1.   3 CaBr₂ + 2 Na₃PO₄   6 NaBr + Ca₃(PO₄ )₂        (12)
     (a) Calculate grams of CaBr₂ needed to react with 49.2 g Na₃PO₄.
     (b) Calculate volume of 0.350 M Na₃PO₄ solution needed to react with 25.0 mL of 0.500 M CaBr₂ solution.
     (c) 98.4 g of Na₃PO₄ allowed to react with 120. g CaBr₂. Which reactant in excess and by how many grams?

     2.  Compound containing CHN was burned and 2.20 g CO₂, 0.720 g H₂O, and 0.920 g NO₂obtained. (8)
          Determine empirical formula of compound:     CHN  +  O₂   CO₂  +  H₂O  +  NO₂

     3. Write balanced net ionic equations:   (8)
         (a) Al(NO₃)_3aq) + KOH_(aq)                (b) PbAc_2(aq) + Na₂SO_4(aq) 
         (c) K₂CO_3(aq) + HNO_3(aq)                 (d) NH₄Br_(aq) + KOH_(aq) 

     4. (a) Draw 3 resonance forms to represent SO₃ (show charges).    (4)
        (b) Calculate joules needed to raise the temperature of 50.0g of gold from 35.0°C to 75.0°C.  (4)
        (c) Calculate H for  NaHCO_3(s)  +  HCl_(g)   NaCl_(s)  +  H₂O(l)  +  CO_2(g)   (4)
         (d) Use Rydberg equation to determine energy levels for electron emitting radiation of 1283 nm. (4)

     5. Represent electrons using arrows/boxes:     (12)
         (a) N = 1,2,3            (b) N = 5            (c) N = 4        (d) N = 3
              M_L = +1                    L = 2                  L = 3             M_L= -3
              M_S = +½                 M_L= ±2              M_S= -½

     6. Draw Lewis structure with correct geometry (show lone pairs). If polar, indicate poles (d+/d-). (12)
         (a) SCl₄     (b) NI₃      (c) BrF₃       (d) XeF₄

     7. Draw valence bond sketch including nonbonding orbitals:  (12)
         (a) H-O-CN     (b) C₂F₆       (c) H₂C=S      (d) XeF₂

     8.  Balance the following half reactions:  (8)
          (a) NO₃^-1   NO         (acidic conditions)
          (b) BrO₂^-1    Br₂           (basic conditions)

     9. (a) Calculate partial pressure of Ar if 16.8g N₂, 16.0g Ar and 6.40g CH₄exert total pressure of 2.50 atm. (4)
         (b) Gas sample at 2.75 atm and 30.0°C occupies 350 mL. Calculate volume at 60°C and 3.25 atm. (4)
         (c) Ne effuses at 75.0 mL/min and gas X effuses at 30.0 mL/min. Calculate molar mass of X.  (4)
 

      Answers
     1. (a) 3 mol Na₃PO₄ = 2 mol CaBr₂       (b) 23.8 mL     (c) Na₃PO₄ excess by 0.200 mol or 32.8 g
              3(49.2/164) = 2(g/200)
              g = 90.0g

     2.  mol CO₂ = 0.0500 = mol C     mol H₂O = 0.0400  mol H = 0.0800    mol NO₂ = 0.0200 = mol N
         C_0.0500H_0.0800N_0.0200  =  C_2.5H_4.0N  =  C₅H₈N₂
 

     3. (a) Al⁺³ + 3OH^-1Al(OH)_3(s)                      (b) Pb⁺²  +  SO4^-2   PbSO_4(s)
         (b) 2H⁺¹  +  CO₃^-2   H₂O  +  CO_2(g)          (d) NH₄⁺¹  +  OH^-1   NH_3(g)  +  H₂O

     4.  (a)
          (b)  Q = msT = (50.0g)(0.129J/g/°C)(40.0°C) = 258J

          (c) H for  NaHCO_3(s)  +  HCl_(g)   NaCl_(s)  +  H₂O(l)  +  CO_2(g)
H =  -H(NaHCO_3(s))  - H(HCl_(g))    ₊ H (NaCl_(s))   + H (H_2(l))  + H(CO_2(g))
H =   - (-948kJ)  -  (-92kJ)   +  (-411kJ)  +  (-286kJ)  +  (-394kJ)  =  -51kJ

         (d) 53
 

     5. 

     6. 

     8. (a)  NO₃^-1 +  4H⁺¹  +  3e^-1   NO  +  2H₂O
         (b) 2BrO₂^-1 +  4H₂O   +   6e^-1   Br₂   +  8OH^-1

     9.  (a)   mol N₂ = 16.8/28 = 0.600      mol Ar = 16.0/40 = 0.400      mol CH₄ = 6.40/16 = 0.400
                  P_Ar = (0.400/1.40)(2.50 atm) = 0.714 atm
          (b)   V₂ = P₁V₁T₂/P₂T₁ = [(2.75 atm)(350 mL)(333K)]/[(3.25 atm)(303K)] = 325 mL
          (c)   m_X = m_Ne (U_Ne/U_X)² = (20.18 g/mol)(75.0/30.0)² = 126 g/mol