Forces of Attraction Flashcards
Forces within molecules
Intramolecular Force
Forces between molecules and hold molecules together
Intermolecular forces
Intramolecular Forces
Ionic Bond
Covalent Bonds
Intermolecular Forces
Van der Waals Forces
Ion-Dipole
Ion-induced Dipole
Hydrogen Bonds
Transfer of electrons between metal (electron donor) + non-metal (electron acceptor)
Ionic Bond
Bond Energy of Ionic Bond
> 100 kcal/mol
Energy required remove electron
Ionization Energy
Ability to attract electrons
Electronegativity
Sharing of electrons between non-metal + non-metal
Covalent Bonds
Unequal sharing of electrons; dipole moment
Polar
Equal sharing of electrons
Non-polar
Dipole-Dipole
AKA: Permanent Dipole, Keesom Forces
Bond Energy: 1-7 kcal/mol
Effect: Orientation or Alignment
Example: HCl, Acetone, Phenol, Alcohol
Dipole-Induce Dipole
AKA: Debye Forces
Bond Energy: 1-3 kcal/mol
Effect: Induction
Example: Ethylacetate, Methylene Cl, Ether
Induced-Dipole Induced-Dipole
AKA: London Forces
Bond Energy: 0.5 - 1 kcal/mol
Effect: Dispersion
Example: Carbon disulfide, Carbon tetrachloride, Hexane
Occurs between ionic and polar molecules because ions have strong charge, so partial charge end of the dipole will be attracted to the ion
Ion-Dipole
Occurs between ionic and non-polar molecules
Ion-Induced Ion
Involved in formation of Iodide complex
Ion-Induced Dipole
I2 + NaI or KI (Solubilizing Agent) –> I3 + I2 = Increase solubility
Interaction between a molecule containing Hydrogen atom and strongly electronegative element
Hydrogen Bond
Bond Energy of Hydrogen Bond
2 - 8 kcal/mol
Hydrogen bond accounts for many of the unusual properties of water, including
High dielectric constant (78.4)
High boiling point
Abnormally low vapor pressure (23.8mmHg @ 25C)
Strong Electrolytes completely ionize in dilute solutions & the deviations from ideal behavior are due to electrostatic effects of oppositely charged ions.
Debye-Huckel Theory
Solutions that has lower tonicity as than serum & body fluids; <0.9% NaCl w/v
Hypotonic Solutions
Solutions that has higher tonicity as than serum & body fluids; >0.9% NaCl w/v
Hypertonic Solutions
Solutions that has same tonicity as than serum & body fluids; 0.9% NaCl w/v
Isotonic Solution
Cell effect of Hypotonic Solutions
Swelling/Lysis
Cell effect of Hypertonic Solutions
Shrinking/Crenation
Methods of Adjusting Tonicity
Class I Methods
a. Cryoscopic Method
b. NaCl equivalent method
Class II Methods
a. White Vincent Method
b. Sprowl’s method
Addition of tonicity adjustig agent / NaCl is added to a drug solution, such the final freezing point lowering is that blood or serum
Cryoscopic Method/Freezing Point Depression Method
Strong Electrolytes – 100% dissolution; strong acids/strong bases; ɩ = 2
Weak Electrolytes – incomplete dissociation (80%); weak acids/weak bases
Non Electrolytes – do not dissociate; ɩ = 1
Amount of sodium chloride which has the same osmotic effect as 1 gram of drug
E-value
NaCl Equivalent Method
- Amount of drug * E-value
- 0.9% * volume of solution (mL)
- Step 2 - Step 1
- Step 3 / E-value of tonicity adjuster (if adjusting agent is not NaCl)
E-value formula
E-value = 17 * Liso/MW
Addition of water to make solution isotonic, followed by addition of isotonic or isotonic-buffered solution to make solution to its final volume
White Vincent Method
Formula for White Vincent Method
V = Weight in grams * E-value * 111.1
Simplification of white Vincent method wherein amount of drug is fixed at 1% of a fluidounce solution
Sprowl’s Method
Sprowl’s Method
V = 0.3𝑔 𝑋 𝐸𝑣𝑎𝑙𝑢𝑒 𝑥 111.1
