HOMOGENOUS SYSTEM Flashcards
consist of at least two phases ÿith one or more internal/disperse phases contained in a single continuous/external phase
Dispersion
suspended particles are completely dissolþed; not large enough to scatter light but are small enough to be disperses = homogenous
True Solution
mixture of two or more components that form a homogenous molecular dispersion/one-phase sāstem.
True Solution
scattering of light
Tyndall effect
solution composed of only two substances: solute & solvent
Binary Solution
independent of the amount of the substances in the system
Intensive Properties
dependent on the quantity of the matter in the system
Extensive Properties
depend on the total contribution of the atoms in the molecule or on the sum of the properties of the constituents in a solution
* Molecular weight
Additive Properties
depend on the arrangement, and number and kind of atoms within a certain molecule.
* Refraction of light/ refraction
* Electric Properties
* Surface & Interfacial tension
* Solubility of drugs
Constitutive Properties
The triple point of air-free water, at which solid, liquid, and vapor are in equilibrium, lies at a pressure of 4.58 mmHg and a temperature of 0.0098C
delta Tf = Kfm
Depression of Freezing Point
HOMOGENOUS SYSTEM
Dispersion
True Solution
Binary Solution
Additive Properties
Constitutive Properties
Colligative Properties
depend mainly on the number of particles in a solution:
* Vapor pressure lowering
* Boiling point elevation
* Freezing point depression
* Osmotic Pressure
Colligative Properties
Raoult’s Law states that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature:
Psolution = (Xsolvent)(Psolvent)
Lowering of Vapor Pressure
“melting point” of a pure compound; the temperature at which the solid and liquid phases are inequilibrium under a pressure of 1 atm.
Freezing point
temperature at which vapor pressure of the liquid becomes equal to an external pressure of 1 atm
Boiling point
states that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature:
Psolution = (Xsolvent)(Psolvent)
Raoult’s Law
passage of the solvent into a solution through a semipermeable membrane; tends to equalize the “escaping tendency” of the solution on both sides of the membrane
Osmosis
The BP of a solution of a nonvolatile solute is higher than of the pure solvent as the solute lowers the VP of the solvent.
delta Tb = Kbm
Elevation of Boiling Point
Van’t Hoff Equation for OP
PoV = nRT
WHAT ARE THE TWO MAIN CLASSES OF SOLUTES?
Electrolytes
Non-electrolytes
substances (an acid, a base, or a salt) that in an aqueous solution ionize to “anions & cations.”
have greater freezing point depression and
boiling point elevation than non-electrolytes
of the same concentration.
→ NaCl
Electrolytes
substances that do not ionize when dissolved in water, and therefore do not conduct electricity through the solution.
→ sucrose, glycerin, naphthalene, and
urea
Non-electrolytes
“M” , “L”
–> Moles of solute in 1L of solution
Molarity
“N”
–> Gram equiþalent weights of solute in 1L of solution
Normality
“m”
–> Moles of solute in 1000 g of solþent
Molality
“N”, “x”
–> Ration of the moles of one constituent
(solute) of a solution to the total moles of all constituents (solute & solvent)
Mole fraction
mg of solute in 100 ml of solution
Milligram percent
“w/v”
–> g of solute in 100 mL of solution.
Percent weight-in-volume
–> grams of solute in 100 g of solution.
“w/w”
Percent by weight
–> mL of solute in 100 mL of solution
“v/v”
Percent by volume
→No change in the ppts. of the components when they are mixed to form solution
Ideal Solutions
Moles of one constituent in 100 moles of the solution; obtained by multiplying mole fraction by 100
Mole percent
The partial vapor pressure of each volatile constituent = vapor pressure of the pure constituent x its mole fraction in the solution
Ideal Solutions
Psolution = (Xsolvent)(Psolvent)
Lowering of Vapor Pressure
No heat is evolved/ absorbed during the mixing process
Ideal Solutions
PA= (VpA)(X)
Ideal Solutions
No shrinkage/ expansion when the substances
are mixed
Ideal Solutions
delta Tb = Kbm
Elevation of Boiling Point
delta Tf = Kfm
Depression of Freezing Point
→ (in gas) complete absence of attractive forces; (in solution) complete uniformity of attractive forces
Ideality
→ does not adhere to Raoult’s law throughout the entire range of composition
Real Solution
law applies to the solvent –
in dilute solutions of real liquid pairs
Raoult’s law
law applies to the solute;
Henry’s law
→When the adhesive attractions between molecules of different species exceed the cohesive attractions between like molecules, the vapor pressure of the solution is less than that expected from Raoult’s ideal solution.
Real Solution
When, under a potential of several volts, a direct current flows through an electrolytic cell, a chemical rxn occurs.
Electrolysis
[addition] of electrons to chemical species. Occurs at the cathode where electrons enter from external circuit, and are added to chemical species.
Reduction
[removal]of electrons from chemical species. Occurs at the anode, where electrons are removed from the chemical species in solution and go into the external circuit.
Oxidation
The fraction of total current carried by the cations/ anions; related to the velocities of the ions, the faster-moving ion = greater fraction of current.
Transference numbers
Current =
Resistance (ohms)
“A, ampere”
Velocities of ions are dependent on:
- Hydration
- Ion size & charge
quantity of electricity in coulombs flowing per unit time.
Current
The passage of 96, 500 coulombs of electricity through a conductivity which produces a chemical change of 1 g equivalent wt. of any substance.
Faraday’s Law
Faraday, F
= 96,486 coulomb/ Eq. wt.
= 23,000 cal/volt Eq. wt.
When electrolytes are dissolved in water, the solute exists in the form of ions in the solution.
ARRHENIUS THEORY
Resistance in Ohms (Ω) of any uniform metallic/ electrolytic conductor
= directly proportional to its length
= inversely prop. to its cross-sectional
area (cm2)
Electrolytic Conductance
NaCl exists as ions in the crāstalline state. Addition of later dissolves the crystals = dissociation of ions
ARRHENIUS THEORY
H2O + HCl –> ?
H3O, Cl-
H2O + NaCl –> ?
Na+, Cl-, H2O
exists as a neutral molecules rather than ion. Addition of water = ionization
HCl
→ NaOH, KOH, Ba(OH)2, Ca(OH)2
Inorganic bases
Inorganic acids → HCl, HNO3, H2SO4, HI
Inorganic bases → NaOH, KOH, Ba(OH)2, Ca(OH)2
Strong electrolytes:
→ HCl, HNO3, H2SO4, HI
Inorganic acids
Acetic acid, Boric acid, Carbonic acid, Ammonium OH, Pb acetate HgCl2, HgI, HgBr
Weak electrolytes
Strong electrolytes are completely ionized in dilute solution and that the derivations of electrolytic solutions from ideal behavior are du to the electrostatic effects of the oppositely charged ions.
DEBYE-HUCKEL THEORY
