12E - Colligative Properties Flashcards
Def: What is a colligative properties?
Properties that depend on the relative amounts of solute and solvent. Independt of chemical idenity of solute.
Recall: What are electrolytes vs N-E?
Seperate into ions when dissolved or does not (can still seperate).
Def: What are extensive and intensive properties?
Depend on quanitiy of matter (moles, mass), like volume, mass…
Independent of quantitty of matter, like desnity, temp.
Def: What is raoult’s law? What does it apply to.
P-solvent = x-solvent*P-pure
P-pure is pressure of pure solvent.
Applies to nonvolatile splutes whose Vap-pressure is negligable and ideal soln.
Def: What is raoult’s law concering pressure of solute?
delta-P = x-solute*P-solventnot
Def: What is a binary liquid?
When mixed are nearly indentical as they have similar moleculat structures.
Def: What is the total pressure vapour pressure formula for two volatile liquids.
Sum of both vapor pressures.
Ptotal = X-AP-A + X-BT-B
A and b are volatile liquids
Theory: When two volatile components are mixed, what happens to each of their vapor pressures?
Both lower, as mole fraction for both goes down.
Theory: what happens to vapour pressure is solute is added to a solution.
Mol fraction goes down, vapour pressue goes down
Def: What is bp elevation? What is the formula?
Increased bp caused by decreased Vapor pressure caused by adding solute.
delta-T-b = Tb - T-bnot = ik_bb
i is van hoff factor, can be ignored for molecular compounds
K-b is bp elevation constant
b is molaity
Theory: What is the bp elevation constant a property of?
Solvent, not solute
Theory: bp of soln is always _ than that of the pure solvent.
greater than
Def: What is the formula for change in boiling point (or bp-elevation) using the original bp?
delta-T-b = k-b * b
Def: What is the vant hoff factor?
Bcs strong electrolytes ionize in soln, i is the apparent number of ions per formula unit.
If non-ionising, it’s 1.
i = number of ions on dissocaition
- Usually lower
Def: What is total molal concentration?
Differnce between freezinf point of pure solvent and freezing point of soln.
Def: What is freezing-point-depression?
Lowering freezing points.
delta-T-f = T-fnot - Tf = ik-fb
Note, this is initial minus final.
Theory: If multiple solutes have equal molalities, how can the lowest freezing point be found?
Look for highest hoff factor.
Def: What is osmosis? what wat will solvent flow?
Movement of solvent particles from higher to lower region of concentration through membrane. Flow away from more dilute soln to a more concentrated one.
Def: What is osmotic pressure?
Pressure that must be applied to prevent net flow of solvent due to osmosis.
cpi = iMRT
Def: What is a strong electrolyte? How can hoff factor determine one?
Disassociated completely into ions. Hoff factor takes into account the dissassoscation of a strong electrolyte to predict effect on soln.
i = measured value for electrolyte soln / expected value
value meaning number of ions produced
Def: What is reverse osmosis?
Pressure applied to diluted side pushes water through membrane.
P > cpi
