Solutions Table of Contents ‘Solutions’ Chemical Stewardship Solutions Effect of Temperature… Process of Dissolving Electrolytes Colligative Properties Solubility Curve Dilution of Solutions Polarity of Solutions Soap Making Reverse Osmosis Bonding Hard Water Objectives • To be familiar with the kinetic molecular description of liquids • To be able to describe the intermolecular forces in liquids • To be able to describe the unique properties of liquids • To know how and why the vapor pressure of a liquid varies with temperature • To be able to calculate the energy changes that accompany phase changes • To know what is meant by the critical temperature and pressure of a liquid • To understand the general features of a phase diagram Chemical Stewardship • Be responsible in how you dispose of and use chemicals. • Chemical pollution can travel far – and harm organisms. Frog with three legs – it has mutated from chemical exposure. Early Warning Signs… = Contamination of water where frog lives causes mutations. Canary dies in the mine from bad air (cyanide). This is clue for miners to leave the mine…alive. Pfiesteria Pfiesteria organism Fish sores from infection by pfiesteria. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside …………………………………………………………………………………………… t.r.p.s odorless lacquer methyl ethyl acetone mineral boiled turpentine specs brush naptha xylol adhesive paint thinner thinner ketone spirits linseed oil paint thinner cleaner remover …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside …………………………………………………………………………………………… t.r.p.s lacquer methyl ethyl acetone boiled turpentine brush naptha specs xylol adhesive odorless mineral thinner ketone linseed oil cleaner paint thinner remover paint thinner spirits …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… paint thinner paint thinner paint thinner LATEX kerosene kerosene kerosene paint thinner …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………................. ……………… …store. Solvents at the hardware Solvents at the hardware store sunnyside specs paint thinner sunnyside specs paint thinner sunnyside sunnyside sunnyside naptha naptha mineral spirits sunnyside sunnyside sunnyside naptha naptha mineral spirits sunnyside sunnyside sunnyside mineral odorless odorless spirits paint thinner paint thinner sunnyside sunnyside sunnyside mineral odorless odorless spirits paint thinner paint thinner sunnyside sunnyside sunnyside sunnyside turpentine xylol lacquer thinner sunnyside sunnyside sunnyside sunnyside t.r.p.s. turpentine xylol t.r.p.s. lacquer thinner sunnyside sunnyside lacquer thinner acetone sunnyside sunnyside lacquer thinner acetone sunnyside methyl ethyl ketone sunnyside methyl ethyl ketone sunnyside sunnyside boiled linseed oil sunnyside boiled linseed oil sunnyside sunnyside brush cleaner adhesive remover sunnyside sunnyside sunnyside carbo-sol carbo-sol carbo-sol brush cleaner Glass Cleaner sunnyside adhesive remover Glass Cleaner Glass Cleaner sunnyside made-up stuff denatured alcohol solvent denatured alcohol solvent sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside sunnyside 1 GAL 1 GAL 1 GAL 2GAL 1 GAL 1 GAL 2 GAL 2 GAL muriatic acid Cool Stuff Juice Mr. C’s sweat! sunnyside muriatic acid muriatic acid sunnyside muriatic acid Definitions • Solution - homogeneous mixture Solute - substance being dissolved Solvent - present in greater amount Solutions • What the solute and the solvent are determines –whether a substance will dissolve. –how much will dissolve. • A substance dissolves faster if it is stirred or shaken. –The particles are made smaller. –The temperature is increased. Why? Solution = Solute + Solvent • Solute - gets dissolved • Solvent - does the dissolving – Aqueous – Tincture – Amalgam – Organic • Polar • Non-polar (water) (alcohol) (mercury) Dental filling Nightmare on White Street Chem Matters, December 1996 Solution Definitions solution: a homogeneous mixture -- evenly mixed at the particle level -- e.g., salt water alloy: a solid solution of metals -- e.g., bronze = Cu + Sn; brass = Cu + Zn solvent: the substance that dissolves the solute water salt soluble: “will dissolve in” miscible: refers to two gases or two liquids that form a solution; more specific than “soluble” -- e.g., food coloring and water Types of Solutions Solute Solvent Solution gas gas air (nitrogen, oxygen, argon gases) humid air (water vapor in air) liquid liquid liquid carbonated drinks (CO2 in water) vinegar (CH3COOH in water) salt water (NaCl in water) solid solid dental amalgam (Hg in Ag) sterling silver (Cu in Ag) Gaseous Solutions gas liquid Liquid Solutions gas liquid solid Solid Solutions liquid solid Charles H.Corwin, Introductory Chemistry 2005, page 369 Factors Affecting the Rate of Dissolution 1. temperature 2. particle size 3. mixing 4. nature of solvent or solute As To , rate As size , rate More mixing, rate Classes of Solutions aqueous solution: solvent = water water = “the universal solvent” amalgam: solvent = Hg e.g., dental amalgam tincture: solvent = alcohol e.g., tincture of iodine (for cuts) organic solution: solvent contains carbon e.g., gasoline, benzene, toluene, hexane Non-Solution Definitions insoluble: “will NOT dissolve in” e.g., sand and water immiscible: refers to two gases or two liquids that will NOT form a solution e.g., water and oil suspension: appears uniform while being stirred, but settles over time Solubility Experiment 1: Add 1 drop of red food coloring Before AFTER Miscible – “mixable” two gases or two liquids that mix evenly Water Water Water Water COLD HOT COLD HOT B A B A Solubility Experiment 2: Add oil to water and shake AFTER Before Immiscible – “does not mix” two liquids or two gases that DO NOT MIX Oil Water Water T0 sec T30 sec Muddy Water: Dissolved Solids Experiment 3: Add soil to water, shake well, and allow to settle AFTER Before Dissolved solids can be calculated as a percentage: v/v (volume/volume) w/v (weight/volume) w/w (weight/weight) Muddy Water Water 5% v/v soil in water 5 mL solid / 95 mL water T1 min T5 min 5 mL / 100 mL = 5% Muddy Water: Flocculation Al2(SO4)3 + 3 Ca(OH)2 2 Al(OH)3 + 3 CaSO4 Experiment 4: Add soil to water, shake well, and allow to settle AFTER AFTER Before Before Muddy Muddy Water Water Water T1 min T15 min NO Flocculation material Water T1 min T5 min WITH Flocculation material Centrifugation • Spin sample very rapidly: denser materials go to bottom (outside) • Separate blood into serum and plasma – Serum (clear) – Plasma (contains red blood cells ‘RBCs’) AFTER Before Serum Blood RBC’s • Check for anemia (lack of iron) A B C Making solutions • In order to dissolve - the solvent molecules must come in contact with the solute. • Stirring moves fresh solvent next to the solute. • The solvent touches the surface of the solute. • Smaller pieces increase the amount of surface of the solute. Water Molecule Water is a POLAR molecule d+ H2O d- d+ H+ H+ O2- d- Water molecules “stick” together to create surface tension to support light weight objects. Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Water Molecule • What is a polar molecule? dHydrogen bond d+ H • How does the polarity of water effect this molecule? O H • Hydrogen bonds occur between two polar molecules, or between different polar regions of one large macromolecule. • One “relatively” negative region is attracted to a second “relatively” positive region. H O Electronegative atoms H Hydrogen bond N H H H Interstitial Spaces Oil Oil Oil Oil Oil Oil Oil Non-polar "immiscible" Layer dissolved solid Water Water Water Water Water Water Water Water Polar red food coloring Interstitial Spaces Oil Oil Oil Oil Oil Oil Oil Non-polar "immiscible" Layer dissolved solid Water Water Water Water Water Water Water Water Polar red food coloring Dissolving of solid NaCl Polar water molecules interact with positive and negative ions Animation Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 468 Dissolving of solid NaCl Na+ ClCl- salt Na+ Cl- Na+ NaCl solid (aq) = Na+ Animation by Raymond Chang All rights reserved. = Cl- Solvation Solvation – the process of dissolving solute particles are surrounded by solvent particles solute particles are separated and pulled into solution Dissolving of NaCl H H O Na+ + + + + + - - hydrated ions - Cl- Timberlake, Chemistry 7th Edition, page 287 + - Dissolving of Salt in Water Na+ ions Water molecules Clions NaCl(s) + H2O Na+(aq) + Cl-(aq) Dissolving of Salt in Water Na+ ions Water molecules Clions NaCl(s) + H2O Na+(aq) + Cl-(aq) Particle Model of a Solution Before mixing Fresh water Water molecule After mixing Saltwater solution Water molecule Chloride ion, Cl- Sodium ion, Na+ Solubility vs. Temperature Solubility (g solute / 100 g H2O) 200 180 160 140 120 100 80 60 NaCl 40 20 0 20 40 60 Temperature (oC) Timberlake, Chemistry 7th Edition, page 297 80 100 Gas Solubility CH4 2.0 Solubility (mM) O2 CO 1.0 He 0 10 20 30 Temperature (oC) 40 50 Solubility Rules General Rules for Solubility of Ionic Compounds (Salts) in Water at 25 oC 1. Most nitrate (NO31-) salts are soluble. 2. Most salts of Na+, K+, and NH4+ are soluble. 3. Most chloride salts are soluble. Notable exceptions are AgCl, PbCl2, and Hg2Cl2. 4. Most sulfate salts are soluble. Notable exceptions are BaSO4, PbSO4, and CaSO4. 5. Most hydroxide compounds are only slightly soluble.* The important exceptions are NaOH and KOH, Ba(OH)2 and Ca(OH)2 are only moderately soluble. 6. Most sulfide (S2-), carbonate (CO32-), and phosphate (PO43-) salts are only slightly soluble. *The terms insoluble and slightly soluble really mean the same thing. Such a tiny amount dissolves that it is not possible to detect it with the naked eye. Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 218 Solubility of Common Compounds Soluble compounds NO3- salts Na+, K+, NH4+ salts Cl-, Br-, I- salts Except for Ag+, Hg22+, Pb2+ those containing SO42- salts Except for 2+, Pb2+, Ca2+ Ba those containing Insoluble compounds S2-, CO32-, PO43- salts OH1- salts Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 218 Except for those containing Na+, K+, Ca2+ Temperature-Solubility Relationships* 190 CsCl 180 NaNO3 Solubility in grams per 100 g of water 170 160 NaC2H3O2 150 140 130 RbCl 120 LiCl 110 100 90 80 NH4Cl 70 60 KCl 50 NaCl 40 30 Li2SO4 20 10 SO2 0 0 10 20 30 40 50 60 70 80 90 100 Temperature (oC) *Values on this graph are valid only when some undissolved solid is in contact with the solution. For SO2 values are valid when pressure due to SO2 and water vapor is 101.325 kPa. Pure water does not conduct an electric current Source of electric power Pure water Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 215 Ionic Solutions conduct a Current Source of electric power Free ions present in water Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 215 Electrolytes (a) Nonelectrolyte Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. (b) Weak electrolyte (c) Strong electrolyte Electrolytes Electrolytes - solutions that carry an