GHW #9 CHEM 2811(01) Winter 2012. CHAPTER 4.
1. Using Pauling rules calculate the  pKa  values of HClO3 and  HClO4. What is the stronger acid?

2. The pKa value of HAsO4 2– is 11.6.  Is this value consistent with the two Pauling rules?

3.  Calculate ∆G0 for autoprotolysis of H2O and NH3 using values of Kw = 1x10-14 and Kam = 1x10-33. Which compound is the stronger acid?

4.	What is solvent leveling and how does it affect the acidity and basicity of compounds when dissolved in them. 

5. Using Pauling's rules (consult the table of examples given in the textbook, and consider also their conjugates), and taking the concept of solvent leveling into account, identify which bases from the following lists are (a) too strong to be studied experimentally; (b) too weak to be studied experimentally; or (c) of directly measurable base strength under the conditions specified:

a)	in water solution: (a) CO32–  ( pkb = 6), (b) ClO4 –( pkb = 21), and (c) NO3 – ( pkb = 16)

b)	In liquid H2SO4 solution: HSO4 – ( pkb =16),, NO3 –( pkb = 16), ClO4 - ( pkb = 21),

6.	What is hard/ soft  acid/base and acid base (HSAB) theory? 

7. Using HSAB concepts, which of the following reactions are predicted to have an formation (equilibrium) constant greater than 1?
Unless otherwise stated, assume gas phase or hydrocarbon solution and 25°C.
a)	R3PBBr3 + R3NBF3 ⇄ R3PBF3 + R3NBBr3 (Note: I have to use ⇔ to indicate equilibrium.)
b)	SO2 + (C6H5)3PHOC(CH3)3 ⇄ (C6H5)3P SO2 + HOC(CH3)3
c)	CH3HgI + HCl ⇄ CH3HgCl + HI
d)	[AgCl2]– (aq) + 2 CN– (aq) ⇔ [AgCN2]– (aq) + 2 Cl– (aq)

8.  Propose routes for following preparations. 
a)      C2H2 from CaC2 

b) P(CH3)3 from PCl3
9. Select the compound in each set (indicated by {}) with the named characteristic, and justify your choice:
a)	 Strongest Lewis acid: {BF3 ; BCl3 ; BBr3} {BeCl2 ; BCl3} {B(nBu)3 ; B(tBu)3}

b)	 More basic towards B(CH3)3: {(CH3)3N ; (CH3CH2)3N} {2-methylpyridine ; 4-methylpyridine}

8. Classify each Lewis acid and each Lewis base in the following complexes as hard, soft or borderline:
a) Zn(OH)4 -2	b)	Ag(CN)2 -	c) TiF4

9. Predict the product(s) of the following reactions. Use the Lewis acid/base approach, and any principles developed in the course to guide your predictions. Identify the acids and bases involved and categorize each reaction as (i) acid displacement, (ii) base displacement, (iii) complex formation or (iv) metathesis.

a)	Me3P-BF3 + Et3N-BBr3 → Me3P-BBr3 + Et3N-BF3
b) SO2 + AsMe3 → O2S4—:AsMe3
c) KF + PF5 → [K]+ [PF6]

10. Explain the Lewis acidity observed in the following series: 
a) BF3 < BCl3 < BBr3
b) SiI4 < SiBr4 < SiCl4 < SiF4

11. Explain the role of Al2Cl6 as a Lewis acid in Friedel Craft Acylation of benzene.