Suggest the type of bonding in and structure of si 3

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Suggest the type of bonding in and structure of Si 3 N 4 . Explain your answer. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ....................................................................................................................................... [3]
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5 9701/22/O/N/19 © UCLES 2019 [Turn over (c) Sulfur-containing compounds, such as C 2 H 5 SH, are found in fossil fuels, and produce SO 2 when they are burned. (i) Write the equation to show the complete combustion of C 2 H 5 SH. ....................................................................................................................................... [1] (ii) State why the presence of SO 2 in the atmosphere has environmental consequences. Describe one of the consequences on the environment. ............................................................................................................................................. ............................................................................................................................................. ....................................................................................................................................... [2] (d) SO 2 can react with ozone, O 3 , to form SO 3 in two different reactions. (i) In one reaction, SO 2 reacts with O 3 until a dynamic equilibrium is established. SO 2 (g) + O 3 (g) SO 3 (g) + O 2 (g) State and explain the effect of an increase in pressure on the composition of the equilibrium mixture. ............................................................................................................................................. ............................................................................................................................................. ....................................................................................................................................... [2] (ii) In the other reaction, a different equilibrium is established at 300 K as shown. 3SO 2 (g) + O 3 (g) 3SO 3 (g) Δ H = +462.3 kJ mol –1 Suggest a temperature needed to increase the yield of SO 3 at equilibrium. Explain your answer. ............................................................................................................................................. ............................................................................................................................................. ....................................................................................................................................... [2] [Total: 19]
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6 9701/22/O/N/19 © UCLES 2019 2 Oxygen is the most abundant element in the Earth’s crust. It reacts with other elements to form stable compounds, ions and molecules. (a) Complete the table to give the formulae and acid/base behaviour of some of the oxides of the Period 3 elements. element sodium aluminium silicon phosphorus sulfur formula of oxide Na 2 O SO 3 acid/base behaviour amphoteric [2] (b) Group 2 elements form stable hydroxides, with general formula M(OH) 2 , where M is the Group 2 element. (i) Beryllium hydroxide, Be(OH) 2 , is an amphoteric compound that shows similar chemical reactions to aluminium oxide. State the meaning of the term amphoteric . ............................................................................................................................................. ....................................................................................................................................... [1] (ii) Write an ionic equation for the reaction of magnesium hydroxide, Mg(OH) 2 , with hydrochloric acid. ....................................................................................................................................... [1] (iii) Two methods of preparing strontium hydroxide are shown. strontium strontium hydroxide strontium oxide H 2 O reaction 1 H 2 O reaction 2 State one difference between the observations you would make for reaction 1 and reaction 2 . ............................................................................................................................................. ............................................................................................................................................. ....................................................................................................................................... [1] (iv) State how the solubility of the Group 2 hydroxides changes down the group. ....................................................................................................................................... [1]
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7 9701/22/O/N/19 © UCLES 2019 [Turn over (c) Sodium peroxide, Na 2 O 2 , reacts with CO 2 . Na 2 O 2 (s) + CO 2 (g) Na 2 CO 3 (s) + 1 2 O 2 (g) The partial pressure of CO 2 (g) in a 0.500 dm 3 sample of air is 5.37 kPa at 20 ° C. (i) Calculate the amount, in moles, of CO 2 (g) present in the sample of air at 20 ° C. amount of CO 2 (g) = .............................. mol [2] (ii) Calculate the mass of Na 2 O 2 (s) that would react fully with the amount of CO 2 (g) calculated in (i) . mass of Na 2 O 2 (s) = .............................. g [1] (iii) The peroxide ion, O 2 2– , has a single covalent bond between the two oxygen atoms. Each oxygen atom carries a negative charge.
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  • Fall '19
  • UCLES

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