electric current strong electrolyte NaCl(aq) Na+ + Cl- Timberlake, Chemistry 7th Edition, page 290 weak electrolyte HF(aq) H+ + F- nonelectrolyte Structure of Sucrose • Table sugar • C6H12O6 H C HO CH2OH O C H OH C H H C OH H H CH2OH O C H C OH C CH2OH C C O OH Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 469 H Korey Stringer 1974 - 2001 Korey Stringer was a professional football player for the Minnesota Vikings. He collapsed during practice from excessive heat and died the following day. Electrolyte Imbalances Electrolyte Normal range (mmol / L) Excess Defiency Sodium Na+ 135 - 145 Hypernatremia (increased urine excretion; excess water loss) Hyponatremia (dehydration; diabetesrelated low blood pH; vomiting, diarrhea) Potassium K+ 3.5 – 5.0 Hyperkalemia (renal failure, low blood pH) Hypokalemia (gastointestinal conditions) Hydrogen carbonate HCO3- 24 - 30 Hypercapina (high blood pH; hypoventilation) Hypocapnia (low blood pH; hyperventilation; dehydration) Chloride Cl- 100 - 106 Hyperchloremia (anemia, heart conditions, dehydration) Hypochloremia (acute infections; burns; hypoventilation) Effect of Salinity on Cells no change isotonic solution hemolysis hypotonic solution crenation Timberlake, Chemistry 7th Edition, page 312 hypertonic solution Isotonic (a) Cells in dilute salt solution Hypotonic (b) Cells in distilled water Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Hypertonic (c) Cells in concentrated salt solution Concentration = #1offish fish volume 1 (L) (L) Concentration = 1 “fishar” V = 1000 mL V = 1000 mL V = 5000 mL n = 2 fish n = 4 fish n = 20 fish Concentration = 2 “fishar” [ ] = 4 “fishar” [ ] = 4 “fishar” Concentration = # of moles volume (L) V = 250 mL n = 8 moles [ ] = 32 molar V = 1000 mL V = 1000 mL V = 5000 mL n = 2 moles n = 4 moles n = 20 moles Concentration = 2 molar [ ] = 4 molar [ ] = 4 molar Making Molar Solutions …from liquids (More accurately, from stock solutions) Concentration…a measure of solute-to-solvent ratio concentrated “lots of solute” vs. dilute “not much solute” “watery” Add water to dilute a solution; boil water off to concentrate it. remove sample moles of solute initial solution Making a Dilute Solution mix same number of moles of solute in a larger volume diluted solution Timberlake, Chemistry 7th Edition, page 344 Concentration “The amount of solute in a solution” A. mass % = mass of solute mass of sol’n % by mass – medicated creams % by volume – rubbing alcohol B. parts per million (ppm) also, ppb and ppt – commonly used for minerals or contaminants in water supplies C. molarity (M) = moles of solute L of sol’n mol – used most often in this class M = D. mol L molality (m) = moles of solute kg of solvent M L ppm 1 inch in 16 miles ppb 1 inch in 16,000 miles ppt 1 sec = 32,000 years Glassware Glassware – Precision and Cost beaker vs. volumetric flask When filled to 1000 mL line, how much liquid is present? beaker 5% of 1000 mL = 50 mL volumetric flask 1000 mL + 0.30 mL Range: 950 mL – 1050 mL Range: 999.70 mL– 1000.30 mL imprecise; cheap precise; expensive Markings on Glassware Beaker 500 mL + 5% Range = 500 mL + 25 mL 475 – 525 mL Graduated Cylinder 1000 mL + 5 mL Range = 1000 mL + 5 mL 475 – 525 mL Volumetric Flask 500 mL + 0.2 mL Range = 499.8 – 500.2 mL TC 20oC “to contain at a temperature of 20 oC” TD “to deliver” 22 s T “time in seconds” water in grad. cyl. mercury in grad. cyl. ~ ~ ~ ~ ~ ~ ~ ~ Measure to part of meniscus w/zero slope. Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. How to mix solid chemicals Lets mix chemicals for the upcoming soap lab. We will need 1000 mL of 3 M NaOH per class. How much sodium hydroxide will I need, for five classes, for this lab? mol M = L ? mol 3M = 1L How much will this weigh? ? = 3 mol NaOH/class x 5 classes 15 mol NaOH 1 Na @ 23g/mol + 1O @ 16g/mol + 1 H @ 1 g/mol MMNaOH = 40g/mol X g NaOH = 15.0 mol NaOH 40.0 g NaOH = 600 g NaOH 1 mol NaOH FOR EACH CLASS: To mix this, add 120 g NaOH into 1L volumetric flask with ~750 mL cold H2O. Mix, allow to return to room temperature – bring volume to 1 L. How to mix a Standard Solution Wash bottle Volume marker (calibration mark) Weighed amount of solute Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 480 How to mix a Standard Solution http://www.chem.ucla.edu/~gchemlab/soln_conc_web.htm Process of Making a Standard Solution from Liquids Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 483 How to mix a dilute solution from a concentrated stock solution Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Reading a pipette Identify each volume to two decimal places (values tell you how much you have expelled) 4.48 - 4.50 mL 4.86 - 4.87 mL 5.00 mL www.chalkbored.com Dilution of Solutions Molarity Reagent Percent To Prepare 1 Liter of one molar Solution 1.05 17.45 99.8% 57.3 mL 35.05 0.90 14.53 56.6% 69.0 mL Formic Acid (HCOOH) 46.03 1.20 23.6 90.5% 42.5 mL Hydrochloric Acid (HCl) 36.46 1.19 12.1 37.2% 82.5 mL Hydrofluoric Acid (HF) 20.0 1.18 28.9 49.0% 34.5 mL Nitric Acid (HNO3) 63.01 1.42 15.9 70.0% 63.0 mL Perchloric Acid 60% (HClO4) 100.47 1.54 9.1 60.0% 110 mL Perchloric Acid 70% (HClO4) 100.47 1.67 11.7 70.5% 85.5 mL Phosphoric Acid (H3PO4) 97.1 1.70 14.8 85.5% 67.5 mL Potassium Hydroxide (KOH) 60.05 1.05 17.45 99.8% 57.3 mL Sodium Hydroxide (NaOH) 40.0 1.54 19.4 45.0% 85.5 mL Sulfuric Acid (H2SO4) 98.08 1.84 18.0 50.5% 51.5 mL Solution Guide Formula Weight Specific Gravity Acetic Acid Glacial (CH3COOH) 60.05 Ammonium Hydroxide (NH4OH) MConc.VConc. = MDiluteVDilute Dilutions of Solutions Acids (and sometimes bases) are purchased in concentrated form (“concentrate”) and are easily diluted to any desired concentration. **Safety Tip: When diluting, add acid or base to water.