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Unformatted text preview: Hints on Solving CHM 2046 Exam 3, Fall, 2007. (This is keyed to Form Code A.) (numerical answer follows Q. no.) 1. (3) Couple the -rxns which give: Al(OH 2 ) 3 (OH) 3 (s) + 3 H 2 O(l) Al(OH 2 ) 6 3+ (aq) + 3 HO ! (aq) for which E o = ! 0.65 V. Then apply Nernst eqn with E = 0 since system is at EQ. 2. (4) Write LSs! (Many missed this thus indicating that much LS practice is needed!) 3. (3) Of the cations for answer choices Ba 2+ & Li + are the weakest polarizers, and O 2 ! is far more difficult to polarize than I ! . 4. (3) Of the cations for answer choices only Sr 2+ is NGS. 5. (4) Of the metals for answer choices which are on the Info Sheet (Zn & Cu), E o data shows that Cu does not reduce H 3 O + (aq). So, by default, Mn, Sr, & La cannot be correct. 6. (5) For Mg, I.E. (3) tears into [Ne] core. Very costly! 7. (5) This should not require explanation yet this was a commonly missed Q! The rxn: Na + (g) + Cl !...
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- Spring '07