STRUCTURE QUESTIONS 1. The following table shows the relative atomic mass of a few types of carbon. Substance Relative atomic mass Carbon-12 12.000 Carbon-13 13.0003 Graphite 12.011 Diamond 12.011 iv. How do the structures of diamond and graphite explain their electrical conductivities respectively? v. The reaction C(diamond) C(graphite) ; ∆H = -3 kJ / mol is exothermic. Explain why this reaction does not occur spontaneously. [8] (b) Carbon-14 can be formed by the reaction between cosmic rays and nitrogen in the atmosphere. i. What are cosmic particles? ii. Write a balanced equation for the above reaction. [2] (a) i. Explain why carbon-12 replaced oxygen as a standard in the determination of relative atomic mass. ii. Why does the relative atomic mass of diamond differ from that of carbon-12? iii. Calculate the percentage of 12 C in graphite. 2. Beams of particles travelling at the same speed from different sources are subjected to an electric field as shown in the diagram below. A beam of neutrons has already been drawn (a) Sketch and label on the diagram above how beams of each of the following particles are affected by the electric field: (i) protons (ii) electrons (iii) 2 H + [3] (b) Explain briefly the position and shape of each beam. (i) protons (ii) electrons (iii) 2 H + [3] 3. (a) Describe the relative charges and masses of the three types of particles containing within the atom. How do beams of these particles behave in an electric field? [6] (b) Because of differing proportions of isotopes, the relative mass of lead depends on its source. Two samples of lead were subjected to analysis. The mass spectrum of the first sample was taken and the following results were obtained m/e value 204 206 207 208 relative abundance 27 48.0 41.5 100.0 When 1.00 g of the second sample was converted into lead (II) chloride, the mass of the product was 1.341g. Calculate the average relative atomic mass of each sample of lead, and decide whether or not the two samples have identical isotopic compositions. [Take the relative atomic mass of chlorine to be 35.45] [4] 4. The mass spectrum of naturally occurring magnesium is given below 24 25 26 m/e (a) Name the ions that are responsible for the peaks at positions 24, 25, dan 26 respectively. (b) Calculate the relative abundance of each isotope. (c) Calculate the relative atomic mass of magnesium. [6] 8 1 1 PPU 962 Chemistry 1 of 2 PPU 962 Chemistry: SEM 1, Chapter 1 = Atoms, Molecules and Stoichiometry This document is not under copyrights of LRT Documents. The questions above is not printed question.