Knowing the viscosity of the medium η = 6.5.10^-4 N.s/m², T = 313 K. With R = 8.314 mol^-1.K^-1. What is the diffusion coefficient of the colloidal particles?

• Answer: 3.52.10^-12 m²/s

• Question 12: A water droplet has a radius of r = 10^-4 m. Knowing the viscosity of air η = 1.8.10^-5 N.s/m² and neglecting the density of air compared to the density of water, what is the sedimentation rate of the droplet?

• Answer: 12.1.10^-4 m/s

• Question 13: What is the common foaming agent used in toothpaste?

• Answer: Sodium lauryl sulfate

• Question 14: What is the size range of the dispersed particles in a colloidal system?

• Answer: From 10¹ to 10³ Å

• Question 15: A cubic particle has a side length of 1 cm², which gives a surface area of 6 cm². If we divide the particles into smaller cubes with side lengths of 0.001 cm, what is the total surface area?

• Answer: 6000 cm²

• Question 16: When 1 liter of 0.005 M AgNO₃ solution is reacted with 2 liters of 0.001 M KI solution, we get AgI colloid with the following structure:

• Answer: [m(AgI).nAg+.(n-x) NO3-]x+.x NO3-

• Question 17: What is the potential determining ion for the colloid in question 16?

• Answer: Ag+

• Question 18: When adding K₂SO₄ to the colloid in question 16, which ion causes coagulation?

• Answer: SO₄^2-

• Question 19: What is the condition for light to be reflected when passing through a colloidal system, in relation to the wavelength of light (λ) and the diameter of the dispersed particles (d)?

• Answer: λ < d

• Question 20: When light passes through a colloidal system, what is the wavelength (λ) of the light that causes the most scattering?

• Answer: Small

• Question 21: What is the cause of mutual coagulation?

• Answer: The interaction of two types of colloids with opposite charges.

• Question 22: Where do surfactants act?

• Answer: At the interface between phases.

• Question 23: What is the role of CaCl₂ in emulsion phase inversion?

• Answer: N/D emulsifier

• Question 24: Which of the following is not consistent with Langmuir’s adsorption theory?

• Answer: After adsorption is complete, desorption then occurs.

• Question 25: What are the characteristics of a Span surfactant?

• Answer: It is an ester of sorbitan and fatty acids.

• Question 26: What are the roles of surfactants?

• Answer: Emulsification, micelle formation, detergents.

• Question 27: In a coarse system, what is the size of the dispersed particles?

• Answer: > 10^-5 cm

• Question 28: When the dispersed particles in a system have the same or similar shape, what is it called?

• Answer: Monodisperse system

• Question 29: What kind of system is a solution of NaCl completely dissolved in water?

• Answer: Homogeneous system

• Question 30: A cubic particle has a side length of 1 cm², which gives a surface area of 6 cm². If we divide the particles into smaller cubes with side lengths of 10^-4 cm, what is the total surface area?

• Answer: 6.10⁴ cm²

Part 2: Reaction Kinetics

• Question 31: What is a first-order reaction?

• Answer: A reaction whose rate depends on the concentration of one substance and whose half-life is independent of the initial concentration.

• Question 32: Choose the most accurate statement about a simple unimolecular second-order reaction.

• Answer: Simple unimolecular second-order reactions are reactions whose rates depend on the concentration of two substances, with two cases: the initial concentrations are the same and different.

• Question 33: When does the rate constant of a reaction increase?

• Answer: When increasing the reaction temperature, introducing a catalyst into the reaction.

• Question 34: What are the characteristics of a first-order reaction?

• Answer: The half-life T½ = 0.693/k, the time for the substance to lose 10% of its initial amount is T90 = 0.105/k, the half-life does not depend on the initial concentration.

• Question 39: For the reaction I₂(g) + H₂(g) 2HI, it is observed that:

• – If the concentration of H₂ is doubled while keeping the concentration of I₂ constant, the rate doubles.

• – If the concentration of I₂ is tripled while keeping the concentration of H₂ constant, the rate triples.

• What is the rate equation?

