Physical Properties of Solutions Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

용액의 물리적 성질 13.1 용액의 유형 13.2 용해과정의 분자적 고찰 13.3 농도 단위 13.4 용해도에 미치는 온도의 영향 13.5 기체의 용해도에 미치는 압력의 영향 13.6 총괄성

A solution is a homogenous mixture. 균일 혼합물 The solute is(are) the substance(s) present in the smaller amount(s) The solvent is the substance present in the larger amount

A saturated solution contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature. An unsaturated solution contains less solute than the solvent has the capacity to dissolve at a specific temperature. A supersaturated solution contains more solute than is present in a saturated solution at a specific temperature. Sodium acetate crystals rapidly form when a seed crystal is added to a supersaturated solution of sodium acetate.

Three types of interactions in the solution process: solvent-solvent interaction solute-solute interaction solvent-solute interaction  H soln =  H 1 +  H 2 +  H 3

“like dissolves like” Two substances with similar intermolecular forces are likely to be soluble in each other. non-polar molecules are soluble in non-polar solvents CCl 4 in C 6 H 6 polar molecules are soluble in polar solvents C 2 H 5 OH in H 2 O ionic compounds are more soluble in polar solvents NaCl in H 2 O or NH 3 (l)

용액 - 균일 혼합물 조성비 - 농도 물리적 표현법 질량 백분율 화학적 표현법 ( 단위당 화학량 (number)) 몰농도 (M) mol/L solution 몰랄농도 (m) mol/kg solvent 몰분율 (x) mol/mol total

Concentration Units The concentration of a solution is the amount of solute present in a given quantity of solvent or solution. Percent by Mass % by mass = x 100% mass of solute mass of solute + mass of solvent = x 100% mass of solute mass of solution Mole Fraction (X) X A = moles of A sum of moles of all components

Concentration Units Continued M = moles of solute liters of solution Molarity (M) Molality (m) m = moles of solute mass of solvent (kg)

What is the molality of a 5.86 M ethanol (C 2 H 5 OH) solution whose density is g/mL? m =m = moles of solute mass of solvent (kg) M = moles of solute liters of solution Assume 1 L of solution: 5.86 moles ethanol = 270 g ethanol 927 g of solution (1000 mL x g/mL) mass of solvent = mass of solution – mass of solute = 927 g – 270 g = 657 g = kg m =m = moles of solute mass of solvent (kg) = 5.86 moles C 2 H 5 OH kg solvent = 8.92 m

Temperature and Solubility Solid solubility and temperature solubility increases with increasing temperature solubility decreases with increasing temperature

Fractional crystallization is the separation of a mixture of substances into pure components on the basis of their differing solubilities. Suppose you have 90 g KNO 3 contaminated with 10 g NaCl. Fractional crystallization: 1.Dissolve sample in 100 mL of water at 60 0 C 2.Cool solution to 0 0 C 3.All NaCl will stay in solution (s = 34.2g/100g) 4.78 g of PURE KNO 3 will precipitate (s = 12 g/100g). 90 g – 12 g = 78 g

Temperature and Solubility Gas solubility and temperature solubility usually decreases with increasing temperature

Pressure and Solubility of Gases The solubility of a gas in a liquid is proportional to the pressure of the gas over the solution (Henry’s law). c = kP c is the concentration (M) of the dissolved gas P is the pressure of the gas over the solution k is a constant (mol/Latm) that depends only on temperature low P low c high P high c

Chemistry In Action: The Killer Lake Lake Nyos, Cameroon, West Africa Trigger? earthquake landslide strong Winds 1986 Aug. 21 CO 2 Cloud Released 1700 Casualties

Lake Nyos Degassing Schedule Composition (1992) : Layer m : –Water : 105 Mm3 –Gas: 190 Mm3 Layer m : –Water: 17.5 Mm3 –Gas: 80 Mm3 (1992) 5 pipes at 205 m, internal diameter = mm; Liquid flow rate ˜ 2 Mm3/year/pipe Conclusion: after 3 to 5 years, the situation will be safe. Figure © Magma Production

총괄성 Colligative properties are properties that depend only on the number of solute particles in solution and not on the nature of the solute particles. number of solute particles [M A ], m A, X A P B,  mp,  bp, .

