OCR A Jan 2012 Paper 1 Q4

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4 Solid potassium, K, solid potassium bromide, KBr, and ice, H2O, all exist as lattices. Their melting points are shown in the table below. (a) Complete the table. solid melting point / C KBr H2O 63 734 type of lattice giant metallic [2] (b) Explain why there is a difference in the melting points of K, KBr and H2O. In your answer you should refer to the types of particle, the types of forces between the particles and the relative strength of the forces between the particles in solid K, KBr and H2O. In your answer, you should use appropriate technical terms spelled correctly.[6]OCR 2012<br />
 (c) Potassium metal reacts with water. 2K(s) + 2H2O(l) 2KOH(aq) + H2(g) 0.2346 g of potassium is reacted with excess water. Calculate the volume of gas formed. The gas volume is measured in cm3 at room temperature and pressure. answer =cm3 [3] [Total: 11]OCR 2012 Turn over<br />

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