Final Test CHEM 3121 and 6111 December 10 th, 1997

Transcription

1 Name: Final Test CHEM 3121 and 6111 December 10 th, 1997 Numbers in bold indicate the maximum points available for that question. 1) Give the ground state electron configurations for the following atoms and ions. 3 Ni Ni 2+ Tl 3+ 2) a) Which of the following is likely to have the largest second ionization energy. 2 Rb, Sr or In b) Which of the following will have the lowest first ionization energy. 2 Be, Mg, or Ca

2 3) Construct and label an MO diagram for O 2. 3 Calculate the bond orders for O 2 +, O 2, O 2 - and O Order the four species according to their bond lengths, shortest first. 2 Which of the species are paramagnetic? 1 4) With the aid of an MO diagram explain why XeF 2 is a stable molecule (in other words explain the bonding in this molecule). Is XeF 2 an example of an electron deficient or an electron rich molecule? 4

3 5) List the symmetry elements for each of the following molecules and use the attached flow chart to assign a point group for each of them. 4 a) BF 3 (has a trigonal planar structure) F B F F b) CH 2 Cl 2 H H Cl Cl 6) Which of the above species, if any, (in question 5) are polar? 1 7) Use VSEPR to predict the structures of the following compounds (give the total valence electron count and draw the structure). 4 a) SF 4 b) SO 3 2-

4 8) 1M solutions of the following salts were prepared in water. The ph of each solution was measured. List the salts according to the acidity of the solution it formed putting the salt forming the most acidic solution first. 4 CsNO 3, KNO 3, Fe(NO 3 ) 2, Fe(NO 3 ) 3 9) Order the following Lewis acids according to their acid strength. Put the strongest acid first. BF 3, BBr 3, BCl 3 10) For each of the following equilibria indicate whether the equilibrium will lie in favor of the reactants or the products (hint use Hard-Soft acid-base principle). 6 AgF + NaI == AgI + NaF TiF 4 + 2TiI 2 == TiI 4 + 2TiF 2 Et 2 SBH 3 + Et 2 OBF 3 == Et 2 SBF 3 + Et 2 OBH 3 11) Describe the structures of the following compounds using the idea of filling holes in a close packed array of ions. 6 NaCl NiAs CdI 2

5 12) The Drago-Wayland relationship is usually given in the form - H = E a E b + C a C b. Calculate the Drago-Wayland parameters E and C for Iodine given the following data. i) the enthalpy of reaction between acetone and iodine is kcal mol -1, ii) the enthalpy of reaction between ammonia and iodine is kcal mol -1, iii) the Drago-Wayland parameters for acteone are E = 2.02, C = 4.67 and iv) the Drago-Wayland parameters for ammonia are E = 2.78 and C = Estimate the enthalpy of reaction between pyridine and iodine in the gas phase given that the Drago-Wayland parameters for pyridine are E = 2.39 and C =

6 13) Predict the structures of MgO and GaP using both the radius ratio rules and the structure map given bellow. 4 Ionic radii in pm: Mg 2+ = 86, O 2- = 126, Ga 3+ = 76, P 3- = 200 Mulliken electronegativity: Mg = 1.37, O = 3.94, Ga = 2.01, P = ) a) Estimate the lattice energy for CaCl using the Kapustinski equation given the following data. Ionic radius of Ca + ~ 160 pm, ionic radius of Cl - = 167 pm. Kapustinskii equation: U 0 = (120,200νZ + Z - )(1-34.5/r 0 )/r 0 kj mol -1 (assumes r 0 is in pm) 2

7 b) Estimate the enthalpy change for the reaction 2CaCl (s) ---Å CaCl 2(s) + Ca (s) Given that the 1st and 2nd Ionization energies of calcium are 590 and 1,145 kj mol -1 respectively, the lattice energy of CaCl 2 is 2258 kj mol -1 and the enthalpy of atomization for calcium is 177 kj mol c) Is CaCl likely to be thermodynamically stable with respect to decomposition into its component elements? 1 d) Is it likely that CaCl could be prepared? 1 15) Give chemical equations for syntheses of the following organometallics 6 a) Methyl lithium b) Dimethyl mercury

8 c) Triethyl aluminum 16) Which of the following compounds is likely to be most reactive with water? 2 HgMe 2, SiMe 4, AlMe 3 17) Which of the following compounds would be most likely to react with a ketone to give a tertiary alcohol after workup? 2 HgMe 2, SiMe 4, CdMe 2, ZnMe 2 18) What are the likely products from the reaction of SiMe 2 Cl 2 with water? 2 19) List the main differences between the chemistry of disilenes and alkenes. 4

9 20) Zeolite A is typically made in the sodium form (Na + as extraframework cations). Ion exchange with solutions of calcium salts occurs readily. What effect does this ion exchange have on the effective pore size of the solid? 2 21) List two ways in which the Si/Al ratio of a zeolite effects its properties? 4 22) Give an example of an industrial process that makes use of shape selective acid catalysis with zeolites. 2

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