** Dilution Equation: MC VC MD VD C = concentrate D = dilute Concentrated H3PO4 is 14.8 M. What volume of concentrate is required to make 25.00 L of 0.500 M H3PO4? MC VC MD VD 14.8 M (VC ) 0.500 M (25.00 L) VC = 0.845 L = 845 mL How would you mix the above solution? 1. Measure out 0.845 L of concentrated H3PO4 . 2. In separate container, obtain ~20 L of cold H2O. 3. In fume hood, slowly pour [H3PO4] into cold H2O. 4. Add enough H2O until 25.00 L of solution is obtained. Be sure to wear your safety glasses! You have 75 mL of conc. HF (28.9 M); you need 15.0 L of 0.100 M HF. Do you have enough to do the experiment? MCVC = MDVD 28.9 M (0.075 L) = 0.100 M (15.0 L) Yes; we’re OK. 2.1675 mol HAVE > 1.50 mol NEED Dilution • Preparation of a desired solution by adding water to a concentrate. • Moles of solute remain the same. M1V1 M 2V2 Dilution • What volume of 15.8M HNO3 is required to make 250 mL of a 6.0M solution? GIVEN: M1 = 15.8M V1 = ? M2 = 6.0M V2 = 250 mL WORK: M1 V1 = M2 V2 (15.8M) V1 = (6.0M)(250mL) V1 = 95 mL of 15.8M HNO3 Preparing Solutions How to prepare 500 mL of 1.54 M NaCl solution – mass 45.0 g of NaCl – add water until total volume is 500 mL – Shake to dissolve salt 500 mL mark 45.0 g NaCl solute 500 mL volumetric flask Preparing Solutions molality molarity 1.54m NaCl in 0.500 kg of water 500 mL of 1.54M NaCl – mass 45.0 g of NaCl – add 0.500 kg of water – mass 45.0 g of NaCl – add water until total volume is 500 mL 500 mL water 45.0 g NaCl 500 mL mark 500 mL volumetric flask Spec-20 Instrument Sample holder cover Amplifier control knob Light control knob Wavelength control knob Spec-20 Absorbance Insert Photograph Spec-20 Meter Wavelength control 100 % Absorbance 0 % Transmittance Wavelength scale Sample-holder Light control Zero adjust and power control Absorbance 0 % Absorbance 100 % Transmittance l (wavelength) Schematic representation of a spectrophotometer I Io Monochromator Light Source (1) Detector Meter Sample cell (2) (5) (4) (3) A spectrophotometer is an instrument that measures the fraction (I/Io) of an incident beam of light (Io) which is transmitted (I) by a sample at a particular wavelength. Meter For a given substance, the amount of light absorbed depends on: a) the concentration; b) the cell or path length; c) the wavelength of light; and d) the solvent. Wavelength control Wavelength scale Sample-holder Light control Zero adjust and power control Absorbance of Chlorophyll 1.5 Frequency (Hz) 1026 cosmic rays 1.2 10-8 1022 1024 gamma rays 10-4 10-6 1020 1018 x-rays 10-2 1016 ultraviolet 1 102 1010 1014 106 108 infraradio radar tele- radio red (microwave) vision 104 106 108 1010 1012 102 104 power transmission 1014 1016 Absorbance Wavelength (nm) UV 0.9 Violet 400 nm Blue Green Yellow Orange Red 700 nm 600 nm 500 nm 0.6 0.3 0.0 300 400 500 600 Wavelength (nm) 700 800 1 Near Infrared Amount absorbed 400 663 nm 500 600 Wavelength (nm) Kelter, Carr, Scott, , Chemistry: A World of Choices 1999, page 480 700 Calibration Curve (fixed wavelength) 100 % Absorbance 0 % Transmittance ? Absorbance 0 % Absorbance 100 % Transmittance x2 out of linear range (too concentrated) Concentration Dilute sample with water 50:50. Run sample, read concentration. What mass of CaF2 must be added to 1,000 L of water so that fluoride atoms are present at a conc. of 1.5 ppm? X m’cule H2O = 1000 L 1000 mL 1 g 1 mol 1L 1 mL 18 g 6.02 x1023 m’cule = 3.34 x 1028 m’cules H2O 1 mol 1.5 atom F X atoms F = 1,000,000 m’cule H2O 3.34 x 1028 m’cule H2O X = 5.01 x 1022 atoms F times X g CaF2 = 2.505 x 1022 molecules 1 molecule CaF2 2 atoms F 1 mol CaF2 6.02 x 1023 molecules = 2.505 x 1022 molecules CaF2 78.1 g CaF2 = 3.25 g CaF2 1 mol CaF2 mol M L How many moles solute are required to make 1.35 L of 2.50 M solution? mol = M L = 2.50 M (1.35 L) = 3.38 mol A. What mass sodium hydroxide is this? X g NaOH = 3.38 mol NaOH 40.0 g NaOH = 1 mol NaOH 135 g NaOH B. What mass magnesium phosphate is this? X g Mg3(PO4)2 = 3.38 mol Mg3(PO4)2 262.9 g Mg3(PO4)2 = 889 g Mg3(PO4)2 1 mol Mg3(PO4)2 Find molarity if 58.6 g barium hydroxide are in 5.65 L solution. Step 1). How many moles barium hydroxide is this? X mol Ba(OH)2 = 58.6 g Ba(OH)2 1 mol Ba(OH)2 171.3 g Ba(OH)2 = 0.342 mol Ba(OH)2 Step 2). What is the molarity of a 5.65 L solution containing 0.342 mol solute? M = mol L M = 0.342 mol 5.65 L = 0.061 M Ba(OH)2 1mol Ba(OH) 2 58.6 g Ba(OH) 2 171.3 g Ba(OH) 2 XM 5.65 L 0.061 M Ba(OH) 2 You have 10.8 g potassium nitrate. How many mL of solution will make this a 0.14 M solution? 1 mol 10.8 g KNO 3 101.1 g 0.763 L 1000 mL XL 0.140 M 1 L 76.3 mL convert to mL Molality moles of solute molality (m) kg of solvent 0.25 mol 0.25m 1 kg mass of solvent only 1 kg water = 1 L water Dissociation occurs when neutral combinations of particles separate into ions while in aqueous solution. sodium chloride NaCl Na1+ + Cl1– sodium hydroxide NaOH Na1+ + OH1– hydrochloric acid HCl H1+ + Cl1– sulfuric acid H2SO4 2 H1+ + SO42– acetic acid CH3COOH CH3COO1– + H1+ In general, acids yield hydrogen (H?1+) ions ? 