Deck 3: Chemical Fundamentals

Question 1

The foundational requirement for partitioning of an analyte is

A) there is a phase boundary
B) two solvents are miscible
C) the system cannot reach equilibrium
D) the analyte is volatile
E) none of the above

Answer 1

A

Question 2

The foundational requirements for extracting an analyte from a matrix are

A) an equilibrium condition and miscible solvents
B) a different in properties and a non-zero vapor pressure
C) an equilibrium condition and an exploitable difference in properties
D) a non-zero vapor pressure and miscible solvents
E) none of the above

Answer 2

an equilibrium condition and an exploitable difference in properties

Question 3

Le Châtelier's Principle describes

A) the relative solubility of solvents
B) a system at equilibrium
C) the solubility of a drug in lipids
D) the solubility of a drug in water
E) none of the above

Answer 3

B

Question 4

A generic chemical process, A + B ↔ C + heat, has reached equilibrium. What happens to the system if we remove the product C?

A) the reaction will be driven to the right to produce more C
B) the reaction will be driven to the left to prevent any more loss of C
C) nothing since the system is at equilibrium
D) the beaker will explode
E) none of the above

Question 5

A generic chemical process, A + B ↔ C + heat, has reached equilibrium. What happens if we add more A?

A) nothing since the system is at equilibrium
B) the reaction will be driven to the left to reduce the heat produced
C) the reaction will be driven to the left to preserve the remaining B
D) the reaction will be driven to the right and produces more C and heat
E) none of the above

Question 6

A generic chemical process, A + B ↔ C + heat, has reached equilibrium. What happens if we add more B?

A) the reaction will be driven to the left to preserve the remaining A
B) the reaction will overheat
C) the reaction will be driven to the left to increase production of C
D) the beaker will explode
E) none of the above

Question 7

For the analysis of blood alcohol, the blood/headspace system must be at equilibrium before analysis. Why?

A) to be sure all the ethanol is in the gas phase
B) to allow the concentrations to stabilize
C) to minimize loss due to leakage
D) to allow the blood components to settle out
E) none of the above

Question 8

The equilibrium constant K is

A) only valid for gas/liquid systems
B) the ratio of the concentration of reactants to heat produced (or absorbed)
C) the ratio of concentrations of products to concentrations of reactants raised to the power of their coefficients
D) is calculated using Le Châtelier's Principle
E) none of the above

Question 9

The K_sp of silver acetate Ag(CH₃COO) is 4.40x10^-3. What is the solubility (S) of this compound

A) 0.0220
B) 0.0663
C) 0.0888
D) 0.135
E) none of the above

Question 10

The K_sp value for barium hydroxide Ba(OH)₂ is 5.00x10^-3. What is the solubility (S) of this compound?

A) 0.108
B) 0.00250
C) 0.150
D) 0.707
E) none of the above

Question 11

Suppose a system described by:
Ba(OH)₂(s) Ba²⁺(aq) + 2OH^-(aq)
Has come to equilibrium. What happens if we add hydroxide ions?

A) All of the remaining solid dissolves
B) The equilibrium is driven to the right
C) The solubility of barium hydroxide increases
D) The solubility of barium hydroxide decreases
E) none of the above

Question 12

has come to equilibrium. What happens if we add H⁺ and to form H₂O?

A) All of the remaining solid dissolves
B) The equilibrium is driven to the right
C) The solubility of barium hydroxide increases
D) The solubility of barium hydroxide decreases
E) none of the above

Question 13

Solubility of a compound such as a drug in fat is called

A) lipophobicity
B) lipophilicity
C) hydrophilicity
D) hydrophobicity
E) none of the above

Question 14

The logP of fentanyl is about 4.1. This means that fentanyl is

A) relatively lipophilic
B) relatively water soluble
C) about equally soluble in water and lipids
D) not very soluble in octanol
E) none of the above

Question 15

The logP of heroin is 1.58. What is the approximate ratio of fat/water solubility of heroin?

A) 2
B) 0.623
C) 0.0263
D) 0.106
E) none of the above

Question 16

The electrostatic attraction between a cation and an anion is an example of a/an

A) intermolecular force
B) intramolecular force
C) covalent bond
D) pi-pi interaction
E) none of the above

Question 17

Gasoline is a complex mixture of relatively non-polar compounds. The primary intermolecular force that allows these compounds to be soluble in one another is

A) hydrogen bonding
B) dipole-dipole
C) ion-dipole
D) induced dipole
E) none of the above

Question 18

What is the primary intermolecular force that binds water molecules together?

A) hydrogen bonding
B) dipole-dipole
C) ion-dipole
D) induced dipole
E) none of the above

Question 19

The [OH-] in a water sample is 4.92x10^-8 M. What is the pH?

