NJC_H3Prelim Questions 2008 (ver3)

NATIONAL JUNIOR COLLEGE Preliminary Examinations 2008 H3 CHEMISTRY 9812 12 Sep 2008 TIME: 2 hour 30 mins Additional Materials: Data Booklet Writing paper Do not open this booklet until you are told to do so. Write your name, class and registration number in the spaces provided at the top of this page. READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, class and registration number in the spaces provided on the answer cover sheet and on each piece of writing paper. Write in dark blue or black pen. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer any 5 questions on the writing paper provided. Start each question on a fresh piece of paper. A Data Booklet is provided. You are reminded of the need for good English and clear presentation in your answers. You may use a calculator. At the end of the examination, fasten all your work securely together with the cover sheet placed on top. The number of marks is given in brackets [ ] at the end of each question or part question. 1 This question paper consists of 13 printed pages (including this page)

1) This question concerns the investigation of a sports supplement by the Health Science Authority (HSA) of Singapore. HSA was called upon to investigate a new weight loss supplement, MusclePower, launched in 2008, that targets bodybuilding beginners who wish to shed off extra fats. MusclePower claimed that their pills are 100% herbal in origin and contains no illegal proprietary drugs. The label on the MusclePower claims that it does not contain Ephedrine, an amphetamine-like stimulant, which is banned in Singapore. The structure of Ephedrine is shown below. H N CH3 CH3 OH Ephedrine NH2 Amphetamine CH3 H N CH3 OH HO HO Adrenaline N NN N O O CH3 CH3 H3C Caffeine N N H CH3 Nicotine Ephedrine, together with caffeine, are common ingredient in many weight loss pills that speeds up metabolism and thus causes fats to burn faster. Before the former was banned in Singapore, body builders routinely consume them to increase performance. a) (i) Define what is meant by the term “stimulant”. [1] (ii) Compare the structure of Ephedrine with amphetamine and adrenaline. Highlight what structural features Ephedrine has in common with amphetamine and adrenaline respectively. [2] Many stimulants, such as the 5 listed above are basic compounds. One of the preliminary steps in the analysis of an herbal supplement is to isolate a subclass of compounds from the pills. MusclePower pills are of supposedly herbal origin and thus contain many natural organic compounds. 2

b) By means of simple glassware and common laboratory reagents, suggest how