Warmup (5min) : Please write the question and try to answer it 1) A combination of 2 or more substances is a: a. homogeneous mixture b. mixture c. solution d. none of the above 2) In soda, CO 2 is the ______ and water is the _________. a.solute; solution b.solvent; solution c.solute; solvent d.solution; solubility 3) Which term describes a solution in which only a small amount of solute is dissolved? a. dilutec. unsaturated b. concentratedd. supersaturated

Types of Matter Matter Compounds Elements Metals Non-Metals Metalloids Heterogeneous Colloid Suspension Mixtures Homogeneous Solutions 2 or more materials that can be physically separated

Ions/molecules are dissolved and scrambled among other molecules (phase: aqueous) Ex. ionic solutions, acids and bases, clean air and … Homogeneous Mixtures SOLUTIONS Visibly different parts in different ‘phases’ (liquid, solid) Ex. milk, blood Heterogeneous Mixture

SOLUTION!!! = Solute : part of solution that is being dissolved solid, liquid, or gas Solvent : the major part of solution; dissolves the solute usually liquid and usually water

Types of Solutions SoluteSolvent Gas Liquid SolidLiquid Solid Oxygen in air CO 2 in soda wine Kool-aid White gold (Au + Ni + Cu + Sn) 1 minute: Identify the phase of the solute and solvent in each mixture

Concentrated solutions contain lots of solute per amount of solution. Dilute solutions contain less solute per amount of solution. Q: Why was the blonde staring at the orange juice carton? A: Because it said ‘CONCENTRATE’

Saturated vs. Unsaturated maximum amount of dissolved solute less than the maximum amount of dissolved solute

Supersaturation When I make Jello, I add boiling water to the mix and then add cold water later. What’s up with THAT? If you heat a solution you can add more solute! Then cool it carefully to create a supersaturated solution. It contains more solute per unit solvent than is typically allowed

Answers to Warmup Questions 1) A combination of 2 or more substances is a: a.homogeneous mixture b.mixture c.solution d.none of the above (a and c are ok but b is best) 2) In a soda, CO 2 is the ______ and water is the _________. a.solute; solution b.solvent; solution c.solute; solvent d.solution; solubility (a: the soda is the solution) 3) Which term describes a solution in which only a small amount of solute is dissolved? a. dilutec. unsaturated b. concentratedd. supersaturated (unsaturated does not necessarily mean dilute)

Which compound has a solubility of 61 g / 100 g H 2 O at 70°C? Answer: NH 4 Cl Solubility (Saturation Point) maximum amount of solute that will dissolve in a solvent under certain conditions the solubility of different ionic solutes is different!

2. What is the maximum solubility of KCl at 50°C in g/L ? 1. Which compound has a solubility of ~41 g / 100. g H 2 O at 50°C? Answer: KCl

x g/L = g solute L solvent 2. What is the maximum solubility of KCl at this temperature in g/L ? x g/L = 41 g L 100. g water = 100. ml water = L water! 410 g/L

3. The concentration of a CaCO 3 solution is g/L. If the total volume is 250 ml, what mass of solute is present? g/L = _x_ L g solute

Molality (m) m = moles of solute kilograms solvent 4. What is the molality of a solution with 332 g of KI in 450. g of water? m = 2.00 moles KI kg Answer: 4.44 molal

Colligative Properties  T b = K b mi  T f = - K f mi Boiling Point Elevation (increased b.p.) Addition of solute lowers the vapor pressure of a liquid. The solvent is too busy keeping the solute dissolved to evaporate! Freezing Point Depression (lowered f.p.) Addition of solute prevents liquid molecules from organizing into the neat orderly pattern required for freezing.

 T b = K b m i  T f = - K f m i  T b = change in bp  T f = change in fp m = molality of the solution (moles/kg) K values depends on the identity of the solvent. K b water = 0.51 ºC∙kg/mole K f water = 1.86 ºC ∙kg/mole i = van ’t hoff factor = number of pieces the solute falls into when it dissolves (more ‘solute pieces’, more  )

5. What is the boiling point of a solution made by adding 2.5 mol aluminum sulfate to 4.5 kg water? ∆T b = K b mi m = mol/kg = 2.5/4.5 = 0.56m i = how many pieces? Al 2 (SO 4 ) 3  2Al SO 4 2- i = 5 *If the solute is ever a molecular compound, like sugar, i = 1 ∆T b = ( 0.51 ºC∙kg/mole) ( 0.56m)(5) ΔT b = ºC…use 2 sf New B.P. = = ºC

6. Consider two solutions, one made by dissolving 1.20 moles of NaCl in 750 g of water and the other with 1.20 moles of CaCl 2 in 750 g of water. Which has the higher boiling point? CaCl 2  1Ca Cl - Δ T b = (0.51 ºC∙kg/mole)(1.6 mole/kg)(3) = ºC so ºC ΔT b = K b m i m = (1.20 moles)/ (0.75 kg) = 1.6 mole/kg NaCl  1Na + + 1Cl - so i = 2 Δ T b = (0.51 ºC∙kg/mole)(1.6 mole/kg)(2) = ºC = ºC CaCl 2

7. Consider two solutions, one made by dissolving 1.20 moles of NaCl in 750 g of water and the other with 1.20 moles of CaCl 2 in 750 g of water. Which has the higher freezing point? Δ T f = - K f m i Δ T f = - (1.86 ºC∙kg/mole)(1.6mole/kg)(2) = ºC (subtract from 0.00 ºC) Δ T f = - (1.86 ºC∙kg/mole)(1.6mole/kg)(3) = ºC NaCl

8. What is the molar mass of a molecular compound if 20.0g are added to 1.50 kg of water and the freezing point is -1.8  C?  T f = -K f mi  T = 0  C  C = -1.8  C -1.8  C = - (1.86)(m)(1) m = 0.97 moles/kg m = mole/kg 0.97 m = (x)/1.50kg x = mol mm = g/mol = 20.0g/ mol = 13.7 g/mol