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1、An Investigation of the Chemistry of WaterLESSON OUTLINElAudience: any student learning the general properties and chemistry of water (useful in earth science, biology, and chemistry)lIt assumes students have a basic understanding of general chemical terms (bond angle, bond length, H-bonding). lInte
2、nded for students to work individually to review the important properties of water- and further, their importance in every day life. lInteractive: Students can go directly to the section theyre interested in for quick information.lCould be used to review basic chemical and physical properties: phase
3、s of matter, bonding, solubility with water as the example molecule.SOLslThe following SOLs apply to this lesson: (I only picked ones from chemistry, though there are more in other areas that also apply)lChemistry: CH.2 The student will investigate and understand how conservation of energy and matte
4、r is expressed in chemical formulas and balanced equations. Key concepts include nomenclature; writing chemical formulas - molecular, structural, empirical, bonding types - ionic, covalentlCH.5 The student will investigate and understand that the phases of matter are explained by kinetic theory and
5、forces of attraction between particles. Key concepts include temperature, phase changes;molar heats of fusion and vaporization; specific heat capacity; solutions; and colligative properties.lCH.6 The student will investigate and understand how basic chemical principles relate to other areas of chemi
6、stry. Key concepts include organic and biochemistry;environmental chemistry.Physical PropertiesChemical PropertiesFast FactsImportance to the EnvironmentImportance to LifeINVESTIGATE WATERProperties of Liquid WaterlTetrahedral geometry: preferred locallyl2.3 H-bonds per liquid water moleculelDielect
7、ric constant at 25C: 78.5lHigh surface tensionBACKThe movie above shows the motion of water molecules at 25CFast Factsl 70% of the Earths surface is waterlWe consume 150 gallons of water per person per daylIn nature, water rarely exists as pure H2Ol“Water” is otherwise known as dihydrogen oxide, and
8、 hydrogen oxideBACKMolecular Formula: H2OMolecular Weight: 18.0152Molecular Geometry: bentH-O-H Bond Angle (lowest energy conformation): 104.3H-O Bond Length: 0.095nmVan der Waals radius: 0.14nmBACKBACKWater can act as a Bronsted- Lowry Acid or BaseThis reaction is governed by the equilibrium consta
9、nt:MORE CHEMICAL PROPERTIESThe pH of pure water is 7ACIDITYThe bent structure of water makes it POLARWater acts as a solvent for polar and ionic molecules (to learn more about how this works, click HERE)BACKProperties of Solid Water lCrystal Structure: “normal ice” contains a circuit of 6 water mole
10、cules H-bonded togetherlForms 4 H-bonds per water moleculelH-bond lifetime - about 10 microsecondsBACKMORE PROPERTIESProperties of Solid Water Freezing Point: 0C, 273K, 32FDensity: less than liquid water (due to H-bonding in crystal structure)BACKProperties of Gaseous WaterlBoiling Point: 100C, 373K
11、, 212FlWater vapor is the most important “greenhouse gas”lHigh Heat of VaporizationBACKBACKlWater is important in each of the Earths reservoirslBiosphere: living creatureslHydrosphere: all of the Earths waterlAtmosphere: gases including water vaporlLithosphere: rock cycle; formation of igneous, meta
12、morphic, and sedimentary rocksMORE ENVIRONMENTAL IMPORTANCEl1972: Clean Water Act passed CongresslResponse to: public concern for serious and widespread water pollution. lCWA: Primary federal law that protects our nations waters, including lakes, rivers, aquifers and coastal areas. BACKHYDROGEN BOND
13、INGBACKHYDROPHOBIC INTERACTIONSSOLVENT PROPERTIESMORE BIOLOGICAL IMPORTANCElForm through dipole-dipole interactions between moleculeslOxygen of water can “bond” with Hydrogen of another water moleculeBACKHYDROGEN BONDINGSOLVENT PROPERTIESBACKSOLVENTPROPERTIESHYDROPHOBIC INTERACTIONSIons are always h
14、ydrated in water and carry around a hydration shell“Water forms H-bonds with polar solutesHydrophobic interactions are extremely important in biochemistry!Hydration shells: molecules in solution orient so opposite charges are next to each other. For example: the H of water will orient itself toward
15、the Cl- of NaCl BACKHYDROPHOBICINTERACTIONSInteraction between water and nonpolar solutesNonpolar solutes “organize waterThe H-bond network of water reorganizes to accommodate the nonpolar soluteThis is an increase in order of water; decrease in entropyIMPORTANT IN METABOLIC PATHWAYSTHAT PRODUCE ENERGY FOR LIFEBACK
