Solutions Flashcards
homogeneous mixtures composed of two or more substances that combine to form a single phase, usually the liquid phase; consists of a solvent and a solute
solutions
is dissolved in a solvent
solute
the component of the solution that remains the same after mixing
solvent
process of solvent particles surrounding solute particles via electrostatic interactions
solvation/dissolution
process of solvation/dissolution of an aqueous solution (solvent is water)
hydration
the maximum amount of solute that can be dissolved in a given solvent at a given temperature; often expressed as molar ____ (the molarity of the solute at saturation)
solubility
refers to a molecule in which a cation (metallic ions) is bonded to at least one electron pair donor (various neutral compounds and anions, referred to as ligands)
complex ions (coordination compounds)
bonds between a Lewis acid and base that hold complex ions together
coordinate covalent bonds
denotes the amount of solute dissolved in a solvent
concentration
method of expressing concentration:
used for aqueous solutions and solid-in-solid solutions
percent composition by mass
percent composition by mass
(mass of solute / mass of solution) x 100%
method of expressing concentration:
used for calculating vapor pressure depression and partial pressures of gases in a system
mole fraction (𝜒)
mole fraction (𝜒)
𝜒(A) = moles of A / total moles of all species
method of expressing concentration:
the most common unit for concentration and is used for rate laws, the law of mass action, osmotic pressure, pH and pOH, and the Nernst equation
molarity (M)
molarity (M)
M = moles of solute / liters of solution
method of expressing concentration:
used for boiling point elevation and freezing point depression
molality (m)
molality (m)
m = moles of solute / kilograms of solvent
method of expressing concentration:
the molarity of the species of interest and is used for acid-base and oxidation-reduction reactions
normality (N)
normality (N)
N = number of equivalents / liters of solution
dilution equation
M(1) V(1) = M(2) V(2)
defined as equilibrium in the process of creating a solution, where the solute concentration is at its maximum value for the given temperature and pressure
saturation point
the equilibrium constant for a dissociation reaction
solubility product constant (K(sp))
solubility product constant (K(sp))
K(sp) = [A^n+]^m * [B^m-]^n
e.g. K(sp) = [Ag+] [Cl-]
a calculated value that relates where the system is with respect to the equilibrium position (K(sp))
ion product (IP)
ion product (IP)
IP = [A^n+]^m * [B^m-]^n
e.g. IP = [Ag+] [Cl-]
comparison determines the level of saturation and behavior of the solution
comparison of K(sp) and IP
comparison of K(sp) and IP:
indicates the solution is unsaturated, and if more solute is added, it will dissolve
IP < K(sp)
comparison of K(sp) and IP:
indicates the solution is saturated (at equilibrium), and there will be no change in concentrations
IP = K(sp)
comparison of K(sp) and IP:
indicates the solution is supersaturated, and a precipitate will form
IP > K(sp)
the equilibrium constant for complex formation; value is usually much greater than K(sp)
formation/stability constant (K(f))
decreases the solubility of a compound in a solution that already contains one of the ions in the compound; the presence of that ion in solution shifts the dissolution reaction to the left, decreasing its dissociation
common ion effect
physical properties of solutions that depend on the concentration of dissolved particles but not on their chemical identity
colligative properties
accounts for vapor pressure depression caused by solutes in solution
Raoult’s law
Raoult’s law
P(A) = 𝜒(A) P°(A)
where:
P(A) = vapor pressure of solvent A when solutes are present
𝜒(A) = mole fraction of solvent A in the solution
P°(A) = vapor pressure of solvent A in its pure state
decreases the evaporation rate of a solvent without affecting its condensation rate, thus decreasing its vapor pressure
presence of other solutes
shifts in the phase equilibria dependent on the molality (m) of the solution
freezing point depression and boiling point elevation
freezing point depression
ΔT(f) = i K(f) m
where: ΔT(f) = freezing point depression i = van't Hoff factor K(f) = proportionality constant characteristic of particular solvent m = molality of solution
boiling point elevation
ΔT(b) = i K(b) m
where: ΔT(b) = boiling point elevation i = van't Hoff factor K(b) = proportionality constant characteristic of particular solvent m = molality of solution
corresponds to the number of particles into which a compound dissociates in solution
e.g. for NaCl i = 2 (1 for Na and 1 for Cl)
van’t Hoff factor
refers to the “sucking” pressure generated by solutions in which water is drawn into a solution
osmotic pressure (π)
osmotic pressure (π)
π = iMRT
where:
π = osmotic pressure
