Chapter 13 - Solutions Flashcards
Ion-dipole
Must be strong enough to compete with ionic and hydrogen/d-d/LDF forces
Solution
Homogenous mixtures of two or more pure substances
How does a solution form
Solvent pulls solute particles apart and surrounds them
Three processes that affect energetics of solution
Separation of solute particles
Separation of solvent particles
New interactions between solvent and solute
Heat is absorbed in dissolution of NH4NO3 in water because
Increasing entropy leafs to lower energy of system
Saturated solution
Solvent holds as much solvent as possible. Dissolves solute is in dynamic equilibrium with solid solute particles
Unsaturated solution
Less solute than can dissolve in the solvent is dissolved
Supersaturated solution
Solvent holds more solute than normally possible (unstable)
Factors that affect solubility
Polar dissolves polar
Forces soluble by like forces
Gases in solution
Solubility of gas in water increases with mass
Larger molecules have stronger dispersion forces
Solubility of gas in liquid is directly proportional to its pressure
Henry’s law
Sg=kPa
Temperature
Solubility of solid solutes in liquid solvent increase with temperature.
Opposite for gas
Five ways of expressing concentration
Mass percentage Parts per million Mole fraction Molarity Molality
Colligative properties
Changes depend only on number of solute particles present
Ex: vapor pressure, boiling pt elevation, freezing pt depression, and osmotic pressure
Vapor pressure
Vapor pressure of a solution is lower than that of pure solvent b/c of solute solvent intermolecular attraction
Boiling pt and freezing pt
Nonvolatile solute solvent interactions also cause solutions to have higher boiling pts and lower freezing pts than the pure solvent
Colligative properties of electrolytes
Depen on number of particles dissolved
Show greater changes than those of non electrolytes
Osmosis
Semipermeable membranes
Hypertonic
Concentration outside cell is greater
Flow of water out of the cell
Crenation results
Hypotonic
Concentration outside cell is less
Water flows into cell
Hemolysis results
Isotonic
Same concentration on both sides of membrane
Colloids
Suspension of particles larger than individual ions or molecules but too small to be settles by gravity
Tyndall effect
Colloid suspensions can scatter light
Ex: milk can look blue
Colloids in biological system
Polar/hydrophilic end
Non polar/hydrophobic end
Protein folding if bad can result in cystic fibrosis
Can aid in emulsification of fats and oils in aqueous solutions
If Ionic salt is soluble in water
It’s because the ion-dipole interactions are strong enough to overcome the lattice energy of salt crystal
Why do endothermic processes occur
Enthalpy may increase but the total energy of the system can still decrease if the system becomes more disordered
Glucose
Very soluble in water
Cyclohexane
Not soluble in water
Dispersion forces
Vitamin A
Soluble in non polar compounds (like fats)
Vitamin C
Soluble in water
Vant hoff factor
Delta T = Kf * m * i
