CHEM 120 Lecture Notes - Lecture 17: Freezing-Point Depression, Colligative Properties, Magnesium Bromide
1
Solutions & Colloids: P2
A solution always freezes at a lower T than the pure solvent
Ideal Solubility; freezing point depression
2 ASSUMPTIONS:
- Solute is non-volatile
- The solid that freezes fro solutio is super solet solute o’t icorporate ito the lattice
structure, only the solvent freezes)
Osmosis: spontaneous because entropy gains during mixing (check units, should end up atm)
- colligative property, no need for chemical identity, only needs the concentration of solute vs.
solvent
- Solvent flows from a more dilute solution to a more concentrated one (more water moves to
less water)
- Osmotic Pressure: pressure that must be applied to prevent the net flow of solvent
- R is the gas constant L atm per K
- T of human blood is 36.7
Osmotic Pressure and Cells:
- Iso: a red blood cell in an isotonic solution the rate of flow out = in
- Hypotonic solution has a lower concentration of particles than the cell, cell absorbs water and
swells until it bursts
- Hypertonic solution has a higher concentration of dissolved particles than the cell, water moves
out of the cell causing it to shrink
Strong Electrolytes:
- Dissociates completely to form ions, each mole of solute give MORE than 1 mol of dissolved
particles
- E.g. NaCl → Na+ +Cl-
- K2SO4 → 2K+ + SO42-
- MgBr2 → Mg2+ + 2Br-
The Va’t Hoff factor i is hat e ould expect, SLIDE
- Ions are hydrated, remain clustered together in solution forming an atmosphere, this effect is
greater for a more concentrated solution
- Greater the cocetratio of the solutio, greater the deiatio fro the Va’t Hoff factor
find more resources at oneclass.com
find more resources at oneclass.com
cudapuca and 38677 others unlocked
26
CHEM 120 Full Course Notes
Verified Note
26 documents