Download Sodium Carbonate - Chemistry - Exam and more Exams Chemistry in PDF only on Docsity! Ollscoil na hÉireann, Gaillimh THE NATIONAL UNIVERSITY OF IRELAND, GALWAY __________________________________ AUTUMN EXAMINATIONS, 2010 __________________________________ FIRST MARINE SCIENCE EXAMINATION FIRST HEALTH AND SAFETY SYSTEMS EXAMINATION __________________________________ CHEMISTRY CH102 Martin Wills, D.Phil (Oxhon) Professor P.V. Murphy Dr. P. O’Leary Time allowed: Two hours Answer four questions, one from each section. All questions carry equal marks. Atomic masses: H: 1.008; C: 12.011; N. 14.007, O, 15.999 Molar volume at STP= 22.4 dm3, Avogadro’s Number 6.02 x 1023 Section A 1. Answer each of the following: (a) metronidazole was found to contain 41.88 % C, 5.27 % H, 24.42 % N and the remainder was oxygen. Calculate its empirical formula. Given that its molecular mass is gmol-1 what is its molecular formula. [10 Marks] (b) Write a chemical formula for each of the following: (i) Calcium chloride (ii) zinc(ii) oxide (iii) Sodium carbonate [6 Marks] (c) Balance the following equation C4H8O + O2 [4 Marks] (d) Suggest the structure of one molecule which might have the formula C4H8O [5 Marks] 2. Answer each of the following: (a) Write short notes on (i) Boyle’s and Charles’ laws [5 marks each part] (b) A sample of gas has a volume of 6 dm3 at 3 atm pressure and a temperature of 42˚C. What volume in dm3 will this gas occupy at 3.3 atm and 56˚C? [10 Marks] (c) How many Nitrogen molecules are contained in 17 dm3 of Nitrogen gas at standard temperature and pressure? How many Nitrogen atoms are present? [5 Marks] Section B 3. Answer each of the following: (a) Write out the electronic configuration of the following elements. (i) Carbon, (ii) sulfur. [8 marks] (b) Identify an ion which is isoelectronic with calcium and an ion which is isoelectronic with chlorine. [4 Marks] (c) In the compounds below identify the types of bonding present (ionic, polar covalent or covalent). (i) NaCl (ii) NH3 (iii) C2H2 [6 Marks] (d) The atomic mass of potassium is 39.0983amu. Explain why this is not a whole number given a proton and neutron both have a mass of 1 amu. [7 Marks] 4. Answer each of the following: (a) Explain the effect on the rate of a reaction of the following alterations in the reaction conditions: (i) a solid which is to react is used as a fine powder rather than in larger particles. (ii) the temperture at which the reaction is conducted is doubled . (iii) A catalyst is introduced to the reaction [3 x 3 Marks] (b) Write a balanced equation for the reaction of HCl and KOH. [3 Marks] (c) 15 cm3 of a 0.1 M solution of HCl are reacted with 5 cm3 of a 0.5 M solution of KOH. Given this information calculate the following: (i) Which is the limiting reagent? (ii) How many moles of the excess reagent are left unreacted at the end of the reaction? [13 Marks] Section C 5. Answer each of the following: (a) Draw structural formulae showing all the atoms of both of the following: (i) 2-ethyloct-1-ene, (ii) 3,3-chloroheptane . [8 marks] (b) Name each molecule and indicate the functional group present in the following molecules (i)-(vi): [2×6 marks] Question continues overleaf… Cl H2N O ON O OH (i) (ii) (iii) (iv) (v) (vi)
