Self Assessments for Physical Pharm Exam 1

With reference to states of matter, identify the correct statement from below

Gases have the most kinetic energy

Quartz and glass are examples for (please refer to the relevant slide as needed:

crystalline and amorphous forms of silicon dioxide, respectively

Often, amorphous form of a drug material are preferred for formulations over crystalline material. the rationale for this is as follows:  

greater solubility of the amorphous drug in water

Identify the correct statement from below regarding a crystalline form of a drug:

has a greater molecular order than an amorphous form 

Propane and acetaldehyde (see structures) have the same molecular weight; 44 atomic mass units (AMU).  For this reason, you may expect them to have similar physical properties. Yet, propane is a gas while acetaldehyde is a liquid at room temperature. Using intermolecular forces that you learned in class, explain why this may be the case. Make sure you use the following terms in your answer: electronegativity, polarity (or dipole moment) and intermolecular attraction forces. 

Propane does not have a strong dipole so there are no strong IMF forces which is why it is a gas at room temp compared to acetaldehyde which has significant dipole-dipole interactions and IMF forces, which is why it is a liquid.

According to Gas Laws, which of the following statements is accurate?

As pressure increases, volume decreases

Pressure applied by a gas may be defined as force per unit area.

True

When you open a can of seltzer (water+CO2), you can see the gas previously dissolved in the water, bubble out. This is best explained by:

Henry’s Law

Applying pressure can liquefy a gas provided it is done..

below its critical temperature

For the gas equation PV = nRT, T represents the temperature in degrees Celsius.   

False

A liquid has strong intermolecular attraction forces. Which of the following may be true regarding this liquid? Select all that apply.

Has low vapor pressure

Will freeze easily upon cooling

High surface tension

High viscosity

When activated, this gas  delivers the drug from an  inhaler and is called a

Propellant

Which of the following represents an increasing order of bond energies?

Permanent dipole/induced dipole, H bonding, ionic bonding

Regarding the retinovir polymorphs, which of the following statements are accurate?

While present as single molecules, both are equally effective against HIV

Which of the following statements is/are true with reference to polyethylene glycol?

PEG 400 has a smaller average molecular weight than PEG 600

In the Ritonovir example that was discussed in class, we talked about two crystalline polymorphs of the drug, Form 1 and Form 2 (see below). Form 1 was more soluble but thermodynamically less stable and upon storage, converted to the less soluble but more stable Form 2. If you were asked to guess which of these two forms has a higher melting point, what would you guess? What is the rationale for your answer?   

Form 2 is thermodynamically more stable than Form 1 meaning that it has stronger IMF bonds and requires more energy or heat to disrupt their bonds

The chemical structural formula of a particular form of amoxicillin is shown below.  Based on this information, which of the following labels may be most appropriate for this drug?

A hydrate

The principal reason due to which molecules exhibit polarity is:

Electronegativity

Which of the following forces stabilize a cell membrane's lipid structure?

None of the above, lipid tails stabilize each other through dipole-induced dipole interactions

The Gatton College of Pharmacy sits 1600 ft above sea level.  What physical property of water is this fact likely to affect most noticeably? 

boils before temp reaches 100 deg C

Red blood cells placed in a 0.45% w/v saline solution will shrivel up; a phenomenon called crenation.  

False

Calculate the molarity of 0.9% w/v NaCl solution (Mol wt of NaCl = 58.5). Then calculate the osmolarity of the same solution.  

Molarity: 0.154 moles/L

Osmolarity: 308 milliosmoles/L

Vapor pressure is affected by which of the following characteristics of a solute?

# of particles

What is the typical osmolarity of human plasma?

290 mosmol/L or 0.29 osmol/L

A hypotonic solution may be used to relieve cerebral edema as it can draw the fluid from the tissue back into the blood vessels.  

False

According to Raoult's law, vapor pressure (VP) of solution  = VP of pure solvent * mole fraction of solute

False

A patient suffered an acute head injury and was admitted to the hospital. Upon investigation, high intracranial pressure was suspected and the patient received an infusion of hypertonic mannitol (10%w/v) solution (~596 mOsmol/Ll). What is the rationale behind this treatment?  

Traumatic injury to the brain may result in local fluid accumulation (edema) and a resultant increase in intracranial pressure (ICP). Since the problem is extracellular fluid accumulation that is exerting pressure on the brain tissue, hypertonic solution infusion is indicated. A solution like 10% mannitol will exert osmotic pressure inside the blood vessel and draws in fluids from the outside tissues like the brain. This will relieve the edema.  

The osmolarity of a 10% mannitol solution is 596 mOsmol/L. What is the osmolarity of a 15% mannitol solution? Please explain your answer below.    

Osmolarity: 894 mOsmoles/L

What is the vapor pressure of water at its boiling point in Denver Colorado? Note that Denver, Colarado is around 5000 ft above sea level.  

Less than 760 mm Hg

When some solutes (e.g. starch) are added to water, the viscosity of the resultant solution is found to be greater than that of the original solvent. However, 'raising of viscosity' is not a colligative property. Why is this?

Viscosity depends on the nature of the pure solute

Van't Hoff equation for osmotic pressure calculation is as follows: π = imRT. Based on this equation, which of the following statements is FALSE? (Note: If a solute is ionizable, assume it is 100% ionized)

1 M NaCl exerts more osmotic pressure than 1M MgCl2

Adding common salt would depress the freezing point of water. However, if you added glucose instead of salt, it would not have an effect on the freezing point as glucose does not ionize.  

False

In the Van't Hoff equation for osmotic pressure (π = imRT), the value of i changes with the degree of ionization. Weak electrolytes will have a smaller i than strong electrolytes.  

True

The osmolarity of a 1M sodium citrate solution is what? Note that each molecule of sodium citrate has 3 sodium ions and one citrate ion. Assume 100% ionization.  

4M

The reason a cell membrane is considered as a semi-permeable membrane is:

Water but not  proteins and large ions pass

Osmosis is defined as the solvent migrating through a semipermeable membrane from region of higher concentration to a region of lower concentration.  

False

Assuming complete ionization, what would be the vant Hoff factor (i) for a solution of 1 M barium hydroxide (Ba(OH)2)?

3

Which of the following properties is not considered a physical characteristic of a pure liquid like water?

osmotic pressure

Van't Hoff equation for boiling point elevation (∆Tbp=i∗Kbp∗m) is used to determine how a solution might have a higher boiling point than a pure solvent. The term m here indicates:  

moles of solute/1 kg of solvent

At 75 ^oC, the vapor pressure of pure water is 39 kPa. Which one of the following is the most likely vapor pressure for a 1.5 M solution of sucrose (aqueous) at the same temperature? Note: kPa stands for kilo pascal, SI unit for pressure.  

37 kPa

With regards to tissue perfusion at the arteriole-venule junction, which of the following statements is true?

Osmotic pressure draws water into the blood vessel