Chapter 2 Flashcards
attraction like molecules
cohesion
attraction of unlike molecules
adhesion
reaction between two molecules that forces them apart.
repulsion
direction of decrease in attraction
moving away from one another
direction of increase in attraction
moving toward one another
to cohere
attractive forces
to prevent from interpenetrating and annihilating each other
repulsive forces
is due to the interpenetration of the electronic clouds of molecules and increases exponentially with a decrease in distance between molecules
repulsion
Measure of the strength of the bonds
bond energies
Hydrogen bonds
2-8kcal/mole
Covalent
50-100 kcal/mole
Ionic
over 100 kcal/mole
solid to liquid
melting
solid to gas
sublimation
reverse of sublimation; condensation into the solid state
deposition
4th phase; in between crystalline and liquid states; “liquid crystalline state”
mesophase
exists under high pressure and temperature and has properties intermediate between those of liquids and gases.
supercritical fluid
the pressure, temperature, and volume of gas are related to each other
Ideal Gas Law
The volume and pressure of a given mass of gas at constant temperature
Boyle’s law
the volume and absolute temperature of a given mass of gas at constants pressure are directly proportional
Gay-Lussac’s- Charles
The approximate molecular weight of a gas can be determined by use of what law
ideal gas law
most common way to determine the molecular weight of easily vaporized liquids such as alcohol and chloroform.
Regnault and Victor Meyer Methods
The theory that was developed to explain the behavior of gases and to lend additional support to the validity of the gas laws
Kinetic molecular theory
composed of molecules of a finite volume that tend to attract one another.
real gases
accounts for the internal pressure per mole resulting from the intermolecular forces of attraction between the molecules
a/V2
accounts for the incompressibility of the molecules, that is the excluded volume
b
have high internal pressures and serve as solvents only for substances of similar internal pressures
polar liquids
have low internal pressures and are not able to overcome the powerful cohesive forces of the polar solvent molecules
non-polar solvents
if the temperature is elevated sufficiently, a value is reached above which it is impossible to liquefy a gas irrespective of the pressure applied; the temperature above which a liquid can no longer exist
critical temperature
liquids are denser than gases and occupy a definite volume
True
an ideal gas is allowed to expand so rapidly that no heat enters the system
adiabatic expansion
an ideal gas is allowed to expand so rapidly that no heat enters the system
Joule-Thomson Effect
when the rate of condensation equals the rate if vaporization at a definite temperature, the vapor becomes saturated
equilibrium
the pressure of the saturated vapor pressure above the liquid
Equilibrium vapor pressure
occurs by the precipitation of the compound out of solution and into an ordered array
crystallization
show definite melting point, passing sharply from solid to liquid state
crystalline solids
6 distinct crystal systems (symmetry)
▪ Cubic- sodium chloride ▪ Tetragonal- urea ▪ Hexagonal- iodoform Rhombic- iodine ▪ Monoclinic- sucrose ▪ Triclinic- boric acid
the morphology of a crystalline form
habit
crystallize with their chains lying in a parallel arrangement
Aliphatic hydrocarbons
crystallize in layers of dimers with the chains lying parallel or tilted at an angle with respect to the base plane
fatty acids
hard and brittle; high melting points
Ionic and atomic crystals
soft; low melting points
molecular crystals
elemental substances like carbon and sulfur existing in more than one crystalline form
allotropic
residual solvents can be trapped in the crystalline lattice
solvates
supercooled liquids in which the molecules are arranged in a somewhat random manner as in the liquid state
amorphous solids
the temperature at which a liquid passes into the solid state
freezing points
a system at equilibrium readjusts so as to reduce the effect of an external stress.
chatelier’s principle
molecules are mobile in two directions and can rotate about one axis
SMECTIC
Smectic
SOAPLIKE OR GREASELIKE
the molecules rotate only about one axis but are mobile in three dimensions
Surfactants nematic
threadlike
Surfactants nematic
have flow properties of liquids
mobile
behaves as a gas irrespective of the applied P
Critical T
is the minimum P required to liquefy a gas at a given temperature
Critical P
on a DSC arises from desolvations, melting, glass transitions and decompositions.
endothermic reaction
measured by DSC is usually indicative of a decomposition
exothermic reaction
determines whether the desolvation may be attributed to water or residual solvents from chemical processing
Karl Fischer
the ability of a solid to continuously absorb water until it goes into solution
Delinquescence
weight loss measured under low relative humidity controlled with different salts
desorption
formulated by J. Willard Gibbs
Phase Rule
determines the least number of intensive variables that can be changed without changing the equilibrium state of the system
Phase Rule
as a homogeneous physically distinct portion of a system that is separated from other portions of the system bounding surfaces
Phase
- is the smallest number of constituents by which the composition of each phase in the system at equilibrium can be expressed in the form of a chemical formula or equation
Number of components
Systems in which the vapor phase is ignored and only solid and/or liquid phases are considered
Condensed system
the composition of two or more compounds that exhibits a melting temperature lower than that of any other mixtures of the compounds
Eutectic mixture/composition
is the component ratio that exhibits the lowest observed melting point -provides information on solutes interacting in solution
Eutectic point
the solid phase is an intimate mixture of fine crystals of 2 compounds -results to lowest temperature over a composition range
Contact melting
are examples of solid dispersions
Eutectic systems
each solid phase contains both components, that is, a solid solute is dissolved in a solid solvent to give a mixed crystal
Solid solutions
each solid phase contains both components, that is, a solid solute is dissolved in a solid solvent to give a mixed crystal
Solid solutions
molecular dispersion of one component in another where the overall solid is amorphous
Amorphous or glass solutions
pointed to the analogy between human behaviour and molecular phenomena
Moelwyn-Hughes
refers to the different arrangement of atoms resulting from rotations about single bonds
Conformation
are weak forces that involve the dispersion of charge across a molecule called a dipole
Vander Waals forces
dipole-dipole (orientation effect)
Keesom forces
dipole-induced dipole (conduction effect)
Debye force
induced- dipole induced-dipole (dispersion effect)
London force
positive pole
cationic
negative pole
anionic
Three primary states of matter
o Gases
o Liquids
o Crystalline solids
also recorded in atmosphere or in millilitres of mercury because of the use of barometer in pressure movement
Pressure
mass per unit volume
density
showed that a lighter gas diffuses more rapidly through a porous membrane than does the heavier one
graham
special case of polymorphism
allotropic
is a polymorphous natural fat
Theobroma oil, or cacao butter
pointed out the relationship between polymorphism and the preparation of cacao butter suppositories
Riegelman
can also be a factor in suspension technology.
Polymorphism
Factors that affect the interconversion of the different cortisone acetate forms
- Heating
- Grinding under the water
- Suspension in water
studied the crystalline forms of tamoxifen citrate, an antiestrogenic and antineoplastic drug used in the treatment of breast cancer and postmenopausal symptoms
Goldberg and Becker
are sometimes called pseudopolymorphs
Solvates
change from one form to another is reversible
Enantiotrophic
transition takes place in one direction only
Monotropic
glass, pitch and many synthetic plastics
Amorphous Solids
- first recorded observation of a thermotropic liquid crystal in 1888 when he heated cholesteryl benzoate.
Reinitzer
is the most commonly used method and is generally a more useful technique
Differential scanning calorimetry
the least number of intensive variables that must be fixed/known to describe the system completely
Number of degrees of freedom
shows the limit of temperature and concentration within which two liquid phases exist in equilibrium
Curve gbhci
is the point at which the liquid and solid phases have the same composition
Eutectic point
