Chemistry B 11 Chapter 9 Solutions and Colloids

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

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

Solutions (liquid in liquid) Solvent: greater quantity (water) for liquid in liquid Solute: smaller quantity (sugar) Immiscible: 2 liquids that don’t mix. miscible: 2 liquids that mix. (in any quantities) alcohol in water

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 Supersaturated solution Seeding A surface on which to begin crystallizing.

gas in liquid: T ↑ Solubility ↓ Global Warming

Pressure and Solutions Henry’s law P Solubility (gas in liquid) More pressure more interactions with the liquid

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

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

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

Concentration 3. Parts per Million (ppm): g solute ppm = × 106 g solvent Parts per billion (ppb): ppb = g solute × 109 g solvent

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 M 1 V 1/V 2 = M 2

Equivalents Number of Equivalents (Eq) in 1 mole of each ion is number of charge on that ion. Ion Charge # of Equivalents in 1 mole Na+ 1+ 1 Eq Ca 2+ 2+ 2 Eq Fe 3+ 3+ 3 Eq Cl- 1 - 1 Eq SO 42 - 2 - 2 Eq

Equivalents Ex. 1: How many equivalents of CO 32 - are in 1 mole of Al 2(CO 3)3? The charge of CO 32 - is 2 - → 1 mole Al 2(CO 3)3 has 6 Eq CO 32 -. 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 6 Eq. 5 moles: 5 × 6 = 30 Eq

Water in our body 1. About 60% mass 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 Ions Hydrated by H 2 O Hydration like dissolves like

Solvent and Solute All nitrates (NO 3 -) and acetate (CH 3 COO-) are soluble in water. Most chlorides (Cl-) and sulfates (SO 42 -) are soluble in water. (except Ag. Cl, Ba. SO 4, and …) Most carbonates (CO 32 -), phosphates (PO 43 -) and hydroxides (OH-) are insoluble in water. (except Na. OH, Li. OH, KOH, and NH 4 OH)

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

Colloids Solutions: diameter of the solute particles is under 1 nm (10 -9) 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 passing through a colloid. (particles scatter light. ) emulsion: a mixture of immiscible substances (liquid-liquid). (milk and mayonnaise)

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

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 bp If we dissolve a solute in a solvent: ΔT = ik. M fp ΔT: change of bp or fp (T 2 - T 1) i: number of particles K: constant (depend on solute) – Kb Kf M: molarity Na. Cl Na+ + Cl- i=2 K 2 SO 4 2 K+ + SO 42 - i=3 C 2 H 6 O (Ethanol) i=1

Osmotic Pressure Semipermeable membrane osmotic pressure 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 ↑

Isotonic solution Equal Hypotonic solution Hypertonic solution Water in Hemolysis Water out Crenation

The most typical isotonic solutions 0. 9% (m/v) Na. Cl 5% (m/v) Glucose 0. 9 g Na. Cl/100 m. L of solution 5 g glucose/100 m. L of solution Higher than these numbers → Hypertonic solution Lower than these numbers → Hypotonic solution

Dialysis Dilute solution