• Answer: v = k[H₂][I₂]

• Question 40: For the reaction 2NO(g) + O₂(g) 2 NO₂(g). The experimental expression for the rate of the reaction is: v = k[NO]²[O₂]. Choose the correct statement.

• Answer: The overall order of the reaction is 3.

• Question 41: According to Van’t Hoff’s formula, γ = 3. When the temperature is increased by 100 degrees, how many times does the reaction rate increase?

• Answer: 59049 times

• Question 42: At 150^oC, a reaction finishes in 16 minutes. Calculate the time for the reaction to finish at 800^oC. Knowing that the temperature coefficient of the reaction is 2.5.

• Answer: 163 hours

• Question 43: The radioactive decay of an isotope is a first-order reaction with a half-life t_1/2 = 60 years. How long does it take to decompose 87.5% of the isotope?

• Answer: 180 years

• Question 44: How can the rate of reaction be expressed?

• Answer: It is the change in concentration of reactants over time.

• Question 45: Choose the most accurate statement about a catalyst.

• Answer: A catalyst is a substance that alters the rate of a reaction and does not change in chemical composition when the reaction occurs.

Part 3: AgI colloid

• Question 61: 40 ml of 1.2.10^-4 M AgNO₃ solution is mixed with 20 ml of 3.10^-4 M KI solution, what type of colloid is obtained?

• Answer: Negatively charged

• Question 62: What is the structure of the AgI colloid in question 61 (negatively charged, KI excess)?

• Answer: [m(AgI)n.I-.(n-x)K+]x-.xK+

• Question 63: In the structure of the AgI colloid in question 62: [m(AgI)n.I-.(n-x)K+]x-.xK+, what is the charge of the diffusion layer?

• Answer: Positive

• Question 64: When adding K₂SO₄ to the colloid in question 61, which ion causes coagulation?

• Answer: K+

• Question 65: Which of the following electrolytes has the smallest coagulation threshold for the colloid in question 62: [m(AgI)n.I-.(n-x)K+]x-.xK+?

• Answer: K₂SO₄

• Question 66: When placing the colloid in question 61: negative charge in an electric field, where will the diffusion layer move?

• Answer: Negative

• Question 67: How is the AgI colloid in question 61 prepared?

• Answer: Condensation by double exchange reaction

• Question 69: How many types of stability are usually classified in a colloidal dispersion?

• Answer: Kinetic stability, Aggregate stability.

• Question 70: When is Langmuir’s adsorption equation applicable?

• Answer: For monolayer adsorption

Part 4: Other Questions

• Question 71: Choose the correct statement about homogeneous and heterogeneous reactions.

• Answer: Homogeneous reactions are reactions where the reactants are in the same phase, while heterogeneous reactions are reactions where the reactants are in different phases.

• Question 72: Arrange the particle size of three systems: coarse, colloidal, and true solution in descending order of size.

• Answer: True solution < colloidal < coarse

• Question 73: Based on the properties of the colloidal system, what are the characteristics of gelatin?

• Answer: It is a hydrophilic and reversible colloidal system.

• Question 74: What creates the Helmholtz potential?

• Answer: It is created by the potential determining layer and the counterion layer.

• Question 75: What is the role of water in the preparation of Prussian blue colloid?

• Answer: It is a solvent that helps to wash the Prussian blue precipitate.

• Question 76: The rate constant of a first-order reaction can be expressed by the formula:

• Answer: k = 2.303/t *ln(Ao/A)

• Question 77: Reaction CH₃COOCH₃ + NaOH CH₃COONa + CH₃OH

• The experimental expression for the rate of the reaction is V = [CH₃COOCH₃][NaOH]. Choose the most accurate statement:

• Answer: The reaction is first order with respect to the ester and first order with respect to NaOH.

• Question 78: 20 ml of 0.02 M AgNO₃ solution is mixed with 10 ml of 0.01 M KI solution, what type of AgI colloid is obtained?

• Answer: Positively charged

• Question 79: What will happen when KCl is added to the colloid in question 78?

• Answer: Coagulation

• Question 80: The structure of the AgI colloid in question 78: positively charged colloid has the form:

• Answer: [m(AgI)n.Ag+.(n-x)I-]x+.x NO3-

• Question 81: In the structure of the AgI colloid in question 78: positively charged colloid, what is the charge of the adsorption layer?

