COLLIGATIVE PROPERTIES the 4 physical effects solutes can have on solutions

COLLIGATIVE PROPERTIES- the physical properties of solutions that are affected by the number of particles and not the identification of dissolved solutes

1. BOILING POINT ELEVATION –Liquids boil when the vapor pressure equals the atmospheric pressure –By adding a solute, the temperature at which the liquid boils is higher. –EX: adding salt to water when cooking makes the water boil at a higher temperature. Cooking noodles will cook faster because the water can reach a higher temperature and your noodles won’t be as soggy!

2. FREEZING POINT DEPRESSION By adding a solute to water, the freezing point is lowered.. EX: salt added to roads makes the water freeze into ice at a lower temperature. EX: antifreeze is added to a car radiator, so the water will not freeze until it reaches a temperature lower than 0

3. VAPOR PRESSURE LOWERING Water pressure exerted in a closed container by liquid particles that have escaped the surface and entered the gaseous state.  by increasing the number of solute particles, the vapor pressure is lowered

4. OSMOTIC PRESSURE Diffusion- the mixing of gases or liquids due to random motions Osmosis – different solvent particles cross a semi-permeable membrane from an area of high solvent concentration to one of lower concentration. Movement of water, not the solute!! Diffusion- the mixing of gases or liquids due to random motions Osmosis – different solvent particles cross a semi-permeable membrane from an area of high solvent concentration to one of lower concentration. Movement of water, not the solute!! A B 1.2 M0.45 M A B A selectively permeable membrane separates two aqueous solutions of potassium chloride (KCl). On the left side of the membrane is solution A composed of 1.24 M solution. On the right side of the membrane is solution B composed of 0.45 M solution. Which side is most concentrated? Which side has the most water? Which way will the water flow? A B A selectively permeable membrane separates two aqueous solutions of potassium chloride (KCl). On the left side of the membrane is solution A composed of 1.24 M solution. On the right side of the membrane is solution B composed of 0.45 M solution. Which side is most concentrated? Which side has the most water? Which way will the water flow?

ELECTROLYTES Ionic compounds are electrolytes This means that they dissociate in water to form a solution that conducts electric current

The 4 colligative properties, once again are… Increase in bp (bp elevation) Decrease in fp (fp depression) Lowering of vapor pressure Osmotic pressure

TRY THESE… MOLARITY What is the molarity of a solution with 50 g sodium carbonate dissolved in 2000 mL of water? M= mol/L 50 g Na 2 CO 3 X 1 mol =.47mol 106 g M=.47 mol =.2M 2L DILUTION How many milliliters of 2.55M NaOH is needed to make a 125 mL of a 0.75M NaOH? M 1 V 1 =M 2 V 2 (2.55M)(V1) = (0.75M)(125mL) V 1 = 36.8 mL