1Week 3 CHEM 1310 - Sections L and M 1Wed | Sep 5, 2007 Chapter 4: Types of Chemical Reactions– 4.1 Water– 4.2 Electrolytes– 4.3 Composition of Solutions Exam #1 - Next Friday (Sep 14)Week 3 CHEM 1310 - Sections L and M 2Characteristics of Water• Composition: H2O• Bent shape• Covalent -OH bonds• Polar (unequal chargedistribution)2Week 3 CHEM 1310 - Sections L and M 3Why is Water Bent?Oxygen has 2 lone pairs of electrons. To avoid steric hindrance,the -OH bonds spread toa 105º angle.More on shapes of molecules later… Week 3 CHEM 1310 - Sections L and M 4DissolutionPolar water molecules aid in dissolving ions of a salt.Text Fig. 4.2Hydration3Week 3 CHEM 1310 - Sections L and M 5When a solid or liquid enters into an aqueous phaseNH4NO3(s) → NH4+(aq) + NO3- (aq)AmmoniumNitrate(solid)AmmoniumCation(in solution)NitrateAnion(in solution)What is Dissolution?H2O(l)Week 3 CHEM 1310 - Sections L and M 6“Like Dissolves Like”Ethanol Water interacting with ethanolSubstances with similar intermolecular attractiveforces tend to be soluble in one another.4Week 3 CHEM 1310 - Sections L and M 7Polar Water & DissolutionThriftyfun.comWater will not dissolve nonpolar substances.NONPOLAR HydrocarbonsFatsOilsGreaseGasolineDry Cleaning Solventsetc.Week 3 CHEM 1310 - Sections L and M 8Polar Water & DissolutionWater will not dissolve nonpolar substances.NONPOLAR HydrocarbonsFatsOilsGreaseGasolineDry Cleaning Solventsetc.5Week 3 CHEM 1310 - Sections L and M 9SolubilityThe largest amount of a substance that can dissolvein a specific amount of solvent at RT Soluble• > 1 gram of solute per 100 g water Slightly Soluble• 0.01 - 1 gram of solute per 100 g water Insoluble• < 0.01 gram of solute per 100 g waterWeek 3 CHEM 1310 - Sections L and M 10Solubility Concepts1. Pairs of liquids that mix in any proportion aretermed miscible.2. Liquids that do not mix are termed immiscible.3. Substances with similar intermolecularattractive forces tend to be soluble in oneanother.6Week 3 CHEM 1310 - Sections L and M 11CharacteristicsElectrolytes vs. Non-electrolytesStrong vs. Weak ElectrolytesElectrolytesSubstances that dissolve in H2O to give solutions thatconduct electricity better than H2O alone doesSucroseAcetic AcidHydrochloric AcidStrongWeak Non-ElectrolyteWeek 3 CHEM 1310 - Sections L and M 12ElectrolytesSubstances that dissolve in H2O to give solutions thatconduct electricity better than H2O alone doesK2SO42K+ + SO42-Ionization7Week 3 CHEM 1310 - Sections L and M 13Strong Electrolytes Soluble Salts– Dissolve completely into cations and anions– Examples: NaCl, KCl, and NH4Cl Strong Acids– Dissolve in water to make H+– Examples: HCl, HNO3, and H2SO4 Strong Bases– Dissolve in water to make OH-– NaOH and KOHWeek 3 CHEM 1310 - Sections L and M 14Weak Electrolytes Produce few ions when dissolved in water Weak Acid: Acetic Acid Weak Base: Ammonia8Week 3 CHEM 1310 - Sections L and M 15Weak ElectrolytesPRS QuestionWhat ion(s) will be formed from dissolution ofacetic acid, HC2H3O2, in water?1. OH-2. H+3. H3+4. H+ and OH-Week 3 CHEM 1310 - Sections L and M 16PRS Q1 AnswerWhat ion(s) will be formed from dissolution ofacetic acid, HC2H3O2, in water?Acetic AcidHC2H3O2 H+ + C2H3O2- Acetate Anion1. OH-2. H+3. H3+4. H+ and OH-Correct AnswerYou know H+ will form sincethe solute here is an acid.9Week 3 CHEM 1310 - Sections L and M 17Weak Electrolytes Produce few ions when dissolved in water Weak Acid: Acetic Acid Weak Base: AmmoniaWeek 3 CHEM 1310 - Sections L and M 18Weak ElectrolytesPRS QuestionWhat ion(s) will be formed from dissolution ofammonia, NH3, in water?1. OH-2. NH4+3. 1 and 24. None of these10Week 3 CHEM 1310 - Sections L and M 19PRS Q2 AnswerWhat ion(s) will be formed from dissolution ofammonia, NH3, in water?1. OH-2. NH4+3. 1 and 24. None of theseNH3 + H2O NH4+ + OH- Note: Choice #2 was a typo! It was supposed to be NH4+.Then Choice #3 would be the correct answer as stated in the lecture period. Week 3 CHEM 1310 - Sections L and M 20Molarity & DilutionsM = molarity = mol L-1molessoluteliterssolutionconcentrationsolute =amountsoluteVolumesolutionM1 x V1 = M2 x V211Week 3 CHEM 1310 - Sections L and M 21CalculationsM1 x V1 = M2 x V2What volume of blood contains 1.0 mg of NaClif typical blood serum is 0.14 M NaCl?M = molarity = mol L-1FW of NaCl = 58.45 g/molSee Example 4.3 in the textWeek 3 CHEM 1310 - Sections L and M 22Next Friday Types of Chemical Reactions– Precipitation Reactions– Acid-Base Reactions– Oxidation-Reduction (“Redox”) Reactions Reminder: Exam #1 - Friday, Sep 14Attendance is