課程名稱︰普通化學甲
課程性質︰
課程教師︰曾文碧
開課系所︰大氣系 地質系 農化系
考試時間︰2005/01/14
試題 :
R=0.08206 L*atm*K^-1*mol^-1 =8.3145 J*K^-1*mol^-1,
0度C=273K, Ka(HF)=7.2*10^-4, Kb(NH3)=1.8*10^-5
Van't Hoff equation: ln(K2/K1)=-(ΔH^0/R)[1/T1-1/T2]
(1) For the following reaction:2 NO2 <=> N2O4 (g)+58J,
in which direction will the position of the equillibrium be shifted
for each of the following changes (10%)
a.He(g) is added
b.N2O4(g) is added
c.NO2(g) is added
d.The temperrature is decreased
e.The volum of container is increased
(2) Calculate the pH of a 1.00M solution of HF (5%)
(3) A buffered solution contains 0.20M NH3 and 0.60M solution of HN4Cl.(10%)
(a) Calculate the pH of this solution,
(b) Calculate the pH of the solution that results when 0.10mol of gaseous
HCl is added to the buffered solution from part (a).
(4) Calculate the pH of a 1.0M NaH2PO4 (For H3PO4, Ka1=7.5*10^-3,
Ka2=6.2*10^-8, Ka3=4.8*10^-13) (5%)
(5) Briefly state the three laws of thermodynamics. (9%)
(6) Why is ΔH odtained directly from the heat flow using a coffee cup
calorimeter and ΔE odtained directly from the heat flow using a
bomb calorimeter? (6%)
(7) Consider 2.00 mol oh a monatomic ideal gas that is taken from state A
(Pa=2.00 atm, Va=10.0 L) to state B (Pb=1.00 atm, Vb=30.0 L) by two
different patways:
Pathway one: step 1:(Pa=2.00 atm, Va=10.0 L)→(Pc=2.00 atm, Vc=30.0 L)
step 2:(Pc=2.00 atm, Vc=30.0 L)→(Pb=1.00 atm, Vb=30.0 L)
Pathway two: step 3:(Pa=2.00 atm, Va=10.0 L)→(Pd=1.00 atm, Vd=10.0 L)
step 4:(Pd=1.00 atm, Vd=10.0 L)→(Pb=1.00 atm, Vb=30.0 L)
(a) Calculate q, w, ΔE, and ΔH for each of the 4 steps. (16%)
(b) Calculate q, w, ΔE, and ΔH for both patways. (8%)
(c) Among q, w, ΔE, and ΔH, which two are state functions? Why? (4%)
(8) For the following process:H20(l) → H2O(s), one expects that ΔS<0.
In the real world, water spontaneously freezes at -10度C. Why?
[Give a reasonnable interpretation on the basis of the second law of
thermodynamics.] (6%)
(9) Consider the reaction: 2SO2(g) + O2(g) → 2SO3(g) carried out at 25度C
and 1 atm. calculate ΔH^0 , ΔS^0 , and ΔG^0 ,using the following data.
(6%)
________________________________________________________
Substance ΔHf^0(kJ*mol^-1) ΔS^0 (j*k^-1*mol^-1)
---------------------------------------------------------
SO2(g) -297 248
SO3(g) -396 257
O2(g) 0 205
_________________________________________________________
(10) The value of Kp=3.7*10^-6 at 900K for the ammonia synthesis reaction.
Assuming the value of ΔH^0 for this reaction is -92kJ, calculate the
value of Kp at 600K. (6%)
(11) A 1.50mol sample of an ideal gas is allowed to expand adiabatcally and
reversibly to twice its original volime. In the expansion the temperature
dropped from 296K to 239K. Calculate ΔE^0 and ΔH^0 for the gas
expansion. (8%)
(12) When most biological enzymes are heated, they lose their catalytic
activity, the change: Original enzymes → new form that occurs upon
heating is endothermic and spontaneous.
Is the structure of the original enzymes or its new formmore ordered?
Explain your answer. (5%)
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