1MixturesChapter 16Pure Substance• A material consisting of only one type of element or compoundMixture• A collection of two or more pure substance that can be separated by physical means– Homogeneous: all samples of the mixture have the same ratio of components– Heterogeneous: different components can be seen as individual substances • Most materials are mixturesMixtures Homogeneous Mixtures• Composition is the same throughout• Solution: all components are in the same phase (which may be any phase)• Suspension: there are different phases presentSolutionsA homogeneous mixture consisting of ions or molecules• Solvent—the major component• Solute—the minor components• ‘Saturated’—no more solute will dissolve in the solventConcentration of Solution• The amount of solute in solution• Measured in – Grams per liter– Parts per million ppm– # of molecules per liter MConcentration =SoluteSolutionParts per million• Milligrams of solute per liter of solution1 ppm =1 part solute1,000,000 parts solution1 milligram solute1 liter solution=Number of Molecules• 602 billion trillion• 602,000,000,000,000,000,000,000• 6.02 x 1023• A ‘mole’ of molecules2Mole of atoms• 6.02 x 1023• Atomic mass is number of grams of a mole of atoms• Or molecular mass of a molecule is number of grams of moleculesFormula Mass• Mass of a mole of atoms or moleculesCarbon, C 12Oxygen, O232Carbon dioxide, CO244Sucrose, C12H22O11342Molarity• Moles of solute per liter of solution• 1 M sucrose solutionSolubility• Ability of solute to dissolve in a solvent• Often temperature dependentOxygen solubilityOxygen Solubility0.0060.0080.010.0120.0140.0160 10203040Temperature (degrees C)g oxygen/L waterSolubility factors• Temperature of substances• Types of molecules– Polar molecules are soluble in polar solvents– Nonpolar molecules are soluble in nonpolarsolvents• Acidity of solvent, especially for polar moleculesInsoluble• Does not dissolve to any appreciable extent in the solvent• Salt is insoluble in oil• Salt is soluble in waterPrecipitate• Solute that comes out of solution• Often caused by change in temperatureSoap• Non-polar and polar properties• Polar part attracts water—CH chain• Non-polar part attracts ‘grime’—NaCO23Soap and grime Detergent• Stronger grease penetration• Lower cost of production• Sulfate or sulfonate group attached to CH chainHard Water• Contains Mg and/or Ca ionic compounds• Less soluble than Na ionic compounds• Leave scale in pipes and on surfacesCleaning in Hard Water • Ions of Ca2+or Mg2+ions bond to the polar end of the cleansing compound and reduce the quantity available for cleaning• Detergent mixtures often contain Na2CO3to bond with the Ca2+and Mg2+ionsHome water softeners• Ion exchange resin• Charge with salt NaCl to have Na+ions available to treat hard water• Water ions attracted to resin, and exchange the Na+ions for its Ca2+or Mg2+ionsIon-Exchange resinPurifying the Water We Drink• The first step to purifying water is removing particles and bacteria.• Water is then aerated to improve the taste and smell.• Lastly, the water is disinfected with chlorine gas (or ozone).Purifying the Water We Drink• Sea water can be converted to drinking water through desalination.– Distillation– Reverse osmosisPurifying the Water We Drink4Distillation Osmosis Reverse OsmosisWastewater Treatment• Screening removes large insoluble items.• Primary treatment allows smaller insolubles to settle to the bottom or rise to the top for removal.• Secondary treatment aerates the water and allows finer particles to settle for removal.• Tertiary treatment filters the water.Primary Wastewater TreatmentSecondary Wastewater
View Full Document
Unlocking...