• Answer: Negative

• Question 82: When placing the colloid in question 78: positively charged colloid in an electric field, where will the diffusion layer move?

• Answer: Positive

• Question 83: Which of the following substances has the HIGHEST coagulation threshold: NaCl, NaBr, NaI?

• Answer: NaI

• Question 84: Choose the correct statement about the charge of a colloidal particle.

• Answer: A colloidal particle can have a positive or negative charge.

• Question 85: Choose the most accurate statement about the adsorbed substance.

• Answer: The adsorbed substance is the substance that is attracted to the surface of the adsorbent.

• Question 86: How does the dialysis method purify colloid?

• Answer: Ions or small molecules of impurities will move through the dialysis membrane due to osmotic pressure.

• Question 87: What is obtained when Na is evaporated and condensed in a cold organic solvent?

• Answer: Colloid of Na in an organic solvent.

• Question 88: 20 ml of 2.4.10^-4 M AgNO₃ solution is mixed with 10 ml of 6.10^-4 M KI solution, what type of colloid is obtained?

• Answer: Negatively charged

• Question 89: In the structure of the AgI colloid in question 88: Negatively charged, what is the charge of the adsorption layer?

• Answer: Positive

• Question 90: The structure of the AgI colloid in question 88: negatively charged, KI in excess, has the form:

• Answer: [m(AgI)n.I-.(n+x)K+]x-.xK+

• Question 91: When adding NaCl to the colloid in question 88: negatively charged, which ion causes coagulation?

• Answer: Na+

• Question 92: Which of the following electrolytes has the GREATEST coagulation power for the colloid in question 88?

• Answer: Fe₂(SO₄)₃

• Question 94: When placing the colloid in question 88: negatively charged colloid in an electric field, where will the diffusion layer move?

• Answer: Negative

• Question 95: When placing a positive colloid in an electric field, the diffusion layer will move to the positive pole. What is this phenomenon called?

• Answer: Electrophoresis

• Question 96: The AgI colloid in question 88: AgNO₃ + KI colloid is prepared by which method?

• Answer: Condensation by chemical method

• Question 98: What are the characteristics of a Tween surfactant?

• Answer: It is an ester of sorbitan and polyoxyethylene.

• Question 99: When investigating the rate of a reaction at a non-high temperature, how many times does the rate constant increase if the temperature is increased by 20 degrees Celsius?

• Answer: 9 times

• Question 100: In the structure of a colloidal particle, what is ξ?

• Answer: Zeta potential.

• Question 101: What are the differences between physical adsorption and chemical adsorption?

• Answer: The heat of adsorption is small, the adsorbed substance is not changed, the adsorption is reversible.

• Question 102: What type of surfactant is gelatin?

• Answer: It is a natural surfactant.

• Question 103: In the structure of a colloidal particle, what is φ?

• Answer: Thermodynamic potential.

• Question 105: In a homogeneous system, at a constant temperature, what is the rate of reaction?

• Answer: It is proportional to the product of the concentrations of the reactants.

• Question 106: What is obtained when a liquid is dispersed into small liquid droplets in air?

• Answer: Aerosol

• Question 107: Based on the state of aggregation of the phases, what kind of colloidal system is Ruby?

• Answer: S/S

• Question 108: What colloidal system does vitamin C belong to?

• Answer: Molecular solution

• Question 109: What is obtained when a liquid is dispersed in a gas medium?

• Answer: Aerosol

• Question 111: To reduce the energy required during the dispersion method for colloid preparation, what is usually done?

• Answer: Adding a surfactant.

• Question 112: What is the general principle of dialysis in colloid preparation?

• Answer: The electrolytes diffuse through the semipermeable membrane.

• Question 113: Choose the incorrect statement about the diffusion coefficient.

• Answer: It is inversely proportional to the concentration of the dispersed phase.

• Question 114: What does the kinetic properties of a colloidal system include?

• Answer: Brownian motion, diffusion, osmotic pressure, sedimentation.

• Question 115: Choose the incorrect statement about the concentration gradient.

• Answer: When diffusion occurs, the concentration gradient is always constant.

