Lecture 28 Solutions 2 Read HW BLB 4 1 4 5 13 4 BLB 4 3 15 37 61 72 73 13 39 47 Sup 4 1 3 13 8 11 Know solutions concentrations Need help Get help TAs in CRC 211 Whitmore and SI hours on Chem 110 website my office hours Mon 12 30 2 Tues 10 30 12 in 324 Chem Bldg or 326 Chem Bonus deadline for BST 8 Intermolecular forces March 26 Bonus deadline for BST 9 Solutions dilutions April 2 Check out the grade u lator http courses chem psu edu chem110 spring grade htm Exam 3 Monday April 6 6 30 pm Sign up for the conflict exam if needed Last day to sign up is Wed April 1 Late drop deadline Friday April 10 11 59 pm via elion Sheets Page 1 Lecture 28 Expressing concentration weight mass of component 100 total mass ppm ppb Xa mole fraction moles of component total moles M molarity moles of solute liters of solution m molality moles of solute mass kg of solvent pH log H Sheets Page 2 Lecture 28 Example A solution containing equal masses of glycerol C3H8O3 and water has a density of 1 10 g mL Calculate A the weight percent of glycerol B the molality of glycerol C the mole fraction of glycerol and D the molarity of glycerol in the solution Sheets Page 3 Lecture 28 Example What is the final concentration of Na if 40 0 mL of 0 13 M sodium chloride is mixed with 40 0 mL of 0 13 M sodium carbonate Sheets Page 4 Lecture 28 Example Concentrated nitric acid is 71 by mass a What is the molarity of this solution b What is the mole fraction of nitric acid in this solution The density is 1 42 g mL Sheets Page 5 Lecture 28 Electrolytes a substance that yields ions when dissolved in water solution will conduct electricity strong electrolytes ionic or molecular compounds that ionize in solution NaCl s H2O Na aq Cl aq H2O HCl aq H2O H3O aq Cl aq weak electrolytes molecular compounds that are ionized in solution in equilibrium more later on in semester NH3 aq H2O NH4 aq OH aq CH3COO aq H3O aq CH3COOH aq H2O nonelectrolytes molecular compounds that do ionize in solution C6H12O6 s H2O C6H12O6 aq H2O glucose Sheets Page 6 Lecture 28 Flowchart for identifying electrolytes note ionic compounds are strong electrolytes but they could be insoluble memorize strong acids bases BLB Table 4 2 If a compound is an acid or a base but NOT one of the strong acids or bases then it MUST be a weak electrolyte Common misconception electrolytes are ionic compounds this is NOT TRUE e g HCl Sheets Page 7 Lecture 28 Memorize these strong acids bases Sheets Page 8 Lecture 28 Electrolytes con t strong or weak electrolytes are NOT determined by how much of a compound goes into solution rather strong or weak electrolytes ARE determined by what the compound does once it is in solution examples CH3COOH very soluble in water but weak electrolyte partially ionizes Ba OH 2 very slightly soluble in water but strong electrolyte completely ionizes once it gets into solution Sheets Page 9 Lecture 28 Examples of water soluble compounds Are these strong weak or non electrolytes in aqueous solution HCl NaCl CH3OH CH3COOH acetic acid NH3 Fe NO3 2 CuSO4 Ca OH 2 Sheets Page 10 Lecture 28 Examples What species are present upon dissolving each of the following substances in water MgI2 HOCH2CH2OH Al NO3 3 NH4Cl The correct formula for ammonium carbonate is A B C D E Sheets NH4 2CO3 NH4CO2 NH3 2CO4 NH4CO3 N2 CO3 3 Page 11 Lecture 28 Before next class Read HW BLB 4 1 4 5 13 4 BLB 4 3 15 37 61 72 73 13 39 47 Sup 4 1 3 13 8 11 Know electrolytes solutions Answers p 3 A 50 0 weight B 10 9 m C XC3H8O3 0 164 D 5 98 M p 4 0 195 M p 5 a 16 0 M b 0 412 p 11 bottom A Sheets Page 12 Lecture 28
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