Updated Oct.14/04 ----------------------------------------------------------------------------------------- NUMERICAL ANSWERS TO ASSIGNED TUTORIAL PROBLEM SETS FOR CHEM206 FROM KOTZ & TREICHEL'S CHEMISTRY & CHEMICAL REACTIVITY ----------------------------------------------------------------------------------------- NOTE: these answers have NOT been verified, EXCEPT #91 HAS BEEN CORRECTED NOW. NOTE: "^" means "raised to the power of..." to indicate scientific notation Ch. Q# Ans. Units SFs Comments --------------------------------------------------------------------------------------------------- 14 6 higher [solvent] inside cucumber; water flows out 14 12a ionic solid --> soluble in water 14 12b polar --> soluble in water 14 12c nonpolar --> soluble in benzene 14 12d ionic solid --> soluble in water 14 12e nonpolar --> soluble in benzene 14 17 0.696 M 3 molarity 14 17 0.886 mol/kg 3 molality 14 17 0.0392 3 mole fraction camphor 14 17 11.9 % 3 weight percentage 14 21 2.18 g 3 mass to add 14 21 9.22x10^-4 3 mole fraction sodium nitrate 14 27a 2.6x10^-7 mol/kg 2 Ag+ ion molality 14 27b 3.6x10^6 L 2 volume of water to treat to get 100 g Ag 14 29 acetone is polar…strong dipole-dipole interactions with water… 14 33 Li2SO4: as T increases, more solid will ppt out 14 33 LiCl: as T increases, more solid will dissolve 14 35 Mg2+ most strongly hydrated (small; high charge) 14 35 Cs+ least strongly hydrated (large; lower charge) 14 37 8.80x10^-7 M/mmHg 3 gas solubility decreases as T increases, so choose value < constant's value at 25C 14 41 17.6 mm Hg 3 vapour pressure 14 47 80.20 C 4 bp of 0.0407 molal solution of caffeine in benzene 14 49 0.13 2 mole fraction glycerol 14 51 2500 g 2 mass ethylene glycol added 14 55 180 g/mol 2 for 0.14 molal solution of BHA 14 57 C14H10 14 63 510 g 2 NaCl required to freeze at -10C NOTE: these answers ignore the 90% dissociation! 14 65a 0.20 mol/kg 2 particles in eth.glycol soln 14 65b 0.36 mol/kg 2 particles in K2SO4 soln 14 65c 0.30 mol/kg 2 particles in MgCl2 soln 14 65d 0.24 mol/kg 2 particles in KBr soln 14 65 soln m.p.: eth.glycol > KBr > MgCl2 > K2SO4 (lowest) 14 67 7.7 atm 2 for 0.30 M solution 14 73a Na2SO4 soln higher bp (higher [particles]) 14 73b Na2SO4 soln higher vapour P (lower [particles]) 14 75a 13.5 wt % 3 mass percentage NaCl 14 75b 0.0459 3 mole fraction NaCl 14 75c 2.67 mol/kg 3 molality NaCl 14 77a 0.162 3 mole fraction NaOH 14 77b 30.0 wt % 3 mass percent NaOH 14 77c 9.97 M 3 molarity NaOH 14 79 0.016 mol/kg 2 molality Ca(NO3)2 14 79 0.049 mol/kg 2 molality ions 14 81a Na2SO4 soln highest b.p. 14 81b Na2SO4 soln lowest m.p. 14 81c eth.glycol soln highest vapour pressure 14 87 888 g 3 precipitates out 14 91 50000 ppm 1 need total volume of solution (requires density) 14 93 104.13 C 5 for 8.06 molal solution 14 95 consider fraction of molecule that interacts favourably 14 99 55.3 M 3 molarity 14 99 55.5 mol/kg 3 molality 14 105a 0.0402 M 3 3SF because of conversion of T to Kelvin 14 105b 1.4 wt % 2 should have 2SF since limited by density data 14 107 77 g/mol 2 halide ion is likely Br- 14 109 292.4 g/mol 4 empirical FW…so formula = C18H24Cr