1. Explain:   (15)
   (a) Molecule can have polar bonds yet be classified as nonpolar.
   (b) The electron pair geometry for water is tetrahedral but the molecular shape is bent.
   (c) Electronegativity increases from left to right on the periodic table.
   (d) NF₃ posseses permanet dipole while CF₄ has temporary dipole.
   (e) Water has unsually high boiling point for a small molecule.

2. Write electron dot structures (show nonbonding pair):  (12)
    (a) CH₅N       (b) HBrO₂       (c) CO₃^-2        (d) PO₃^-3

3. Draw structure with correct geometry and indicate positive/negative poles (d+/d-) if applicable:
    (a) CHCl₃   (b) NF₃    (c) OF₂   (d) SiI₄                      (12)

4. Explain whether the following pairs are miscible or immiscible: (12)
    (a) water & KBr     (b) water & SF₂     (c) CH₄ & NCl₃     (d) LiNO₃ & CH₃CH₂CH₂CH₃

5.  Calculate:   (10)
     (a) [OH^-1] when [H⁺¹] = 3.55x10^-5         (b) pH when [H⁺¹] = 8.26x10^-4 M
     (c) [OH^-1] when pH = 10.65                    (d) pH when [OH^-1] = 6.25x10^-11
     (e) [H⁺¹] when pH = 2.83

6. Acid-Base Related:      (10)
    (a) How much more acidic is pH of 2 than pH of 5?
    (b) Write net ionic equation for HNO₃(aq) + KOH(aq)
    (c) Which of the following is not a buffer?   HCl/NaCl   HNO₂/NaNO₂   HClO/NaClO
    (d) Define a strong Bronsted-Lowry acid.

7.  Calculate:  (30)
     (a) Calories needed to change 45.0g ice at -33°C to liquid water at 85°C
     (b) Percent water for Mg(ClO₄)₂^.6H₂O
     (c) Molarity if 37.0 mL of 5.00M HCl diluted to 115 mL
     (d) Mass/mass percent of 3.00M KNO₃ (d = 1.12 g/mL)
     (e) Mass K₂CO_3(s) needed to react with 35.0 mL of 1.50M Pb(NO₃)_2(aq)
           K₂CO_3(s)  +  Pb(NO₃)_2(aq) 2KNO_3(aq) +  PbCO_3(s)
      (f) Mass KBr in 75.0g of 12.0% KBr solution.

Answers
1.   (a) Molecular polarity depends on polar bonds as well as molecular geometry. If polar bonds cancel, the molecule
            will be nonpolar
      (b) Oxygen, the central atom, has 2 bonding pairs & 2 nonbonding pairs. The molecule is tetrahedral if the
            nonbonding pairs are included in the shape. The molecule is bent if only hydrogen and oxygen considered
            for the shape.
      (c) Electronegativity represents an atom affinity for electrons. Metals are positioned to the left and nonmetals to the
            right of the periodic table. Since nonmetals have tendency to gain electrons, electronegativity increases left to
            right.
      (d) NF₃ is polar while CF₄ is nonpolar. Polar molecules exhibit permanent dipole while nonpolar molecules exhibit
            temporary dipoles.
      (e) The relatively high boiling point of water is due to hydrogen bonding, the strongest intermolecular force.

4.  (a) Miscible since water highly polar and KBr ionic.
     (b) Miscible since water & SF₂ are both highly polar.
     (c) Miscible since CH₄ & NCl₃ are both nonpolar.
     (d) Immiscible since components are ionic & nonpolar.

5. (a) [OH^-1] = 2.82x10^-10     (b) 3.08     (c) 4.47x10^-4     (d) 3.80     (e) 1.48x10^-3

6.  (a) 1000 times
     (b) H⁺¹ + OH^-1 H₂O_(l)
     (c) HCl/NaCl   (HCl is strong acid)
     (d) Great tendency to transfer proton

7.  (a) Q = (45.0)[(1)(.50)(33) + (80) + (1)(1)(85)] = 8170 cal

     (b) % H₂O = (108/331) x 100 = 32.6%

     (c)                    M₁V₁  =  M₂V₂
           (5.00M)(37.0 mL) = M₂(115 mL)    M₂ = 1.61M
     (d) Assume 1.00L      mass of solution = 1120g     mass KNO₃ = 3(101g) = 303g
           m/m % = (303/1120) x 100 = 27.1%

     (e)  mol K₂CO₃ = mol Pb(NO₃)₂
                 (g/FW) = (M)(L)
                 (g/138) = (1.50)(0.0350)         g = 7.25g K₂CO₃
     (f) (75.0g Soln)(12.0g KBr/100g Soln) = 9.00g KBr