Differences in Solubility Conditions of Solubility Miscible vs. Immiscible Colligative Properties
Why are there differences in solubility? • General Rule = Like Dissolves Like • What makes substances similar or alike? • CASE #1: Types of bonds • CASE #2: Polarity • CASE #3: Type of intermolecular force
CASE #1 : TYPES OF BONDING • EX. Salt (NaCl) + water (H2O) • Ionic compounds dissolve in aqueous solutions via a process called hydration.
CASE #2: POLARITY • EX. Water + Animal Fat • Salt (NaCl) + Vegetable Oil • LiCl + C6H5CH3 (Toluene)
CASE #3: TYPE OF IMF • MISCIBLE = dissolve in each other at all proportions, have similar IMFs • solvent considered to be substance present in larger amount • EX. alcohol + water • IMMISCIBLE = substances do NOT dissolve in each other at all proportions, do not have similar IMFs • EX. water + oil Italian Salad Dressing
What are colligative properties? • Properties that depend on number of solute particles in a solution or concentration
VAPOR PRESSURE DECREASES • If you increase the concentration, the vapor pressure is the pressure above the liquid in a closed container • As # of solute particles increases, they attract molecules of solvent and hold solvent particles in solution (Prevent Escape!)
BOILING POINT INCREASES • Boiling Point is the Temperature where atm pressure = vapor pressure. • As # of solute particles increase, vapor pressure decreases thus it will take more energy to raise the vapor pressure back to equilibrium with atm pressure.
FREEZING POINT DECREASES • Adding solute to solvent lowers the normal freezing point. • Solute interferes with formation of solid crystals. • In order to freeze molecules must be attracted to each other (clump/cluster together) and if solute molecules are in the path, solvent particles can’t clump.
Why do we apply salt to roadways/walkways in the winter? • LOWERS FREEZING POINT! We use salt solutions involving NaCl and CaCl.
Why do we apply salt to roadways/walkways in the winter? • LOWERS FREEZING POINT!