Chapter 9- Solutions Flashcards
When new interactions are stronger than the original ones in the solution
Exothermic and its favored at low temperatures
When the new interactions are weaker than the original ones in a solution
Endothermic. Favored at high temperatures
Ideal solutions
Strength of original and new solution is same. Change in enthalpy is close to zero (dissolution = 0)
What does 🔺G say about solubility?
+ means nonspontaneous and insoluble
- means spontaneous and soluble
Molar solubility middle mark
0.1M and above - soluble
Under 0.1M- sparingly soluble
2 must know solubility rules
- All salts containing ammonium (NH4+) and alkali metals (group 1) cations are water soluble.
- All salts containing nitrate (NO3-) and acetate (CH3COO-) anions are water soluble.
Chemically reacting species in a molecule?
Cation
Molarity
moles of solute / liters of solution
Molality
moles of solute / kilograms of solvent
Normality
Reaction dependent. If in a solution something will accept 5 electrons then it’s 5N.
Dilution equation
MiVi = MfVf
M- Molarity
V- volume
When is the change in free energy zero?
Equilibrium
Ksp
Solubility product constant/ equilibrium constant. No liquids or solids included.
Ion product
Used to determine whether the solution has reached saturation (same equation as Ksp)
Relationship b/w IP and Ksp
IP > Ksp -supersaturated/precipitation will occur
Molar solubility
Maximum number of moles that can be solvated before the solution becomes saturated
Sparingly soluble salt of general formula MX or MX2 or MX3 will have what Ksp (respectively). Assuming no common ion effect. X = molar solubility.
MX: Ksp = x^2
MX2: Ksp = 4x^3
MX3: Ksp = 27x^4
Common ion effect
Reduction in molar solubility when the solvent already has one of the solutes constituent ions.
Colligative properties
Physical properties of solutions that are dependent on concentration of dissolved particles but not the chemical identity. (Ex: vapor pressure depression, boiling point elevation, etc.)
Raoults law for vapor pressure depression.
As solute is added to solvent the vapor pressure of solvent decreases. Mainly if the two are similar reactants.
Pa = XaPa*
Pa-vapor pressure of solvent A
Xa-mole fraction of solvent A in solution
Pa*-vapor pressure of solvent A in pure state
Boiling point
Temperature where the vapor pressure of the liquid equals the ambient (incident) pressure
What happens to the boiling point of a solution when you add a solute?
Boiling point increases
Boiling point elevation formula
Increase in bp = iKbm
i- vant hold factor(number of particles the compound dissociates into)
Kb- proportionality constant (given)
m- Molality of solution
Freezing point depression equation
🔺Tf = iKfm
i- vant Hoff factor
Kf- proportionality constant (given)
m- Molality
Do pure solutions or mixed have lower freezing point?
Mixed solutions have lower freezing points. Harder to get lattice structure with mixtures
Boiling point of water
373K
Freezing point of water
273K
Relationship between solubility of gases in liquids and atmospheric pressure
Directly proportional
