JJC_H1 Chemistry 8872_H1 Prelim Paper 2

JURONG JUNIOR COLLEGE PRELIMINARY EXAMINATION 2008 H1 CHEMISTRY PAPER 2 8872 / 2 Monday 18 August 2008 2 hour Name: _______________________ (Index no.:____) Class: 07_____ INSTRUCTIONS TO CANDIDATES Do not open this booklet until you are told to do so. Write your name and index number and class in the spaces at the top of this page. Write in dark blue or black pen in the spaces provided on the Question Paper. You may use a pencil for any diagrams, graphs, or rough working. Do not use highlighters or correction fluid. Answer all questions. FOR EXAMINER’S USE Section A 1 2 3 4 Section B INFORMATION FOR CANDIDATES A Data Booklet is provided. Do not write anything on the Data Booklet. The number of marks is giv en in brackets [ ] at the end of each question or part question. You are advised to sh ow all workings in calculations. You may use a calculator. TOTAL / 80 This question paper consists of 12 printed pages, including this page. [Turn over Page 1 of 12

SECTION A (40 MARKS) Answer all questions in the space provided. 1. World War I is sometimes known as 'the Chemists' War'. Knowledge of chemistry was applied towards developing high expl osives and new methods of warfare such as the large scale use of poison gas. Fritz Haber, a German chemist, worked on t he use of chlorine as a poison gas. The first successful use of chlorine was at Ypres, Belgium, on 22 April 1915. 170 tonnes of chlorine cont ained in 5730 cylinders was released forming a grey- green cloud which drifted across French troops. Chlorine can damage the eyes, nose, throat and lungs and is fatal at concentrations of 1000 ppm and above (1 ppm = 1 mg dm −3). Early counter-measures to chlorine included instructing troops to cover their mouths with gauze pads soaked in sodium hydrogen carbonate solution. Occasionally urine was used instead of the sodium hydrogen carbonate solution. Eventually, more effective counter-measures to chlorine were developed and thus other poison gases were introduced. Victor Grignard, a Nobel Prize-winning chemist, worked on the manufacture of phosgene for France. Phosgene was deadlie r than chlorine but some of the symptoms of exposure only showed up after 24 hours. Thus victims were initially still capable of continuing fighting. The most effective gas used in World War was mustard gas, a blistering agent. Mustard gas did not have to be inhaled but attacked any exposed area of skin. Mustard gas often did not kill outright but it caused horri fic injuries which strained medical resources. (a) (i) Calculate the maximum amount of chlorine gas that could have released from one of the cylinders t hat was used at Ypres on 22 April 1915. (1 tonne = 1000 kg) (ii) Determine the concentration of chlorine gas, in mol dm −3, at 1000 ppm. Page 2 of 12

1. (a) (iii) In an accident, the chlorine gas from one such cylinder