Solutions Flashcards
Solvation involves…
breaking intermolecular interactions between solute molecules and between solvent molecules and forming new intermolecular interactions between solute and solvent molecules together.
Solute molecules move…
freely in the solvent and interact with it by way of intermolecular forces such as ion-dipole, dipole-dipole, or hydrogen bonding
When interactions between solute and solvent are strong than the original ones…
Solvation is exothermic and the process is favored at low temperatures
When the interactions between solute and solvent are weaker than the original ones…
solvation is endothermic and the process is favored at high temperatures.
Entropy
the degree to which energy is dispersed throughout a system or the amount of energy distributed from the system to the surroundings at a given temperature
When the maximum amount of solute has been added…
the dissolved solute is in equilibrium with its undissolved state, and we say that the solution is saturated.
Both dilute and concentrated solutions are NOT saturated
Solubility Rule 1
All salts containing ammonium and alkali metal (grp 1) cations are water-soluble
Solubility Rule 2
All salts containing nitrate and acetate anions are water-soluble
Chelation
The central cation can be bonded to the same ligand in multiple places.
Used to sequester toxic metals
Percent composition by mass
Mass of solute/ mass of solution x 100%
Mole fraction
moles of A / total moles of all species
* sum of mole fractions in a system will always equal one
Molarity
moles of solute / liters of solution
molality
moles of solute / kg of solvent
Normality
molarity of the stuff of interest in the reaction
Concentration of a solution after dilution can be determined using:
M1V1 = M2V2
M: molarity
V: volume
Ksp
Solubility equilibrium constant for a saturated solution of an ionic compound.
Ksp = [Ag][Cl]
When temperature increases, Ksp increases for non-gas solutes and decreases for gas solutes
Ion product (IP)
Used to determine where a system is in relation to equilibrium position.
IP < Ksp : unsaturated, solute with continue to dissolve
IP = Ksp : saturated, solution is at equilibrium
IP > Ksp : supersaturated, precipitation will occur
Kf (formation constant)
Equilibrium constant for the formation of a complex ion. Typically is larger than Ksp.
Uses products (ions) from dissolution of original solution.
Common ion effect
Reduction in solubility of a substance due to presence of common ions in solution.
Vapor pressure depression
As solute is added to a solvent, the vapor pressure of the solvent decreases proportionately (Raoult’s Law)
- A higher temperature will be required to match the atmospheric pressure, thereby raising the boiling temperature.
PA = XA P°A
PA = VP of solvent A w/ solutes
XA = Mole fraction of solvent A
P°A = VP of pure solvent
Freezing point depression
Presence of more solutes will lower the freezing point of the solution relative to the original solvent.
Osmotic Pressure
Sucking power generated by solutions in which water is drawn into a solution. Water moves in direction of high solute concentration.
The solubility of gases…
is directly proportional to the atmospheric pressure.