1–) ions. in aqueous solution; bases yield hydroxide (OH Strong electrolytes exhibit nearly 100% dissociation. NOT in water: in aq. solution: NaCl 1000 1 Na1+ 0 999 + Cl1– 0 999 Weak electrolytes exhibit little dissociation. CH3COOH NOT in water: in aq. solution: 1000 980 CH3COO1– 0 20 + H1+ 0 20 “Strong” or “weak” is a property of the substance. We can’t change one into the other. electrolytes: solutes that dissociate in solution -- conduct electric current because of free-moving ions e.g., acids, bases, most ionic compounds -- are crucial for many cellular processes -- obtained in a healthy diet -- For sustained exercise or a bout of the flu, sports drinks ensure adequate electrolytes. nonelectrolytes: solutes that DO NOT dissociate -- DO NOT conduct electric current (not enough ions) e.g., any type of sugar Colligative Properties depend on concentration of a solution Compared to solvent’s… a solution w/that solvent has a… …normal freezing point (NFP) …lower FP …normal boiling point (NBP) …higher BP FREEZING PT. DEPRESSION BOILING PT. ELEVATION Applications (NOTE: Data are fictitious.) 1. salting roads in winter FP water 0oC (NFP) water + a little salt –11oC water + more salt –18oC BP 100oC (NBP) 103oC 105oC 2. antifreeze (AF) /coolant FP water 0oC (NFP) BP 100oC (NBP) water + a little AF –10oC 110oC 50% water + 50% AF –35oC 130oC 3. law enforcement starts melting at… finishes melting at… penalty, if convicted A 109oC 175oC comm. service B 150oC 180oC 2 years C 194oC 196oC 20 years white powder Effect of Pressure on Boiling Point Boiling Point of Water at Various Locations Feet Boiling Patm Location above Point (kPa) (C) sea level Top of Mt. Everest, Tibet 29,028 32 70 Top of Mt. Denali, Alaska 20,320 45.3 79 Top of Mt. Whitney, California 14,494 57.3 85 Leadville, Colorado 10,150 68 89 Top of Mt. Washington, N.H. 6,293 78.6 93 Boulder, Colorado 5,430 81.3 94 Madison, Wisconsin 900 97.3 99 New York City, New York 10 101.3 100 -282 102.6 100.3 Death Valley, California Calculations for Colligative Properties The change in FP or BP is found using… DTx = Kx m i DTx = change in To (below NFP or above NBP) Kx = constant depending on… (A) solvent (B) freezing or boiling m = molality of solute = mol solute / kg solvent i = integer that accounts for any solute dissociation any sugar (all nonelectrolytes)……………...i = 1 table salt, NaCl Na1+ + Cl1–………………i = 2 barium bromide, BaBr2 Ba2+ + 2 Br1–……i = 3 Freezing Point Depression DTf = Kf m i Boiling Point Elevation DTb = Kb m i Then use these in conjunction with the NFP and NBP to find the FP and BP of the mixture. (Kf = cryoscopic constant, which is 1.86 K kg/mol for the freezing point of water) (Kb = ebullioscopic constant, which is 0.51 K kg/mol for the boiling point of water) 168 g glucose (C6H12O6) are mixed w/2.50 kg H2O. Find BP and FP of mixture. For H2O, Kb = 0.512, Kf = –1.86. i=1 (NONELECTROLYTE) 168 g mol C 6H12 O 6 180 g m 0.373 m kg H2O 2.50 kg DTb = Kb m i = 0.512 (0.373) (1) = 0.19oC BP = (100 + 0.19)oC = 100.19oC DTf = Kf m i = –1.86 (0.373) (1) = –0.69oC FP = (0 + –0.69)oC = –0.69oC 168 g cesium bromide are mixed w/2.50 kg H2O. Find BP and FP of mixture. For H2O, Kb = 0.512, Kf = –1.86. Cs1+ Br1– i=2 CsBr Cs1+ + Br1– 168 g m mol CsBr kg H2O 212.8 g 0.316 m 2.50 kg DTb = Kb m i = 0.512 (0.316) (2) = 0.32oC BP = (100 + 0.32)oC = 100.32oC DTf = Kf m i = –1.86 (0.316) (2) = –1.18oC FP = (0 + –1.18)oC = –1.18oC Molarity and Stoichiometry M= M mol L V M mol mol V mol = M L P ML ML P __ 1 Pb(NO3)2(aq) + __ 2 KI (aq) __ 1 PbI2(s) + __ 2 KNO3(aq) What volume of 4.0 M KI solution is required to yield 89 g PbI2? Stoichiometry for Reactions in Solution Step 1) Identify the species present in the combined solution, and determine what reaction occurs. Step 2) Write the balanced net ionic equation for the reaction. Step 3) Calculate the moles of reactants. Step 4) Determine which reactant is limiting. Step 5) Calculate the moles of product or products, as required. Step 6) Convert to grams or other units, as required. Stoichiometry steps for reactions in solution 1 Pb(NO3)2(aq) + 2 KI (aq) 1 PbI2(s) + 2 KNO3(aq) ? L 4.0 M 89 g What volume of 4.0 M KI solution is required to yield 89 g PbI2? Strategy: (1) Find mol KI needed to yield 89 g PbI2. (2) Based on (1), find volume of 4.0 M KI solution. X mol KI = 89 g PbI2 M= mol L L= 1 mol PbI2 2 mol KI 461 g PbI2 1 mol PbI2 = 0.39 mol KI mol 0.39 mol KI = 0.098 L of 4.0 M KI = M 4.0 M KI How many mL of a 0.500 M CuSO4 solution will react w/excess Al to produce 11.0 g Cu? Al3+ SO42– __CuSO4(aq) + __Al (s) __Cu(s) + __Al2(SO4)3(aq) 3 CuSO4(aq) + 2 Al (s) 3Cu(s) + 1Al2(SO4)3(aq) x mol 11 g X mol CuSO4 = 11 g Cu mol M = L 1 mol Cu 63.5 g Cu mol L = M 3 mol CuSO4 = 0.173 mol CuSO4 3 mol Cu 0.173 mol CuSO4 0.500 M CuSO4 0.346 L 1000 mL = 346 mL 1L = 0.346 L Stoichiometry Problems • How many grams of Cu are required to react with 1.5 L of 0.10M AgNO3? Cu + 2AgNO3 2Ag + ?g 1.5 L Cu(NO3)2 1.5L 0.10M .10 mol AgNO3 1 mol Cu 1L 2 mol AgNO3 63.55 g Cu = 4.8 g 1 mol Cu Cu Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Limiting Reactants • 79.1 g of zinc react with 0.90 L of 2.5M HCl. Identify the limiting and excess reactants. How many liters of hydrogen are formed at STP? Zn + 2HCl 79.1 g 0.90 L 2.5M ZnCl2 + H2 ?L Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Limiting Reactants Zn + 2HCl 79.1 g 0.90 L 2.5M 79.1 g Zn ZnCl2 + H2 ?L 1 mol Zn 1 mol H2 22.4 L H2 65.39 g Zn 1 mol Zn 1 mol H2 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem = 27.1 L H2 Limiting Reactants Zn + 2HCl 79.1 g 0.90 L 2.5M 0.90 L 2.5 mol HCl 1 mol H2 1L 2 mol HCl ZnCl2 + H2 ?L 22.4 L H2 = 25 L H2 1 mol H2 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Limiting