OCR A Jun 2011 Paper 1 Q5

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5 Solids exist as lattice structures. 12 (a) Giant metallic lattices conduct electricity. Giant ionic lattices do not. If a giant ionic lattice is melted, the molten ionic compound will conduct electricity. Explain these observations in terms of bonding, structure and particles present.[3] (b) The solid lattice structure of ammonia, NH3, contains hydrogen bonds. (i) Draw a diagram to show hydrogen bonding between two molecules of NH3 in a solid lattice. Include relevant dipoles and lone pairs. [2] (ii) Suggest why ice has a higher melting point than solid ammonia.[2]OCR 2011<br />
 13 (c) Solid SiO2 melts at 2230 C. Solid SiCl4 melts at 70 C. Neither of the liquids formed conducts electricity. Suggest the type of lattice structure in solid SiO2 and in solid SiCl4 and explain the difference in melting points in terms of bonding and structure. In your answer you should use appropriate technical terms, spelled correctly.[5] END OF QUESTION PAPER [Total: 12]OCR 2011<br />

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