Chapter 6 Solutions and Colloids Chemistry B11

Mixture: is a combination of two or more pure substances. Homogeneous: uniform and throughout Air, Salt in water Heterogeneous: nonuniform Soup, Milk, Blood Mixtures Solution

Solutions Gas in gas (air) solid in solid (alloys) liquid in liquid (alcohol in water) Gas in liquid (cokes)solid in liquid (sugar in water) Solutions Well-mixed (uniform) – single phase homogenous transparent cannot be separated by filtration cannot be separated on standing sugar in water

Solutions (liquid in liquid) Solvent: greater quantity (water) Solute: smaller quantity (sugar) Immiscible: two liquids do not mix. miscible: two liquids can mix. alcohol in water (in any quantities) for liquid in liquid

Solutions Saturated: solvent contains or holds all the solute it can (at a given T). maximum solute that solvent can hold (Equilibrium). Unsaturated: solvent can hold more solute (at a given T). Is not the maximum solute that solvent can hold. Supersaturated: solvent holds more solute that it can normally hold (at a given T). (more than an equilibrium condition)

Temperature and Solutions Solubility: the maximum solute that will dissolve in a given amount of a solvent (at a given T). T  Solubility  T  Crystal is formed

Temperature and Solutions T  Solubility  Seeding A surface on which to being crystallizing. Supersaturated solution

gas in liquid: T ↑ Solubility ↓ Global Warming

Pressure and Solutions P  Solubility  (gas in liquid) Henry’s law

Concentration Concentration: amount of a solute dissolved in a given quantity of solvent. 1. Percent concentration: Weight / volume (W / V)% = Weight solute Volume of solution (mL) × 100 Weight / Weight (W / W)% = Weight solute Weight of solution × 100 Volume / volume (V / V)% = Volume solute (mL) Volume of solution (mL) × 100

2. Molarity (M): number of moles solute dissolved in 1 L of solution. Concentration Molarity (M) = moles solute (n) volume of solution (L) Molarity × V = number of moles (n) prepare the solution: M, V → n (mol) → m (g)

Prepare the solution prepare the solution: M, V → n (mol) → m (g) m (g) Volumetric flask

3. Parts per Million (ppm): Concentration ppm = g solute g solvent × 10 6 Parts per billion (ppb): ppb = g solute g solvent × 10 9

Dilution Concentrated solution (Stock solution) Dilute solution

Dilution M 1 V 1 = moles(n)before dilution M 2 V 2 = moles(n)after dilution M 1 V 1 = M 2 V 2 % V 1 = % V 2

Equivalent Number of Equivalents (Eq) in 1 mole of each ion is number of charges of that ion. IonCharge# of Equivalents in 1 mole Na Eq Ca Eq Fe Eq Cl Eq SO Eq

Equivalent Ex. 1: How many equivalents of CO 3 2- are in 1 mole of Al 2 (CO 3 ) 3 ? The charge of CO 3 2- is 2- → 1 mole Al 2 (CO 3 ) 3 has 2 Eq CO Ex. 2: How many equivalents of Fe 3+ are in 5 mole of Fe 2 O 3 ? The charge of Fe 3+ is 3+ → 1 mole Fe 2 O 3 has 3 Eq. 5 moles: 5 × 3 = 15 Eq

Water in our body 1.About 60% of our body. 2.Most of the reactions occur in aqueous solution. 3.Participates in many biochemical reactions. 4.Transports reactants and products from one place in our body to another. 5. Eliminates the waste materials from cells and our body (urine).

Solvent and Solute polar dissolves polar Nonpolar dissolves nonpolar like dissolves like Ions Hydrated by H 2 O Hydration

Solvent and Solute Most chlorides (Cl - ) and sulfates (SO 4 2- ) are soluble in water. (except AgCl, BaSO 4, and …) Most carbonates (CO 3 2- ), phosphates (PO 4 3- ) and hydroxides (OH - ) are insoluble in water. (except NaOH, LiOH, KOH, and NH 4 OH) All nitrates (NO 3 - ) and acetate (CH 3 COO - ) are soluble in water.

Electrolytes +- electrolyte Electrolyte: conducts an electric current. strong electrolytes: molecules dissociate completely into ions (NaCl). weak electrolytes: molecules dissociate partially into ions (CH 3 COOH). nonelectrolytes: molecules do not dissociate into ions (DI water). NaCl → Na + + Cl - Na + Cl - bulb Ionization ( Dissociation)

Colloids Solutions: diameter of the solute particles is under 1 nm. Colloids: diameter of the solute particles is between 1 to 1000 nm. non transparent, non uniform, large particles, cloudy (milky) but a stable system

Colloids Tyndall effect: You can see the pathway of the light passes through a colloid. (particles scatter light.) emulsion: a mixture of immiscible substances (liquid-liquid). (milk and mayonnaise)

suspension: system does not stays stable and settle (> 1000 nm). (sand in water) Suspension

Brownian motion Random motion of colloid particles. Dust Why do colloidal particles remain in solution and do not stick together? 1. Surrounding water molecules prevent colloidal molecules from touching and sticking together. 2. A charged colloidal particle encounters another particle of the same charge, they repel each other.

Freezing and boiling point If we dissolve a solute in a solvent: bp  fp  ΔT = ikM ΔT: change of bp or fp (T 2 - T 1 ) i: number of particles K: constant (depend on solute) – K b K f M: molarity NaCl  Na + + Cl - i = 2 C2H6O2C2H6O2 i = 1 K 2 SO 4  2K + + SO 4 2- i = 3

osmotic pressure Osmotic Pressure Semipermeable membrane Higher concentration → Higher osmotic pressure

Osmotic Pressure Water flows from low concentration to high concentration.

Osmotic Pressure Osmolarity (osmol) = M × i M: molarity i: number of particles Osmolarity ↑ → Osmotic pressure ↑

HemolysisCrenation Isotonic solution Hypotonic solutionHypertonic solution

The most typical isotonic solutions 0.9% (m/v) NaCl 5% (m/v) Glucose 0.9 g NaCl/100 mL of solution 5 g glucose/100 mL of solution Higher than these numbers → Hypertonic solution Lower than these numbers → Hypotonic solution

Dialysis Dilute solution