105年 - 105 國立嘉義大學_轉學生招生考試試題_應用化學系：普通化學#144897

1. Discuss briefly the difference between an orbit (as described by Bohr for hydrogen) and an orbital (as described by the wave mechanical model) (10 %)

2. What are the dissociation percent of 10.0 M and 0.1 M acetic acid at 20 ℃? (K_a for acetic acid at 20 ℃ is 1.0 x 10^-5) (10 %)

3. Determine the molecular formulas for a compound that gives the following percentages on analysis (in the mass percents) (10 %)
71.65 % for Cl, 24.27% for C, 4.07% for H,
The molar mass is known to be 98.96 g/mol. (The atomic mass of C is 12.01, H is 1.008, Cl is 35.45)

4. For a reaction at 1 atm
Br_2(l)→ Br_2(g)
Where ∆H° = 31.0 kJ/mol and ∆S° = 93.0 J K-1mol^-1
What is the normal boiling point of liquid Br₂. (10 %)

5. Calculate the useful pH range for Bromothymol blue, an indicator with a Ka value of 1.0 × 10^-7 . (10 %)

 (a) pure water and

(b) 0.1 M silver nitrate. (10 %)

7. For the oxidation-reduction reaction
S₄O₆^2-_(aq) + Cr²⁺_(aq)→ Cr³⁺_(aq) + S₂O₃^2-_(aq) ε°cell = 0.48V
the appropriate half-reactions are
S₄O₆^2-_(aq) + 2e^- →S₂O₃^2-_(aq) ε° = 0.17V
Cr³⁺_(aq) + e^- →Cr²⁺_(aq) ε° = -0.50V
Balance the redox reaction and calculate εo and K (equilibrium constant)? (10 %)

8. Which of the following are predicted by the MO model to be unstable diatomic species? (H₂⁺, H₂, H₂^2-, He₂, He₂²⁺, He₂^2-, Li₂, Li₂²⁺) Explain why? (10 %)

9. Why the half-life of a first-order reaction does not depend on concentration of reactants? Explain your answer by deriving the integrated rate law. (10 %)

10. For the reaction between nitric oxide and hydrogen,
2NO_(g) + H_2(g) →N₂O_(g) + H₂O_(g)
may proceed via the following mechanism:
1. 2NO \(\xrightarrow{k_1}\) \(\xleftarrow{k_{-1}}\) N₂O₂
2. N₂O₂ + H₂ \(\xrightarrow{k_2}\) N₂O + H₂O
Write the rate law for this reaction by using the steady-state approximation if step 2 is the rate-determining step in this mechanism. (10 %)