(A) Write chemical equations for the reactions that occur when NaCN is dissolved in water and when Al(NO₃)₃ is dissolved in water. Then, use data from Appendix D to explain why a precipitate of Al(OH)₃ forms when equal volumes of 1.0 M aqueous solutions of NaCN and Al(NO₃)₃ are mixed.

(B) The compound BeCl₂ · 4 H₂O cannot be dehydrated by heating and it dissolves in water to give an acidic solution. Conversely, CaCl₂ · 6 H₂O can be dehydrated by heating and it dissolves in water to give a solution with neutral pH. Explain these observations and write chemical equations for the reactions that occur, if any, when the salts are heated and when they are dissolved in water.

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TABLE D.1 Ground-State Electron Configurations Element Configuration Z Z 1 2 3 4 5 6 7 8 9 HIG&LUZONSUZ SE> 0 ≤ 2 3 2 3 5 3 3 2 2 5 2 He 10 11 12 13 14 15 16 17 18 19 20 21 Sc 22 23 24 25 Mn Mg 26 27 28 Ni 29 30 Zn 31 32 33 34 35 36 Ga Ge 1s¹ 1s² [He] 2s¹ [He] 2s2 [He] 2s²2p¹ [He] 2s²2p² [He] 2s²2p³ [He] 2s22p4 [He] 2s²2p5 [He] 2s²2p6 [Ne] 3s¹ [Ne] 3s2 [Ne] 3s 3p¹ [Ne] 3s23p² [Ne] 3s²3p³ [Ne] 3s23p4 [Ne] 3s²3p5 [Ne] 3s23p6 [Ar] 4s¹ [Ar] 4s² [Ar] 3d¹4s² [Ar] 3d²4s² [Ar] 3d³4s² [Ar]3d54s¹ [Ar] 3d³4s² [Ar] 3d64s² [Ar] 3d²4s² Element 37 Rb 38 Sr 39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb 52 Te 53 54 55 56 57 58 59 60 61 62 63 64 I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd [Ar]3d845² [Ar] 3d¹04s¹ 67 [Ar] 3d¹04s2 [Ar] 3d¹04s²4p¹ [Ar]3d¹04s²4p² [Ar]3d¹04s²4p³ 69 Tm 68 Er [Ar] 3d¹04s²4p4 70 Yb [Ar] 3d¹04s²4p5 71 Lu [Ar]3d¹04s²4p6 65 Tb 66 Dy Ho Configuration Z [Kr] 5s¹ [Kr] 5s² [Kr] 4d¹5s² [Kr] 4d²5s² [Kr] 4d45s¹ [Kr] 4d55s¹ [Kr] 4d55s² [Kr] 4d75s¹ [Kr] 4d85s1 [Kr] 4d10 [Kr] 4d105s1 [Kr] 4d¹05s² [Kr] 4d¹05s²5p¹ [Kr] 4d¹05s25p² [kr] 4d¹05s²5p³ [kr] 4d¹05s25p4 [Xe] 6s² [Xe] 5d¹6s² [Xe] 4f²6s² [Xe] 4f³6s² [Xe] 4f46s2 [Xe] 4f6s2 [Xe] 4f6s2 [Xe] 4f76s2 [Xe] 4f75d¹6s² [Xe] 4f%s2 [Xe] 4f106s2 [Xe] 4f¹¹6s² NRNKERKR [Xe] 4f126s2 [Xe] 4f136s2 [Xe] 4f146s2 [Xe] 4f¹45d¹6s² 72 Hf 73 Ta W 74 75 Re 76 Os 77 Element 78 79 80 81 82 83 84 85 86 87 Fr [Kr] 4d¹05s²5p5 88 Ra [Kr] 4d¹05s²5p6 89 Ac [Xe] 6s¹ 90 Th 91 92 93 94 95 96 97 98 99 Ir Pt Au Hg TI Pb Bi Po At Rn Pa U Np Pu Am Cm Bk Cf Es 100 Fm 101 Md 102 No 103 Lr 104 Rf 105 Db 106 Sg Configuration [Xe] 4f¹45d²6s² [Xe] 4f145d³6s² [Xe] 4f145d46s2 [Xe] 4f145d56s2 [Xe] 4f145d6s2 [Xe] 4f¹45d²6s² [Xe] 4f¹45dº6s¹ [Xe] 4f145d106s1 [Xe] 4f145d106s2 [Xe] 4f145d6s26p* [Xe] 4f145d106s36p? [Xe] 4f145d16s?6p3 [Xe] 4f145d6s®6p* [Xe] 4f145d16s26p5 [Xe] 4f145d106s26p6 [Rn] 7s¹ [Rn] 7s² [Rn] 6d¹7s² [Rn] 6d²7s² [Rn] 5f26d¹7s² [Rn] 5f³6d¹7s² [Rn] 5f46d¹7s2 [Rn] 5f67s² [Rn] 5f77s² [Rn] 5f76d¹7s² [Rn] 5f97s2 [Rn] 5f107,2 [Rn] 5f117s2 [Rn] 5f¹27s² [Rn] 5f137,2 [Rn] 5f147s2 Rn] 5f¹46d¹7s² [Rn] 5f¹46d²7s² [Rn] 5f¹46d³7s2 [Rn] 5f¹46d47s²