• Question 116: What does the osmotic pressure depend on?

• Answer: Concentration of the dispersed phase.

• Question 117: What is the reason for reducing sedimentation and increasing the kinetic stability of the system?

• Answer: Brownian motion, diffusion, osmotic pressure.

• Question 118: How do colloidal particles move in Brownian motion?

• Answer: It is the zigzag movement of particles smaller than 5 μm.

• Question 122: What happens to the thickness of the diffusion layer when the concentration of the indifferent electrolyte increases?

• Answer: Decreases

• Question 123: What happens to the thermodynamic potential and the zeta potential when the concentration of the indifferent electrolyte increases?

• Answer: The thermodynamic potential remains constant, the zeta potential decreases.

• Question 124: When adding an adsorbed ion with the same sign as the potential determining ion, what happens to the thickness of the diffusion layer?

• Answer: Increases

• Question 125: When adding an adsorbed ion with the same sign as the potential determining ion, what happens to the thermodynamic potential and the zeta potential?

• Answer: The thermodynamic potential and the zeta potential increase.

• Question 126: When adding an adsorbed ion with the same sign as the potential determining ion until the zeta potential reaches the limiting value, what happens to the thermodynamic potential?

• Answer: Decreases

• Question 126: When adding an adsorbed ion with the opposite sign to the potential determining ion, what happens?

• Answer: Electrical neutralization occurs between the adsorbed ion and the potential determining ion.

• Question 127: When adding an adsorbed ion with the opposite sign to the potential determining ion, what happens?

• Answer: Both the zeta potential and the thermodynamic potential decrease and then change sign and increase.

• Question 130: When adding K₂SO₄ to the colloid [m(AgI).nI-.(n-x)K+]x-.xK+, which ion causes coagulation.

• Answer: K+

• Question 131: When As₂S₃ colloid with positive charge comes into contact with KCl, KNO₃, KI, KBr, KF electrolyte solutions, which solution does the As₂S₃ colloid adsorb BEST?

• Answer: KI

• Question 132: Knowing that AgI colloid has a negative charge and comes into contact with a mixture of electrolytes KCl, FrCl, LiCl, CsCl, RbCl, which solution does the AgI colloid adsorb BEST?

• Answer: CsCl

• Question 133: What is the most important factor affecting coagulation?

• Answer: Electrolyte

• Question 134: When the concentration of the electrolyte increases during coagulation, what happens?

• Answer: The zeta potential decreases, the electrostatic repulsion force decreases.

• Question 135: When treating river water with aluminum sulfate, after a period of time, the colloidal particles precipitate. What is this phenomenon called?

• Answer: Mutual coagulation.

• Question 136: To stabilize a colloidal system, the electrostatic repulsion force must be increased. This means that:

• Answer: The surface of the colloidal particles must be charged with adsorbed ions to increase the thermodynamic potential and the zeta potential of the system.

• Question 137: When increasing the concentration of a semi-colloidal system, the equilibrium shifts to favor the formation of what?

• Answer: Gel

• Question 138: Which of the following dispersions is not a coarse dispersion?

• Answer: S/S dispersion.

• Question 139: Choose the incorrect statement about emulsions.

• Answer: It is a R/L dispersion.

• Question 140: Which of the following uses of coarse dispersions is correct in Pharmacy?

• Answer: Aerosols are used as drugs with rapid action.

• Question 141: What is the role of an emulsifier?

• Answer: It concentrates on the surface of the dispersed phase, reduces surface tension, and charges the surface.

• Question 142: What factor does emulsion inversion mainly depend on?

• Answer: Emulsifier.

• Question 143: What is usually added to protect suspensions used as drugs in Pharmacy?

• Answer: High molecular weight compounds, surfactants.

• Question 144: To reduce creaming in emulsions, what is needed?

• Answer: Reduce the density difference between the two phases.

• Question 145: What is the structure of a soap micelle?

• Answer: The non-polar head points inward, the polar head points outward to form a spherical or planar micelle.

• Question 146: When preparing an O/W emulsion to ensure stability, what is usually added?

• Answer: Add sodium stearate.

Note: This is a summary, not a verbatim translation. Please refer to specialized literature for a better understanding of each topic.