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1 SIFAT FISIKA LARUTAN. 2 Larutan : campuran homogen dari dua senyawa atau lebih Zarut : senyawa yang jumlahnya lebih sedikit (solute) Pelarut : Senyawa.

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Presentasi berjudul: "1 SIFAT FISIKA LARUTAN. 2 Larutan : campuran homogen dari dua senyawa atau lebih Zarut : senyawa yang jumlahnya lebih sedikit (solute) Pelarut : Senyawa."— Transcript presentasi:

1 1 SIFAT FISIKA LARUTAN

2 2 Larutan : campuran homogen dari dua senyawa atau lebih Zarut : senyawa yang jumlahnya lebih sedikit (solute) Pelarut : Senyawa yang jumlahnya lebih besar (solvent)

3 3 Larutan jenuh mengandung jumlah maksimum zarut yang dapat terlarut dalam jumlah pelarut tertentu pada temperatur spesifik Larutaan tidak jenuh mengandung jumlah zarut yang lebih kecil dari kapasitas pelarut pada temperatur spesifik Larutan super jenuh mengandung jumlah zarut yang lebih besar dari larutan jenuh pada temperatur spesifik Kristal CH 3 COONa sangat cepat terbentuk pada larutan super jenuh

4 4 Tiga tipe interaksi dalam proses pelarutan: Interaksi solven-solven Interaksi zarut-zarut Interaksi solven-zarut Mekanisme pembentukan larutan:  H soln =  H 1 +  H 2 +  H 3

5 5 “like dissolves like” Dua senyawa dengan gaya intermolekuler yang serupa akan melarutkan satu sama lain Molekul non-polar larut dalam pelarut non-polar CCl 4 dalam C 6 H 6 Molekular polar larut dalam pelarut polar C 2 H 5 OH dalam H 2 O Senyawa ionik lebih larut dalam pelarut polar NaCl dalam H 2 O atau NH 3 (l)

6 6 Konsentrasi Konsentrasi suatu larutan : jumlah zarut yang ada dalam jumlah tertentu pelarut atau larutan Persen Massa % massa = x 100% massa zarut massa zarut + massa pelarut = x 100% massa zarut massa larutan Fraksi Mol (X) X A = mol A Jumlah mol seluruh komponen

7 7 M = mol zarut volum larutan (L) Molaritas (M) Molalitas (m) m = mol zarut massa pelarut(kg)

8 8 Berapa molalitas 5.86 M larutan (C 2 H 5 OH) yang memiliki densitas g/mL? m =m = mol zarut massa pelarut (kg) M = mol zarut Volum larutan (L) Asumsi 1 L larutan: 5.86 mol etanol = 270 g etanol 927 g larutan (1000 mL x g/mL) massa pelarut = massa larutan – massa zarut = 927 g – 270 g = 657 g = kg m =m = mol zarut massa pelarut (kg) = 5.86 mol C 2 H 5 OH kg pelarut = 8.92 m

9 9 Temperatur and Kelarutan Kelarutan padatan and temperatur Kelarutan meningkat seiring peningkatan temperatur Kelarutan menurun seiring peningkata temperatur

10 10 Kristalisasi fraksional : pemisahan campuran senyawa menjadi senyawa murni berdasarkan perbedaan kelarutan Contoh: 90 g KNO 3 terkontaminasi oleh 10 g NaCl. Kristalisasi fraksional: 1.Larutkan sampel dalam 100 g air pada 60 0 C 2.Dinginkan larutan hingga 0 0 C 3.Seluruh NaCl akan tertinggal dalam larutan (s = 34.2g/100g) 4.78 g KNO 3 murni akan mengendap (s = 12 g/100g). 90 g – 12 g = 78 g

11 11 Temperatur dan Kelarutan Kelarutan gas O 2 dan temperatur Kelarutan biasanya menurun dengan peningkatan temperatur

12 12 Tekanan dan Kelarutan Gas Kelarutan gas dalam cairan proporsional terhadap tekanan gas pada larutan (Henry’s law). c = kP c : konsentrasi (M) gas terlarut P : tekanan gas dalam larutan k : konstanta setiap gas (mol/Latm) yang tergantung hanya pada temperatur low P low c high P high c

13 13 Chemistry In Action: The Killer Lake Lake Nyos, West Africa 21/08/86 Awan CO 2 dilepaskan 1700 korban Penyebab? Gempa bumi Tanah longsor Angin kencang

14 14

15 15 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 = vapor pressure of pure solvent X 1 = mole fraction of the solvent X 2 = mole fraction of the solute P 1 = X 1 P 1 0

16 16 P A = X A P A 0 P B = X B P B 0 P T = P A + P B P T = X A P A 0 + X B P B 0 Ideal Solution

17 17 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 >&

18 18 Fractional Distillation Apparatus

19 19 Boiling-Point Elevation  T b = T b – T b 0 T b > T b 0  T b > 0 T b is the boiling point of the pure solvent 0 T b is the boiling point of the solution  T b = K b m m is the molality of the solution K b is the molal boiling-point elevation constant ( 0 C/m) for a given solvent

20 20 Freezing-Point Depression  T f = T f – T f 0 T f > T f 0  T f > 0 T f is the freezing point of the pure solvent 0 T f is the freezing point of the solution  T f = K f m m is the molality of the solution K f is the molal freezing-point depression constant ( 0 C/m) for a given solvent

21 21

22 22 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.  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 K f water = 1.86 o C/m  T f = K f m = 1.86 o C/m x 2.41 m = 4.48 o C  T f = T f – T f 0 T f = T f –  T f 0 = 0.00 o C – 4.48 o C = o C

23 23 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

24 24 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) solvent solution time

25 25 A cell in an: isotonic solution hypotonic solution hypertonic solution

26 26 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

27 27 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

28 28 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

29 29 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 colloids exhibit the Tyndall effect

30 30

31 31 Hydrophilic and Hydrophobic Colloids Hydrophilic: water-loving Hydrophobic: water-fearing Stabilization of a hydrophobic colloid

32 32 The Cleansing Action of Soap

33 33 Chemistry In Action: Desalination

34 34 Chemistry In Action: Reverse Osmosis


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