Colligative Properties of Nonelectrolyte Solutions Colligative properties are properties that depend only on the number of solute particles in solution and not on the nature of the solute particles. Vapor-Pressure Lowering Raoult’s law If the solution contains only one solute: X 1 = 1 – X 2 P P 1 =  P = X 2 P 1 0 X 2 = mole fraction of the solute P 1 0 = vapor pressure of pure solvent X 1 = mole fraction of the solvent P 1 = X 1 P 1 0

P A = X A P A 0 P B = X B P B 0 P T = P A + P B Ideal Solution P T = X A P A 0 + X B P B 0 = X A P A 0 + (1-X A )P B 0 =P B 0 + X A (P A 0 – P B 0 )

Compisition at Vapor Phase 0

P T is greater than predicted by Raoults’s law P T is less than predicted by Raoults’s law Force A-B Force A-A Force B-B <& Force A-B Force A-A Force B-B >&

Fractional Distillation Apparatus

Boiling-Point Elevation & Freezing-Point Depression  T b = T b – T b 0 T b, T f is the boiling (freezing) point of the pure solvent 0 T b, T f is the boiling(freezing) point of the solution  T b = K b m m is the molality of the solution K b, K f is the molal boiling(freezing) -point elevation(depression) constant ( 0 C/m)  T f = T f – T f 0 0  T f = K f m

Gibbs Free Energy and Temperature for solid, liquid, vapor, solution Gibbs Free Energy solid liquid vapor solution Temperature TfTf TfTf 0 TbTb 0 TbTb

What is the freezing point of a solution containing 478 g of ethylene glycol (antifreeze) in 3202 g of water? The molar mass of ethylene glycol is g. K f water = C/m  T f = K f m m =m = moles of solute mass of solvent (kg) = 2.41 m = kg solvent 478 g x 1 mol g  T f = K f m = C/m x 2.41 m = C  T f = T f – T f 0 T f = T f –  T f 0 = C – C = C

Osmotic Pressure (  ) Osmosis is the selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one. A semipermeable membrane allows the passage of solvent molecules but blocks the passage of solute molecules. Osmotic pressure (  ) is the pressure required to stop osmosis. dilute more concentrated

High P Low P Osmotic Pressure (  )  = MRT M is the molarity of the solution R is the gas constant T is the temperature (in K)

A cell in an: isotonic solution hypotonic solution hypertonic solution

Colligative Properties of Nonelectrolyte Solutions Colligative properties are properties that depend only on the number of solute particles in solution and not on the nature of the solute particles. Vapor-Pressure Lowering P 1 = X 1 P 1 0 Boiling-Point Elevation  T b = K b m Freezing-Point Depression  T f = K f m Osmotic Pressure (  )  = MRT

Colligative Properties of Electrolyte Solutions 0.1 m NaCl solution 0.1 m Na + ions & 0.1 m Cl - ions Colligative properties are properties that depend only on the number of solute particles in solution and not on the nature of the solute particles. 0.1 m NaCl solution0.2 m ions in solution van’t Hoff factor (i) = actual number of particles in soln after dissociation number of formula units initially dissolved in soln nonelectrolytes NaCl CaCl 2 i should be 1 2 3

Boiling-Point Elevation  T b = i K b m Freezing-Point Depression  T f = i K f m Osmotic Pressure (  )  = iMRT Colligative Properties of Electrolyte Solutions

A colloid is a dispersion of particles of one substance throughout a dispersing medium of another substance. Colloid versus solution collodial particles are much larger than solute molecules collodial suspension is not as homogeneous as a solution

The Cleansing Action of Soap C 15 H 31 사슬 COO - 기

The Cleansing Action of Soap Grease Hydrophilic Head Hydrophobic Tail

Chemistry In Action: Desalination >26 bar

13 장 용액의 물리적 성질 - 요약 구성과 구성비 ( 농도 ) 용해와 용해도 총괄성

용액의 물리적 성질 - 균일 혼합물의 구성 용액 - 균일 혼합물 구성물 – 용매, 용질 구성비 – 농도 - 물리적 표현, 화학적 표현 농도 단위 - 몰 [M], 몰랄 (m), 몰분율 (X) 구성 한계 - 용해도

용액의 물리적 성질 - 용해 용해와 용해도 - 포화, 불포화, 과포화 용해과정의 분자적 고찰 - 용질, 용매 분자간 상호작용 용해도에 미치는 온도의 영향 - 재결정 기체의 용해도에 미치는 압력의 영향 – Henry’s Law 용해도에 미치는 온도의 영향 액체의 경우 - 재결정 기체의 경우

용액의 물리적 성질 - 총괄성 총괄성 – Raoult’s Law, van’t Hoff factor 분압, 끓는점 녹는점 삼투압 분별증류 분자량측정 역삼투