UB CHE 102LEC - Chapter-13-Outline (29 pages)

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Chapter-13-Outline



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Chapter-13-Outline

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Pages:
29
School:
University at Buffalo-SUNY
Course:
Che 102lec - General Chemistry Lecture
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CHE 102 Lecture Outline Chapter 13 Syllabus Info Please read entire syllabus located on UB Learns Lecture UB Learns Lecture Material Announcements made at start of lecture Recording Posted in Class Recording link Skeleton Outlines to help take notes if you wish Answers to Additional Problems extra problems are located at end of each outline Additional Videos YouTube videos I have found pertaining to the more difficult material Please bring to EVERY class Outlines UB Learns Calculator Periodic table Equation pg UB Learns Mastering chemistry Technical Issues Contact Mastering Chemistry Pop up Blocker disabled OR Flash player updated 6 attempts at each submit button Hints Some questions have them If answer correctly earns extra pts but if answer incorrectly can lose points But if help you answer overall question then you usually earn more points than you would lose if you didn t answer the question No points lost if look at them HIGHLY recommend using when available Suggestions Each assignment 1 3 hrs Work the problems pertaining to material learned in that day s lecture If can t answer in 10 minutes or 3 4 tries Move on and seek help Getting Help Go to Instructor office hrs Starts 8 28 17 See pg 1 of syllabus First 2 weeks of classes ALL Dr Gulde s office hrs are in NSC325 Go to NSC110 for TA help Starts Mon 9 11 17 1st come 1st serve basis 1 CHE 102 Lecture Outline Chapter 13 Chapter 13 Properties of Solutions Solutions Solutions are homogeneous uniform mixtures Solute usually present in smaller amounts it s dissolving Solvent usually present in larger amounts causes dissolving We are familiar w water but doesn t have to be Solution Equilibrium Dissolution dissolves solute breaks apart into ions or molecules Crystallize when dissolved solute comes out of soln forms a solid Solution Equilibrium when the rates of these processes are equal dissolves crystalize Types of Solutions 2 CHE 102 1 Lecture Outline Chapter 13 Saturated solutions contains max amount of solute for a solvent at a specific temp Sugar 25 C 211g 100g H2O 50 C 260g 100g H2O If add more solute it won t dissolve Solubility amount of solute needed to form a saturated solution 2 Unsaturated solutions contains less than max amount of solute at a specific temp If add more solute it will dissolve until reach saturation 3 Supersaturated solutions contains more than the max amount of solute at a specific temp To make heat saturated solution add solute then cool to original temp Not stable If add more solute excess crystallizes until saturation reached Alum exp From CHE101 3 CHE 102 Lecture Outline Chapter 13 WHY do Solutions form 1 Entropy S an increase in disorder randomness 2 Similar forces dissolve within each other Like dissolves like Polar solvents dissolve polar or ionic solutes Nonpolar solvents dissolve nonpolar solutes Liquid solubility terminology Miscible mixes completely Immiscible doesn t mix significantly Ex Oil Water no solution b c forces not similar 4 CHE 102 Lecture Outline Chapter 13 Type of Forces A Intramolecular forces is b t atoms within a molecule aka BONDS Solid lines Chap 8 Ionic Covalent Metallic B Intermolecular forces IMF is b t atoms of separate molecules dashed lines Chap 11 London dispersion Dipole Dipole H bonding Ion dipole Intramolecular force Intermolecular force Intermolecular Forces IMF 1 London Dispersion the movement of electrons in the electron cloud creating an instantaneous dipole temporary partial charge All molecules have these 2 Dipole Dipole attraction between neutral polar molecules Permanent dipole 5 CHE 102 Lecture Outline Chapter 13 3 Hydrogen bonding Extra strong Dipole Dipole force Required a H atom bonded to N O or F b Attracted to lone pair of another N O or F atom Ion dipole between ions partial charges dipoles of polar molecules Exist when ionic compounds ex NaCl dissolve in polar substance ex water Sample Problems 1 List all the intermolecular forces associated with a CH3Cl Dispersion Yes Dipole dipole Yes H bonding No Ion dipole No b H2O Dispersion Yes Dipole dipole Yes H bonding Yes Ion dipole No 2 Will a solution of CH3Cl and H2O form are they miscible Yes Like Dissolves Like CH3Cl Polar H2O Polar 6 CHE 102 Lecture Outline Chapter 13 HOW do Solutions form Forces bonds are broken new forces created Solvation when solute ions or molecules is surrounded by solvent in a specific way Hydration special case of solvation b c water solvent NaCl s in water Water Water to Nacl NaCl apart There are 3 interactions involved in solution formation each has an enthalpy H change Ex NaCl s Na aq Cl aq A Solute Solute interaction Hsolute must be broken Requires energy endothermic B Solvent Solvent interaction Hsolvent must be broken Requires energy endothermic C Solute Solvent interaction Hmix must be formed Gives off energy exothermic All 3 processes occur at the same time 7 CHE 102 Lecture Outline Chapter 13 OVERALL enthalpy of Solution Hsoln add all 3 processes Hsoln can be endothermic or exothermic Depends on size of IMF Soln formation is favored when Hsoln is exothermic Solute Solvent particles are highly attracted to each other they want to be together so Hmix is large Why does this disfavored endothermic solution form NH4NO3 HSoln 26kJ Entropy S disorder counteracts small HSoln value If Hsoln is very positive no soln forms 8 CHE 102 Lecture Outline Chapter 13 Solution Formation Review Solute Solvent Interactions 1 Enthalpy Hsoln heat Solutions usually form when Hsoln 0 exo Strong solvent solute interactions 2 Entropy S disorder Solutions usually form when S increases i Helps compensate for Hsoln 0 endo Sample Problems 1 What forces are associated with each process involved when CH3Cl dissolves in water Solute Diploe Dipole CH3Cl Solvent H2O H bonding Dipole Dipole Question 13 2 Label the following processes as exothermic or endothermic a Breaking solvent solvent interactions to form separated particles b Forming solvent solute interactions from separated particles A B C D a Endothermic Endothermic Exothermic Exothermic b Endothermic Exothermic Endothermic Exothermic 9 CHE 102 Lecture Outline Chapter 13 Factors Affecting Solubility of solutes in water 1 Structural Factors Like Dissolves Like a Polarity Solute solubility increases as of polar groups increases b c more attraction sites Sucrose dissolved better 5 8 b Liquids Solute solubility decreases as carbon chain length increases b c solute becomes more non polar Hexanol Ethanol are both polar but hexanol is less c Gases


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