Invigilating CHEM244 Analytical Chemistry II

Just came back from invigilating the Analytical Chemistry module. Lol. This is not the first time I am invigilating. Last year, I invigilated for SCHO as well (well, I set the organic Q, that's why).

Anyway, this was the first time I saw those act-cute students having such a serious look on their face. Must be stress out from exams. Ha. When I saw the exam papers, I was stunned! It was quite easy lor. I am no expert in Analytical Chemistry but when I looked through the questions, I can do at least half of them lor. Lol. I think if TX, Eugene or Wu Jiang do, 1 hour can finish already. The questions are straightforward lor - section 1: MCQ, section 2: short answers and section 3: calculations. *faint* NUS analytical chemistry exam is comparatively tougher lor.

Ha come to think of it, NUS's exams standard is not that bad afterall. Last time, Zhijie and I always complain but on the whole, it is better and more organized compared to those in HK. I like those questions by Prof. Hor, Dr. John Yip, Prof. Lai, etc. The most memorable one being Prof. Hor CM3212's section A (50 marks):

Examine the validity of the following statements. By using suitable illustrations wherever applicable, explain concisely (in fewer than 80 words) the problem(s), if any, in each of these statements.

a. Synthesis of cis-PtCl2(NH3)2 (cis-platin) is best carried out through oxidation of Pt(NH3)4 by Cl2, although it can also be prepared from reduction of PtCl4 in aq. NH3.

b. Since trans-influence is a thermodynamic perturbation, it may have very little bearing on the labilizing effect of a departing ligand, which is governed by a kinetic phenomenon, called trans-effect. This is particularly true in substitution reactions that are driven by an associative mechanism.

c. [Rh2(miu-S)2(CO)2(miu-dppm)2] (dppm = Ph2PCH2PPh2) is a good example of an "A-frame" complex. The Rh-Rh bond can be easily cleaved to accomodate an incoming small molecule, such as SO2, without disturbing the 16-electrons state.

d. Dimerization of [Re(O)Cl4] should be facile, since it can generate a dinuclear species [Cl4Re-O-O-ReCl4] with octahedral geometry at the metal. The {Re2O2} core should be a stable entity since similar {M2O2} configuration has been established elsewhere, e.g. in [Co2(O2)(CN)10]6-.

e. Ln3+ is a labile metal ion. Transfer of ligand from Ln3+ to other metals ions (such as Cu2+) is necessarily quick and hence the rate constant k is inevitably very high.

Lol. 50 marks for section A. Section B requires us to read a paper and then answer 10 MCQ. Sounds simple? Not really. The above is a killer. It wiped out all except 2 in the exam. I remembered Zhijie writing only 2 pages for the above 5 Q as he thought the above 5 Q adds up to only 10 marks. Lol. In the end, he got an A. Wow.