Reactants Zn: 27.1 L H2 HCl: 25 L H2 Limiting reactant: HCl Excess reactant: Zn Product Formed: 25 L H2 left over zinc Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem A Hydrocarbon • Typical petroleum product • Non-polar CH2 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 C18H38 CH2 CH2 CH2 CH2 CH3 CH2 Oil and Water Don’t Mix • Oil is nonpolar • Water is polar “Like dissolves like” Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 470 Hydrogenation tub (soft) margarine + H2 heat, nickel catalyst vegetable oils Timberlake, Chemistry 7th Edition, page 570 shortening stick margarine Molecular Polarity -- e– are shared equally -- tend to be symmetric nonpolar molecules: e.g., fats and oils H H O polar molecules: -- e– NOT shared equally e.g., water “Like dissolves like.” polar + polar = solution nonpolar + nonpolar = solution polar + nonpolar = suspension (won’t mix evenly) H H–C–H H–C–H H–C–H H–C–H H Using Solubility Principles Chemicals used by body obey solubility principles. -- water-soluble vitamins: e.g., vit. C -- fat-soluble vitamins: e.g., vits. A, D Dry cleaning employs nonpolar liquids. -- polar liquids damage wool, silk -- also, dry clean for stubborn stains (ink, rust, grease) -- (tetra) perchloroethylene is in common use Cl Cl C=C Cl Cl Dry Cleaning UnitOne unit washes and dries Washing Process Drying Process Process used for Wash and dry Pressing Dirty Clothes Dirty Perc Filter Perc Warm Vapor From Dryer Condenser Used, Filtered Perc New Perchloroethylene Perc Storage/ Collection (PERC) Separator Condensed Liquid Perc Collected Used Perc Clean Perc Distiller Air to Atmosphere Finished Clothes Water Discharge Hazardous Waste* *Soil, dirt, unrecovered Perc emulsifying agent (emulsifier): -- molecules w/both a polar AND a nonpolar end -- allows polar and nonpolar substances to mix e.g., soap detergent lecithin MODEL OF A SOAP MOLECULE Na1+ POLAR HEAD NONPOLAR HYDROCARBON TAIL eggs Soap Making A 20-mule team hauling borax out of the valley. Photo provided by the National Park Service. Borax (Na2B4O7 _10H2O), the most widespread borate mineral was found to help remove dirt from people and cloth. Borax is crumbly and powdery, and dissolves easily in water. Borax became an alternative to the very harsh soap which was used prior to the discovery of borax in the late 1800's. This light and easy to use substance was hailed the world over as a washing, cleansing, antiseptic, preservative, and medicine miracle. In the 1880s, large borate deposits were discovered in Death Valley, California. However, the Death Valley borate deposits were located almost 170 miles from the nearest railway. In order to get the borate to the railway economically, the owners of the Death Valley mines used large wagons pulled by teams of 20 mules. The detergents made from this borate were thus sold as "20 Mule Team Borax". A 20 mule team hauling borax in Death Valley Saponification Process of making soap from animal fat or vegetable oil using a base. O CH2 – O – C – (CH2)14CH3 CH2 – OH O O CH – O – C – (CH2)14CH3 + 3 NaOH CH – OH + 3 Na+ -OC – (CH2)14CH3 O CH2 – O – C – (CH2)14CH3 glyceryl tripalmitate (tripalmitin) CH2 – OH sodium hydroxide glycerol 3 sodium palmitate (soap) A Phospholipid polar head nonpolar tails (a) chemical structure of a phospholipid polar head nonpolar tails (b) simplified way to draw a phospholipid Timberlake, Chemistry 7th Edition, page 576 A Model of a Cell Membrane Polar Nonpolar Cholesterol Timberlake, Chemistry 7th Edition, page 587 Proteins Phospholipid bilayer Formation of a Triglyceride Stearic Acid Fatty acid Carboxylic acid group Soap COO- bonds to a metal ion (Na+) Na+ H+ lost from Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 257 COOH Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Sodium stearate: a soap Sodium dodecyl sulfate: a detergent Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Cleaning Action of Soap Micelle Timberlake, Chemistry 7th Edition, page 573 Micelle Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. micelle Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. SOAP -- made from animal and vegetable fats vs. DETERGENT -- made from petroleum -- works better in hard water Hard water contains minerals w/ions like Ca2+, Mg2+, and Fe3+ that replace Na1+ at polar end of soap molecule. Soap is changed into an insoluble precipitate (i.e., soap scum). micelle: a liquid droplet covered w/soap or detergent molecules Solvation “Like Dissolves Like” NONPOLAR POLAR NONPOLAR POLAR Solvation Soap / Detergent • polar “head” with long nonpolar “tail” • dissolves nonpolar grease in polar water micelle Lava Lamp It is… H H O Polar mixture Water Polyethylene glycol H H Chlorinated paraffin Paraffin from kerosene H H H H H-O-C-C-O-C-C-O-C-C-O-C-C-O-H H H mixture theNonpolar moment H H H H H H H H Cl H H H H Cl H H H H H Cl H H H H Cl H H H H-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-H H H H Cl H H H H Cl H H H H H Cl H H H Cl H Heat transfer coil H H H H H H H H H H H H H H H H H H H H Bulb gives heat and light prehistoric here to stay H-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-H H H H H H H H H H H H H H H H H H H H H Dialysis A semi-permeable membrane allows small particles to pass through while blocking larger particles. Dialysis is used to clean blood when people suffer kidney failure. Solution, Suspension, Colloid Timberlake, Chemistry 7th Edition, page 309 Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. Solubility UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form increasing concentration Solubility vs. Temperature for Solids 140 KI 130 Solubility Table shows the dependence of solubility on temperature Solubility (grams of solute/100 g H2O) 120 NaNO3 110 gases solids 100 KNO3 90 80 HCl NH4Cl 70 60 NH3 KCl 50 40 30 NaCl KClO3 20 10 SO2 0 LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517 10 20 30 40 50 60 70 80 90 100 Solubility Solubility maximum grams of solute that will dissolve in 100 g of solvent at a given temperature varies with temperature based on a saturated solution Solubility Solids are more soluble at... • high temperatures. Gases are more soluble at... • low temperatures & • high pressures (Henry’s Law). • EX: nitrogen narcosis, the “bends,” soda Solubility how much solute dissolves in a given amt. of solvent at a given temp. SOLUBILITY CURVE KNO3 (s) KCl (s) Solubility (g/100 g H2O) HCl (g) Temp. (oC) unsaturated: saturated: supersaturated: above the line solution could hold more solute; below line solution has “just right” amt. of solute; on line solution has “too much” solute dissolved in it; Solids dissolved in liquids Sol. Gases dissolved in liquids Sol. To As To , solubility To As To , solubility Classify as unsaturated, saturated, or supersaturated. per 100 g H2O 80 g NaNO3 @ 30oC unsaturated 45 g KCl @ 60oC saturated 50 g NH3 @ 10oC unsaturated 70 g NH4Cl @ 70oC supersaturated Per 500 g H2O, 120 g KNO3 @ 40oC saturation point @ 40oC for 100 g H2O = 66 g KNO3 So sat. pt. @ 40oC for 500 g H2O = 5 x 66 g = 330 g 120 g < 330 g unsaturated Describe each situation below. (A) Per 100 g H2O, 100 g NaNO3 @ 50oC. Unsaturated; all solute dissolves; clear solution. (B) Cool solution (A) very slowly to 10oC. Supersaturated; extra solute remains in solution; still clear. (C) Quench solution (A) in an ice bath to 10oC. Saturated; extra solute (20 g) can’t remain in solution, becomes visible. Hotpack / Coldpack Solubility of Sodium Acetate Solubility(g/100 g H2O) 150 Saturated Supersaturated solution 100 Unsaturated solution 50 Video Clip 0 25 50 75 Temperature (oC) Charles H.Corwin, Introductory Chemistry 2005, page 378 100 The small crystal A single crystal ofcauses sodiumextensive acetate, crystallization, and eventually NaC2H3O2, is dropped into a supersatureated solution the solute forms a solid mass of NaC2H3O2. Vitamins • Multi Vitamin – Provides many essential vitamins – “Expensive urine” • Water Soluble – Vitamin C – Must be replenished regularly • Fat Soluble – Can overdose – Vitamin A – Can be ingested periodically, stored in body fat Gas, Liquid, and Solid Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441 Hydrogen Bonding • Intermolecular forces of attraction between molecules (hydrogen bonds) Intermolecular forces H O Bonds • Bonds exist within molecules (covalent bonds) Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 442 H O H H Bonds Interaction of Dipoles • (a) Interaction of two polar molecules. - + - + - + + - - • (b) interaction of many dipoles in a liquid + - + Attraction Repulsion Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 442 + - + - + + Polar Water Molecule d + H 2d - O H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 d+ Hydrogen Bonding among water Molecules Hydrogen Bonding among water Molecules Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 H 2 3 4 5 6 7 1 Li He Be B C N O F 2 Ne 3 4 Na Mg 5 Al 6 Si 7 P 8 S 9 Cl 10 Ar 13 14 15 16 Cu Zn Ga Ge As Se 17 Br 18 Kr 36 Xe 11 K 12 Ca Sc Ti V Cr Mn Fe Co Ni 19 20 Rb Sr 21 Y 22 23 24 25 26 27 28 29 30 31 32 33 34 Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 35 I 37 38 Cs Ba 39 40 Hf 55 Fr 87 56 Ra 88 * W 41 Ta 42 W 43 44 45 Re Os Ir 72 73 74 75 76 77 Rf Db Sg Bh Hs Mt 46 47 48 49 50 Pt Au Hg Tl Pb 51 52 Bi Po 53 54 At Rn 78 83 85 79 80 81 82 Hydrogen Bonding 84 86 H 2O H2Te 0 -100 -200 Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 Boiling Points of Covalent Hydrides 100 104 105 106 107 108 109 Boiling point (oC) 1 H 2S H2Se 2 3 4 Period of X (H2X) 5 Boiling Points of Covalent Hydrides H 2O Boiling point (oC) 100 0 H2Te -100 H 2S H2Se SnH4 GeH4 SiH4 -200 CH4 50 100 Molecular mass 150 Heating / Cooling Curve of Water Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 445 Water Molecules in Liquid and Steam Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 446 Microscopic view of a liquid near its surface Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 449 Behavior of a liquid in a closed container Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 450 Water rapidly boiling on a stove Formation of a bubble is opposed by the pressure of the atmosphere Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 452 Boiling Points of Covalent Hydrides H 2O Boiling point (oC) 100 H2Te 0 -100 -200 Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 H 2S H2Se 2 3 4 Period of X (H2X) 5 H 1 2 3 4 5 6 Be B C N O F 2 Ne 3 4 Na Mg 5 Al 6 Si 7 P 8 S 9 Cl 10 Ar 13 14 15 16 Cu Zn Ga Ge As Se 17 Br 18 Kr 36 Xe 11 K 12 Ca Sc Ti V Cr Mn Fe Co Ni 19 20 Rb Sr 21 Y 22 23 24 25 26 27 28 29 30 31 32 33 34 Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 35 I 37 38 Cs Ba 39 40 Hf 55 Fr 87 56 Ra 88 * W 41 Ta 42 W 43 44 45 Re Os Ir 72 73 74 75 76 77 Rf Db Sg Bh Hs Mt 46 47 48 49 50 Pt Au Hg Tl Pb 51 52 Bi Po 53 54 At Rn 78 83 85 79 80 81 82 84 86 H 2O H2Te 0 -100 -200 Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 Boiling Points of Covalent Hydrides 100 104 105 106 107 108 