Chem_mock_q - Times College Intensive Revision Course –...

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Unformatted text preview: Times College Intensive Revision Course – S- Men Chem-1 2006 i 1. a. An element has an isotopes 20 Y , 21 Y and 22 Y . The ratio of the abundance of 20 Y and 22 Y is 2 :1 and the relative atomic mass is 20.86. 20 2 Yø ,+1 Y and 22 Y. 20 Y and 22 Y x ~ C ´ ª 2 :1x ~ C ´ x~ C ´ª H 20.86. i. Find the value of the relative isotopic mass of each of the isotopes? Z « · ªH Ð I •D ii Comment on the statement of ‘ relative atomic mass of Y is 20.86. ‘ x ~ C ´ ª H ‘ Y x~ C ´ ª H 20.86 ‘ iii What is the percentage of isotope of 22 Y ? 22 x~C´ªH Y x ~C ´ ª ( 7 marks) b) Ammonium sulphate and urea can be used as fertilizers. Z«·ªH ÐI• D i. How can ammonium sulphate be manufactured from ammonia? Give the equation for the reaction involved. pìs·ªH € A ©· ª H l ii. Calculate the percentage by mass of nitrogen in urea and ammonium sulphate. pì s · ª H €A © ·ªH l . iii. What would these values be of interest to a farmer? Z«· ª H Ð I• D iv. Suggest two other factors which a farmer would consider before choosing a fertilizer. pìs· ª H €A © · ªH l ( 11 marks ) – S- ø Men i -1 Times College Intensive Revision Course – S- Men Chem-2 2. The structural formulae of three common detergents are shown below: X - « ·ª H Ð I •D X: OSO3-Na+ Y: COO-Na+ Z: COO-Na+ where . a) = hydrocarbon tail and i. ii = side branch. H{ C ´ ª H H{ C ´ ª Which one is a ‘ soapless detergent? )- « Name the starting materials for preparing detergent Y in the laboratory. Y pì s · ª H ) iii. What would be observed if sea water were shaken in a bottle with a small quantity of 1. detergent X 2. detergent Y ? pìs ·ª H m ©· ª H 1. . iv. X 2. . l YH Draw the part of detergent that can dissolve in grease. X- « · ª H Ð I•D – S-) Men i -2 Times College Intensive Revision Course – S- Men Chem-3 v. Draw the part of the anion of detergent X that would mix well with water. b{ C ´ ª H X Þ ° ·ª H Ð I•D vi. Which one of the above three detergents would cause the greatest pollution problem when discharge into rivers or the sea ? Suggest a reason for your answer. RfR RK • D ( ƒ~ R— ‘ w pK• D vii. To remove oil patches from the sea in costal areas , some detergent is sprayed over them. Explain the action of the detergents in this process. a =2R Rf R R K• D viii. Explain why detergents should not be used to remove oil patches near fish farms. p ì s ª· H m©·ªH l ( 11 marks ) b. Ethene undergoes polymerization to form a polymer X. Þ ° ·ª H ÐI •D X i. ii. iii. Name the polymer X. b { C ´ ª X. Write an equation for the polymerization of ethane. Þ ° · ªH Ð I•D 1. Is polymer X thermoplastic or thermosetting? . X Þ°·ªH Ð I D• 2. Given a small piece of X how would you show that it is the kind of polymer you stated in ( 1 ). b { C´ªH X Þ °·ªH ÐI •D ( 1 )b { C ´ ª iv. Give two other uses of X besides making plastic pipes. . X ø Ý° ( 7 marks ) – S- Men ø i -3 C Times College Intensive Revision Course – S- Men Chem-4 3. Excess zinc granules reacted with 50 cm3 of hydrochloric acid in a flask at room temperature and pressure. The volume of gas librated was measured at regular time intervals . A graph of the gas liberated against time was plotted as follows: ˆ zC ´ª H 50 cm3 RK • D a =2R P ± ° · ªH ÐI • D Volume of carbon dioxide ( cm3 ) ˆ z C ´ H ª ( cm3 ) 120 time ( min ). (. ) a) Suggest a piece of apparatus to measure the volume of gas librated. H±° · b) Write an equation for this reaction. H c) Calculate the concentration of the acid in mol dm-3 . ˆ z C ´ª H mol dm-3 . ( Molar volume of gas at room temperature and pressure = 24.0 dm3 ) (P ± ° · ª H ÐI• D = 24.0 dm3 ) d) Draw on the same graph the expected curve if the experiment is performed using the same volume of ethanoic acid with the same concentration instead of hydrochloric acid. Explain your answer. RfR RK • D ) ƒ~ R — ‘ w p K•D ( 8 marks ) 4. 1.1 2g of an unsaturated gaseous hydrocarbon X on complete combustion produce 3.52 g of carbon dioxide. The volume of oxygen used for complete combustion is 6 times the volume of X under room conditions. ( Relative atomic masses : H = 1.0 , C = 12.0 , O = 16.0 ; Molar volume of gas at room temperature and pressure = 24.0 dm3 ) – S- H Men i -4 Times College Intensive Revision Course – S- Men Chem-5 1.12 g ¨ y C ´ ª H X ( ; 3.52g p ì s · ª H . X ¨y C ´ ª H (¨ y C´ª : H = 1.0 , C = 12.0 , O = 16.0 X I ° · ª H ÐI • D l ©·ª* o = 24.0 dm3 ) a) In 1.12 g of X , what are the masses of carbon and hydrogen. . 1.12g . X )I °· b) Find the empirical formula of x. . x¨y C´ª c) Find the molecular formula of X. . x¨y C ´ ª d) Draw TWO possible structure of X. pK•D ï I•D – S- ) Men ( 8 marks ) i -5 ...
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