Properties of Solutions

Electrolytes Solutions have different properties than the pure solvents When ionic compounds dissolve in water, the solution has the ability to conduct electricity. Solutions that conduct electricity are called electrolytes. Certain classes of covalent molecules will also conduct electricity: acids and bases

Electrolyte or Non-electrolyte? CH3OH (l) + H2O  CH3OH(aq) NaOH(s) + H2O  NaOH(aq) NaOH(s) + H2O  Na+(aq)+ OH- (aq) CH3OH (l) + H2O  CH3OH(aq) no ions!!

The water solution of which of the following substances is the best conductor of electricity? KCl C6H12O6 CO2 CO

Freezing Point Depression When a solute is added to a solvent, there are attractive forces between solute and solvent These attractive forces make it harder for solute molecules to line up in a crystal lattice, lowering the freezing point of the substance. The lowering of the freezing point is proportional to the number of solute particles, and the nature of the solvent.

Boiling Point Elevation The presence of solute particles raises the boiling point. It takes more energy to vaporize solution because the solute-solvent attractions have to be overcome.

Freezing Point Depression Boiling Point Elevation For both of these phenomena, the magnitude of the drop in FP / rise in BP depends on the solvent only. The nature of the solute is not important! Ions, atoms, or molecules – it doesn’t matter. Only the number of particles is important.

What occurs when NaCl(s) is added to water? The boiling point of the solution increases, and the freezing point of the solution decreases. The boiling point of the solution increases, and the freezing point of the solution increases. The boiling point of the solution decreases, and the freezing point of the solution decreases. The boiling point of the solution decreases, and the freezing point of the solution increases.

Which would lower the freezing point of 1 L of water the most? 1 mole of C6H12O6 1 mole of NaCl 1 mole of CaCl2 C6H12O6 (s) + water  C6H12O6 (aq) 1 mole particles NaCl(s) + water  Na+(aq) + Cl-(aq) 2 moles CaCl2(s) + water  Na+(aq) + 2Cl-(aq) 3 moles

Which solution containing 1 mole of solute dissolved in 1000 grams of water has the lowest freezing point? KOH(aq) C2H12O6(aq) C2H5OH(aq) C12H22O11(aq)

Which concentration of a solution of CH3OH in water has the lowest freezing point? 0.1 M 0.01 M 0.001 M 0.0001 M