OCR A Jun 2014 Paper 1 Q6

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10 PMT This question is about Group 2 elements and compounds. (a) Group 2 carbonates undergo thermal decomposition. (i) Write the equation for the thermal decomposition of calcium carbonate. Include state symbols.[1] (ii) Write the formula of the Group 2 carbonate which decomposes at the highest temperature.[1] (b) Hydrated strontium chloride, SrCl26H2O, has a molar mass of 266.6 g mol1. A student heats 5.332 g of SrCl26H2O. The SrCl26H2O loses some of its water of crystallisation forming 3.892 g of a solid product. Use the information above to determine the formula of the solid product. Show your working. formula of solid product =[3]OCR 2014<br />
 11 PMT (c) A chemist carries out reactions of barium and barium nitride, Ba3N2. Reaction 1 Barium is reacted with water. Reaction 2 Reaction 3 Barium nitride is reacted with water, forming an alkaline solution and an alkaline gas. Barium is reacted with an excess of oxygen at 500C, forming barium peroxide, BaO2. (i) Write equations for Reaction 1 and Reaction 2. Ignore state symbols. Reaction 1:Reaction 2:[3] (ii) Predict the structure and bonding of Ba3N2.[1] (iii) BaO2 formed in Reaction 3 contains barium and peroxide ions. The peroxide ion has the structure [OO]2. Suggest a dot-and-cross diagram for BaO2. Show outer shell electrons only. [1] [Total: 10] END OF QUESTION PAPEROCR 2014<br />

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