【正文】 is a catalyst B Gold Nanoparticles The synthesis and characterization of gold nanoparticles is currently an active research area. The BrustSchiffrin method for the synthesis of gold nanoparticle (AuNP) allows the facile preparation of thermally stable and airstable AuNPs of reduced polydispersity with a controlled size distribution ranging in diameter between and nm. The preparative procedure is briefly described as follows. An aqueous solution of HAuCl4 is mixed with a toluene solution of tetranoctylammonium bromide. The solution is mixed with dodecahiol and is treated with an excess of of the AuNPs is evidenced by the immediate, pronounced darkening of the toluene ca. 24 h, the toluene solvent is removed with a rotary evaporator and the resulting solid washed on a frit with ethanol and hexane to remove excess thiol. These AuNPs can be repeatedly isolated and redissolved in mon anic solvents without irreversible aggregation or deposition. 4B1 Is the methodology for this fabrication referred to a topdown or a bottomup approach? Select your answer from the following choices. (a) topdown approach, which entails reducing the size of the smallest structures to the nanoscale (b) bottomup approach, which involves manipulating individual atoms and molecules into nanostructures 第 28 頁(yè) 共 64 頁(yè) Country: Language: 4B2 The trimethylnoctylammonium bromide can also be used as a phasetransfer reagent. It can carry AuCl4175。 is a reducing agent (c) Cl175。 for the above reaction. Select your answer from the following choices. (a) Cl175。C: K = [AuCl4?] / [Au3+] [Cl?]4 4A6 The function of HCl is to provide Cl175。s historical legacy. It was the site of one of the largest gold mines In Asia. Accordingly, Chiufen is often referred to as the Gold Capital of Asia. The pound KCN is traditionally used to extract gold from ore. Gold dissolves in cyanide (CN) solutions in the presence of air to form Au(CN)2, which is stable in aqueous solution. 4Au(s)+8CN－ (aq)+O2(g)+2H2O(l) 4Au(CN)2－ (aq)+4OH－ (aq) 4A1 Draw a structure for Au(CN)2175。 C3: 。 (d, J = 6 Hz, 1H), (d, J = 6 Hz, 1H), (s, 1H). 25 Draw the configurational formula of H. 26 Assign R/S notations for pound I at C1, C2, C3 and C4. Give your answers as follows: C1: 。.Further purification by recrystallization gave pure E with the optical rotation [α]D20 = 176。 show the calculations). Remended scoring standard: We will double check the calculations, 5 points will be taken off for the wrong calculations. Points will be given based on the correct chemical yield. 14 Draw the correct configuration formula (stereo chemical structure) of the isolated phenylglycine. OO HN H 2OO HN H 2H C O O HP hN H 2H If only correct chemical structure is given (no stereo chemistry), 1 point is given. g/ 第 12 頁(yè) 共 64 頁(yè) Country: Name: 15 Specific rotation of the enantiomeric phenylglycine ? (+) CSA salt (to be determined by the anization mittee) Turn in the sample (in the vial with pink label). Signature of student: Signature of the lab assistant: [The anization mittee will weigh an appropriate amount of sample ( ~) for measurement of optical purity.] Remended scoring standard: The anization mittee will weigh the resolved product (from the fritted glass funnel) for students who fail to finish the procedure in time. However, 15 penalty points will be taken. 第 13 頁(yè) 共 64 頁(yè) Country: Name: Experiment 2 Identification of Unknown Inanic Samples Total Scores: 100 points 21 22 Σ Total Points 96 4 100 Received 21 Unknown Code Unknown Code Unknown Code Compound Number** Compound Number** Compound Number** HCl , H2SO4 , NH4SCN , NaOH , BaCl2 , K4SCN , Na2CO3 , ZnCl2 , Na2CO3 , H2O2 , **Second column is for duplicates. 22 A. Write the electrolysis equation that would help you confirm that an unknown sample is ZnCl2. Zn2+(aq) + 2Cl—(aq) → Cl 2(aq) (anode) + Zn(s) (deposit on cathode) B. Write one equation that shows how to clean the deposit of Zn on the electrode (limited to the items provided in this task). Zn(s) + 2H+(aq) → H 2(g) + Zn2+(aq) or Zn(s) + 2OH－ (aq) → H 2(g) + ZnO22― ―(aq) Country: Language: 37th IChO Theoretical Examination 第 14 頁(yè) 共 64 頁(yè) use only the pen provided time 5 hours problem booklet 26 pages (including this cover sheet) answer sheets: 28 pages (including cover sheet, and fives pages at the end with only a box. Use if necessary. Write down the problem number inside the box draft paper (will not be marked): 5 sheets (more are available on request) total number of points: 279 (They are equally weighted in the final score) your name and student code write on every answer sheet atomic masses use only the periodic system given constants use only the values given in the table answers only in the appropriate boxes of the answer sheets. Nothing else will be marked questions ask for show works no point will be given to no showing work restroom break ask your supervisor official Englishlanguage version available on request, for clarification only,you’re your supervisor. after the stop signal put your answer sheets in the correct order (if they aren’t), put them in the envelope (don’t seal), deliver t