Mixtures And Solutions Flashcards
Molar conc
C = n/v
Molality
B = n/mass, treats solute and solution separately
Does molarity change with temp
Yes as volume changes with temp
Does molality change with temp
No as mass is constant
Why are volumes not additive
Interaction of molecules in mixture may be different than in pure substance
Implication of Gibbs Duhem equation
Chemical potential of one component of a mixture can’t change independently of chemical potentials of other components
Raoult’s law
Pa = xa x p*a
Dalton’s law
Ptot = Pa + Pb = xa x Pa + xb x Pb
Why does ΔmixH = 0
Molecules in solution have to interact, intermolecular forces required to prevent evaporation, two liquids mix and form ideal solution so no change in interaction
Positive derivation from Raoult’s law
A-B less attractive than A-A and B-B, Pvap > Pideal
Ideal-dilute solutions
Mole fraction of A 0.98<A<1, solvent molecules of a almost exclusively neighboured by other A molecules so behaves like pure A
Henry’s law
0<xb<0.02, B almost exclusively interacts with A so focus on A-B interaction
What does activity coefficient γ vary with
P, T and xa
Colligative properties
Depend on ration of number of solute parties to number of solvent particles
Examples of colligative properties
Bpt elevation, Fpt depression and osmosis
