Lecture 1 & 2 (Ch. 13): Solutions, IMF, Factors Affecting Solubility Flashcards
are solutions homogeneous or heterogeneous?
- homogeneous
- uniform mixtures
which is present in larger/smaller amounts: the solute or solvent?
- solute: smaller amounts
- solvent: larger amounts
dissolution
-solute breaks apart into ions or molecules
crystallize
- when dissolved solute comes out of solution
- forms a solid
solution equilibrium
-when rates of dissolution and crystallization are equal
saturated solution
- soln is in equilibrium w/ undissolved solute
- contains max amount of solute for a solvent (at specific temp)
- if more solute is added, it won’t dissolve
solubility
-amount of solute needed to form a saturated solution
unsaturated solution
-contains less than max amount of solute (at specific temp)
supersaturated solution
- contains more than the max amount of solute (at specific temp)
- not stable
- if more solute is added, excess solute crystallizes until saturation reached
miscible
-mixes completely
immiscible
- doesn’t mix significantly
- i.e. oil and water
entropy
- increase in disorder (randomness)
- ∆S
why do solutions form?
- due to entropy
- like dissolves in like (polar w/ polar, etc)
intramolecular forces
- forces btwn atoms WITHIN a molecule
- (aka bonds within molecule)
- solid lines
intermolecular forces
- IMF
- btwn atoms of SEPARATE molecules
- dashed lines
london dispersion forces
- movement of electrons within the electron cloud creating instantaneous dipole (temporary partial charge)
- present btwn all molecules
dipole
-distribution of electrons, one end has excess(δ-), the other electron deficient (δ+)
when do london dispersion forces increase?
- with increasing molar mass (more e- to distort)
- the more linear the shape (more contact points)
dipole-dipole
- attraction btwn neutral polar molecules
- permanent dipole
h-bonding
- extra strong dipole-dipole forces
- H atom bonded to FON attracted to lone pari of another FON atom
ion-dipole
- btwn ions and partial charges (dipoles, δ) of polar molecules
- exist when ionic compounds dissolves in polar substance
list the order of strongest to weakest IMF
- ion-dipole
- h-bonding
- dipole-dipole
- london dispersion
how do solutions form?
-forces and bonds are broken and new forces created
solvation
- when solute is surrounded by solvent
- i.e. hydration
hydration
-special case of solvation bc water is the solvent
solute-solute interaction
- must be broken, requires energy
- endothermic (+)
- i.e. ionic bonds
solvent-solvent interaction
- must be broken, requires energy
- endothermic (+)
- i.e. h-bond
solute-solvent interaction
- must be formed, gives off energy
- exothermic (-)
- i.e. ion-dipole
which is favored in solution formation: exothermic or endothermic and why?
- exothermic bc solute-solvent particles are highly attracted to each other
- not endothermic bc entropy is being counteracted by small ∆Hsoln value (if it’s too +, no soln forms)
