A LEVEL 化学 A2-Group IV 第四主族元素 (1) worksheet with answers

A2 Chemistry Group IV (1) answer1. Writebalancedequationsforthefollowingreactions.(a) the reactionofgermanium (IV)chloridewithwater GeCl4 + 2H2O GeO2 + 4HCl(b) the thermaldecompositionoflead (IV)oxide 2PbO2 2PbO + O2 (c) the reactionofgermanium (II)oxidewithhydrochloricacid GeO + 2HCl GeCl2 + H2O (d)the reactionoflead(II)oxidewithaqueoushydroxideionstoform theplumbate(II)ionPbO + 2OH PbO22 + H2O (e) the reactionofcarbondioxidewithwaterto formthehydrogencarbonateion CO2 + H2O HCO3 + H+(f) the reactionofcarbondioxidewithaqueoushydroxideions CO2 + 2OH CO32 + H2O (g) the reactionofsilicon (IV)oxidewithaqueoussodiumhydroxide SiO2 + 2NaOH Na2SiO3 + H2O(h) the disproportionation of germanium (II) oxide on heating to form germanium(IV) oxide and germanium 2GeO GeO2 + Ge2. The melting points of the Group IV elements are given in the table.ElementMelting point / CCarbon (diamond)3550Silicon 1410Germanium937Tin232Lead327(a) Describe and explain how the trend in melting point is related to the structure and bonding in these elements. Melting point decreases down the groupDiamond, Si and Ge have giant covalent structures; strength of bonds in order of C-C Si-Si Ge-Ge;Sn and Pb have giant metallic structures; but metallic bonding is not very strong because of the large ions(b) Carbon dioxide is a gas but tin (VI) oxide is a solid. Explain this difference in terms of structure and bonding.CO2 has simple molecular structure;Weak V.D.W. forces between molecules;SnO2 has a giant covalent structure;Requires a lot of energy to break the strong bonds(c) Explain in terms of structure and bonding why silicon (IV) oxide is used as a lining in furnaces. It has a giant covalent structure; It takes a lot of energy to break strong covalent bonds; 3. Describe, and explain, the differences in electrical conductivity between carbon (as diamond and as graphite), silicon, germanium, tin and lead.Diamond is insulator because all the electrons are involved in covalent bonds.Graphite is conductor because some of its electrons are delocalized.Si and Ge are semi-conductors because some electrons are free to move.Sn and Pb are good conductors because they have metallic structure with delocalized electrons.4. All the Group IV elements form chlorides with the formula MCl4.(a) Describe the bonding in, and the shape of, these chlorides.(i) bonding covalent(ii) shape tetrahedralThe boiling point of lead (IV) chloride cannot be measured directly because it decomposes on heating. The following table lists the boiling points of three Group IV chlorides.(b) (i) Plot these data on the following axes and extrapolate your graph to predict what the boiling point of PbCl4 would be if it did not decompose.(ii) Suggest why the boiling points vary in this way.b. p. increases due to larger van der Waals(c) SiCl4 reacts vigorously with water whereas CCl4 is inert.(i) Suggest a reason for this difference in reactivity.Si has empty low-lying d-orbitals(ii) Write an equation for the reaction between SiCl4 and water.SiCl4 + 2H2O SiO2 + 4HCl(iii) Suggest, with a reason, whether you would expect GeCl4 to react with water.Yes, because Ge also has empty low-lying d-orbitals(d) SiCl4 is used to make high-purity silicon for the semiconductor industry. After it has been purified by several fractional distillations, it is reduced to silicon by heating with pure zinc.(i) Suggest an equation for the reduction of SiCl4 by zinc.SiCl4 + 2Zn Si + 2ZnCl2(ii) Use your equation to