109 Boiling point (oC) 7 1 Li He H 2S H2Se 2 3 4 Period of X (H2X) 5 H 2 3 4 5 6 7 1 Li He Be B C N O F 2 Ne 3 4 Na Mg 5 Al 6 Si 7 P 8 S 9 Cl 10 Ar 13 14 15 16 Cu Zn Ga Ge As Se 17 Br 18 Kr 36 Xe 11 K 12 Ca Sc Ti V Cr Mn Fe Co Ni 19 20 Rb Sr 21 Y 22 23 24 25 26 27 28 29 30 31 32 33 34 Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 35 I 37 38 Cs Ba 39 40 Hf 55 Fr 87 56 Ra 88 * W 41 Ta 42 W 43 44 45 Re Os Ir 72 73 74 75 76 77 Rf Db Sg Bh Hs Mt 46 47 48 49 50 Pt Au Hg Tl Pb 51 52 Bi Po 53 54 At Rn 78 83 85 79 80 81 82 Hydrogen Bonding 84 86 H 2O H2Te 0 -100 -200 Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 443 Boiling Points of Covalent Hydrides 100 104 105 106 107 108 109 Boiling point (oC) 1 H 2S H2Se 2 3 4 Period of X (H2X) 5 Boiling Points of Covalent Hydrides H 2O Boiling point (oC) 100 0 H2Te -100 H 2S H2Se SnH4 GeH4 SiH4 -200 CH4 50 100 Molecular mass 150 Group16 Hydrogen Compounds Compound Molar Mass Melting Point (oC) Boiling Point (oC) H fusion (cal/mol) H vapor (cal/mol) H2O 18 0.0 100.0 1440 9720 H2S 34 -85.5 -60.7 568 4450 H2Se 81 -60.4 -41.5 899 4620 H2Te 130 -48.9 -2.2 1670 5570 Ethanol is Polar dH d+ O H Polar bond H C H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 469 C H H Ethanol and Water are Soluble H H H H C O O H C H ‘Like dissolves like’ H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 469 H Molecular Structure of Ice Hydrogen bonding Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 455 Sodium Chloride Crystal = Cl- = Na+ Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 455 Packing of NaCl Ions = Cl1Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 456 = Na1+ Packing of NaCl Ions Electron Microscope Photograph of NaCl Dissolving of Salt in Water Na+ ions Water molecules Clions NaCl(s) + H2O Na+(aq) + Cl-(aq) Dissolving of NaCl H H O Na+ + + + + + - - hydrated ions - Cl- Timberlake, Chemistry 7th Edition, page 287 + - An alloy is a homogeneous mixture of metals. • Brass = Copper + Zinc • Solid brass • homogeneous mixture Copper Zinc Solid Brass • Brass = Copper + Zinc • Brass plated • heterogeneous mixture • Only brass on outside Copper Zinc Brass Plated Hardened Steel Steel Iron Carbon Gold Gold Copper Silver 24 karat gold 24/ 24 atoms Au 18 karat gold 18/ 24 atoms Au 14 karat gold 14/ 24 atoms Au Precipitation Reaction Between AgNO3 and KCl AgCl AgNO3(aq) + KCl(aq) Ag+ + NO3- + K+ + Cl- Ag+ K+ Cl- NO3- + NO3- Ag Ag+ ? ClK+ Cl- ClK+ NO3- in silver nitrate solution unknown white solid unknown white solid in potassium chloride solution Ag+ + NO3- + K+ + Cl- Ag+ + Cl- + K+ + NO3product Ag+ AgNO3(aq) + KCl(aq) product AgCl(s) + KNO3(aq) AgCl precipitate AgNO3(aq) + KCl(aq) KNO3 (aq) + AgCl(s) Formation of a solid AgCl AgNO3(aq) + KCl(aq) KNO3 (aq) + AgCl(s) Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 220 Clogged Pipes – Hard Water Step 1: Acid rain is formed H2O + CO2 H2CO3 carbonic acid Step 2: Acid rain dissolves limestone H2CO3 + CaCO3 Ca(HCO3)2 H2CO3 + MgCO3 Mg(HCO3)2 limestone ‘hard’ water Water softener Pipes develop Scales Step 3: Hard water is heated and deposits scales Ca(HCO3)2 D CaCO3(s) + H2O + CO2 scales on pipes Mg(HCO3)2 D MgCO3(s) + H2O + CO2 1 gram = 1/7000th pound 300 gallons / day with 10 grain water supply No More Hard Water Scale No More Ugly Hard Water Spotting Protects Plumbing and Appliances Saves Money on Cleaning Products Water Purification Cation Exchanger Hard Water H+ OH- H+ (b) Fe3+ OH- Deionized Water OH- H+ (a) Ca2+ H+ Mg2+ Na+ Anion Exchanger H+ OH- H+ OH- (c) OH- H+ OH- H+ OH- Hard water is softened by exchanging Na+ for Ca2+, Mg2+, and Fe3+. Corwin, Introductory Chemistry 2005, page 361 (a) (b) (c) The cations in hard water are exchanged for H+. The anions in hard water are exchanged for OH-. The H+ and OH- combine to give H2O. Which ions are removed from hard water to produce soft water? Na+(aq) + H (resin) Cl-(aq) + (resin) OH Na (resin) (resin) Cl + + H+(aq) OH-(aq) Notice that the ion exchange resin produces both hydrogen ions and hydroxide ions which can readily combine to give water. H+(aq) + OH- (aq) H2O (aq) The net result is that the resin removes all ions from water passing through the deionizing system. Hard water is softened by exchanging Na+ for Ca2+, Mg2+, and Fe3+. Corwin, Introductory Chemistry 2005, page 361 Calcium (Ca2+) and Magnesium (Mg2+) Ions in Untreated Water Sodium (Na1+) Ions on beads Calcium (Ca2+) and Magnesium (Mg2+) Ions on beads Sodium (Na1+) Ions in Treated Water Reverse Osmosis semipermeable membrane fresh water pressure salt water Pressure here Reverse Osmosis Water Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 267 Solution Semipermeable membrane Osmotic pressure Pure solvent Applied pressure needed to prevent volume increase Solution Net movement of solvent Semipermeable membrane Solute molecules Solvent molecules The pressure required to allow for no transport of solvent across the membrane is called the OSMOTIC pressure and obeys the relation: solute n R T MR T Vsolute Osmotic pressure has a great effect on living CELLS, because their walls are a semipermeable membrane. Net Solvent Flow semipermeable membrane Dilute solution Solute particle Ralph A. Burns, Fundamentals of Chemistry 1999, page 430 Net flow Solvent particle of solvent Concentrated solution Dissociate in Water DUE DATES ARE CLOSER THAN THEY APPEAR Meth Video Chemistry of B&W Photography Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. 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