A) 2.75
B) 2.8
C) 7.42
D) 9.43
E) none of the above

Question 20

What is the concentration (M) of H⁺ in water at physiological pH (7.4)?

A) 7.4x10^-7
B) 6.6x10^-7
C) 2.5x10^-7
D) 4.0x10^-8
E) none of the above

Question 21

An acidic or basic group on a drug molecule is called

A) a proton
B) an ionizable center
C) the pKa
D) the ionophile
E) none of the above

Question 22

A basic drug has a pKa of 6.3. At what pH will this drug be 50% ionized?

A) 6.3
B) 7.7
C) 8.3
D) 4.3
E) none of the above

Question 23

At what pH will cocaine, a basic drug with a pKa of 8.6, be essentially 100% in the un-ionized B form?

A) 7.4
B) 8.6
C) 10.6
D) 6.6
E) none of the above

Question 24

What form of an acidic drug favors partitioning across a cell membrane (lipid bilayer)?

A) A-
B) HA
C) both are equally favored
D) NaA
E) none of the above

Question 25

What form of a basic drug favors partitioning across a cell membrane (lipid bilayer)?

A) B
B) BH+
C) both are equally favored
D) B•HCl
E) none of the above

Question 26

Which forms of acidic/basic drugs are the most lipophilic?

A) HA/BH+
B) HA/B
C) A+/B-
D) A-/BH+
E) none of the above

Question 27

An analyst receives a sample that contains MDMA, a basic drug with a pKa of 9.9. The analyst dissolves the powder in a buffer solution with a pH of 12. After filtering, they pour the aqueous buffer solution into a separatory funnel. They add chloroform, close and shake. Two layers form. Where will the MDMA be?

A) In the aqueous layer
B) In the chloroform layer
C) equally divided between the two layers
D) it will precipitate out as a solid
E) none of the above

Question 28

The common antibiotic penicillin is taken orally as a sodium or potassium salt. This implies that penicillin is

A) an acidic drug
B) a basic drug
C) a neutral drug
D) a lipophilic drug
E) none of the above

Question 29

An analyst needs to prepare a standard of fentanyl for a toxicological analysis. The standard is supplied as a powder of fentanyl citrate. The formula weight of the citrate salt is 528.6 g/mol and the formula weight of fentanyl alone is 336.5 g/mole. What percentage of the salt is fentanyl?

A) 52
B) 76
C) 64
D) 13
E) none of the above

Question 30

An analyst needs to prepare a standard of fentanyl for a toxicological analysis. The standard is supplied as a powder of fentanyl citrate. The formula weight of the citrate salt is 528.6 g/mol and the formula weight of fentanyl alone is 336.5 g/mole. The analyst is preparing 100.0 mL of the standard at a concentration of 250 ppm (mg/L). How much powder will they have to weigh out to make this standard?

A) 25.0
B) 12.5
C) 50.0
D) 39.3
E) none of the above

Question 31

In the context of drugs, K_sp describes what characteristic?

A) solubility of the drug salt form
B) intrinsic solubility of HA or B
C) solubility as a function of pH
D) solubility at pH = pKa
E) none of the above

Question 32

What controls the intrinsic solubility (S₀) of a drug with an ionizable center?

A) the polarity of B or HA form
B) Ksp of the drug salt
C) pH and pKa
D) K_D
E) none of the above

Question 33

What does LogD describe?

A) The point where the pH of a solution is the same as the pKa
B) The same as logP except the pH of the water is set to 7.4
C) The concentration equilibrium of the acidic and basic forms of a drug
D) the pH at which half the ionizable sites on a drug molecule are charged
E) none of the above

Question 34

A drug molecule that has one acidic ionizable center and one basic ionizable center is called

A) an acibas
B) isoelectric
C) amphoteric
D) just plain weird
E) none of the above

Question 35

An amphoteric drug that is always charged regardless of the pH is what type of compound?

A) just plain weird
B) bielectric
C) isoelectronic
D) zwitterion
E) none of the above

Question 36

An analyst sets up an SPE separation using a solid phase containing C-18 (non-polar). After conditioning and rinsing steps, the elution solvent they use is methanol. This is an example of

A) normal phase (NP)
B) reversed phase (RP)
C) cation exchange (AX)
D) anion exchange (CX)
E) none of the above

Question 37

An analyst sets up an SPE separation using a solid phase containing a polar functional group. After conditioning and rinsing steps, the elution solvent they use is hexane. This is an example of

A) normal phase (NP)
B) reversed phase (RP)
C) cation exchange (AX)
D) anion exchange (CX)
E) none of the above