SOLUBILITY Flashcards
concentration of a substance (solute) that dissolves in a given volume of solution (solvent) at a certain temperature to form a homogenous solution
SOLUBILITY
describes the solubility at a specific pH
buffer solubility
buffer solubility is also known as
apparent solubility
refers to the solubility of an ionizable compound in its neutral form
intrinsic solubility
the concentration of solute in a saturated solution at a certain temperature
QUANTITATIVE SOLUBILITY
the spontaneous interaction of two or more substances to form a homogenous molecular dispersion
QUALITATIVE SOLUBILITY
solute in solution is in equilibrium with the solid phase
SATURATED
- solute concentration < saturation point
- the dissolved solute in a concentration is below the necessary for complete saturation
UNSATURATED
- solute concentration > saturation point
- contains more of the dissolved solute than it would normally contain
- undissolved solute is present
SUPERSATURATED
the USP classified solubility into how many groups
7
Refer to standard reference works such as official compendia (e.g., USP, European pharmacopoeia) and the Merck Index for solubilities of specific substances.
United States Pharmacopeia (USP)
Solubility of drugs as parts of solvents required for one part of solute
United States Pharmacopeia (USP)
The greater the ____ between the solute and the solvent (similar physical-chemical properties), the greater the solubility
SIMILARITY
like dissolves like
Polar groups (-OH, -SH, -COOH) relationship w water solubility
increase
Non-polar groups (-CH3) relationship w water solubility
decrease
Ability to form H-bonds is
more significant
Polar solvent dissolve ____ or ____ solutes
ionic or polar
dissolves phenols, alcohols, aldehydes, ketones, and amines
water
Solubility of drug is due in large measure to ____
polarity of the solvent
solubility also depends on ____ features
structural
SOLUBILITY
longer chains
less soluble
SOLUBILITY
straight chain
slightly soluble
increases water solubility
branching
separation of the ends of a dipole and the magnitude of the charges
dipole moment
a quantity measuring the ability of a substance to store electrical energy in an electric field
dielectric constant
ability to store electrical charge
dielectric constant
decreasing polarity (less polar), decreasing water solubility (less water-soluble)
lower dielectric constant
solvents that are unable to reduce the attraction between ions of strong & weak electrolytes because of the solvents’ low dielectric constants
Nonpolar solvents
- can induce a certain polarity in nonpolar solvents
- e.g. ketones & alcohols
- can act as intermediate solvents
semipolar solvents
MISCIBILITY
benzene + alcohol
miscible
MISCIBILITY
polar + nonpolar liquids
miscible
MISCIBILITY
PEG + water + peppermint oil
miscible
REMEMBER
decreasing dielectric constant
decreasing polarity
decreasing solubility
TYSM
what is the solubility of a higher dielectric constant
more soluble
dissolves phenols, alcohols, aldehydes, ketones, amines and other O and N containing compounds
hydrogen bonds
The solute molecules are kept in solution by the weak
van der waals-london
- neither accept nor donate protons
- so cannot break covalent bonds and ionize
- weak electrolytes
aprotic solvents
increases the solubility of ether in water
ACETONE
increases miscibility of the water-castor oil mixture
ALCOHOL
increases miscibility of water and peppermint oil; water and benzyl benzoate
PEG
SOLUBILITY
for substances that exhibit endothermic reaction
INCREASE solubility
SOLUBILITY
for substances that exhibit exothermic reaction
DECREASE solubility
most important drugs are
weak acids or bases
SOLUBILITY
acid + acid
decreased solubility, precipitates
SOLUBILITY
basic + basic
decreased solubility, precipitates
SOLUBILITY
acid + base
ionized, soluble
As a particle becomes smaller, the ____ increases.
surface area
allows greater interaction with the solvent which causes an increase in solubility
larger surface area
When solvation releases more energy than that required to separate particles, the overall process is
exothermic
SOLUBILITY
gases
increased temperature, decreased solubility
Solubility in water is increased by increasing the capacity of the solute for H bonding with ____
POLAR GROUPS
Solubility in water is decreased with an increase in the number of ____ atoms in the solute
CARBON
polymers with a ____ molecular weight are insoluble
HIGH
For many organic molecules, a high melting point means
LOW WATER SOLUBILITY
what isomer is more soluble
cis or trans
CIS
isomer that has a lower melting point
cis or trans
CIS
Increasing ____ increases solubility in polar solvents
UNSATURATION
more soluble than are those that are crystalline (hydrates)
ANHYDROUS SOLUTES
Breaking up the particles of the solute requires
ENERGY
forming new attractive forces between the solute and the solvent ____ energy
RELEASES
heat is absorbed
endothermic
heat is released
exothermic
the separation of particles requires more energy than is released during solvation
endothermic
When solvation releases more energy than that required to separate particles, the overall process is
exothermic
ano ginagawa sa weak acids & bases drugs para maging soluble in water
formulated into salts
SOLUBILITY
acid + base
ionized, hydrophilic, water soluble
a + a
lipophilic, water insoluble
b + b
lipophilic, water insoluble
- When a solution of a weak electrolyte is altered by adding one of its ions (common ion) from another source, the ionization of the weak electrolyte is suppressed.
- An application of Le Chatelier’s Principle
COMMON ION EFFECT
A system at equilibrium will readjust to reduce the effect of external stress
LA CHATELIER’S PRINCIPLE
if a common ion is added, what happens to the solubility
decreases
SOLUBILITY
carboxylic acids
insoluble in water
SOLUBILITY
fatty acids
insoluble in water, soluble in solvents w/ low dielectric constant
SOLUBILITY
hydroxy acids
tartaric & citric
quite soluble in water
SOLUBILITY
potassium & ammonium bitartrates
very soluble in water
used sometimes to dissolve water-insoluble acetylsalicylic aid
sodium citrate
react with dilute alkalies to form water-soluble salts, but they can be precipitated as the free acids if stronger acidic substances are added to the solution
aromatic acids
quite soluble in water because they are solvated through their hydroxyl group
hydoxy acids
tartaric & citric
- form soluble soaps with the alkali metals
- form insoluble soaps with other metal ions
- soluble in solvents having low dielectric constants
fatty acids
SOLUBILITY
Phenol
slightly soluble
- weakly acidic
- slightly soluble in water
- quite soluble in dilute sodium hydroxide
PHENOL
SOLUBILITY
organic compounds containing a basic nitrogen atom
not very soluble in water
- not very soluble in water
- soluble in dilute solutions of acids
organic compounds with N