ALS11A - Section 11 The d-Block Elements Suggested...

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Unformatted text preview: Section 11/ The d-Block Elements / Suggested solutions / SKH Bishop Baker Secondary School AL Chemistry Section 11 The d-Block Elements 80 IA Q.4 (c) (i) Oxidation number of Ru = +3 or III; coordination no. = 6 [ ½ + ½ ] (ii) Oxidation number of Ca = +2 or II; coordination no. = 6 [ ½ + ½ ] 80 IB Q.5 (a) (i) C, B, D, A (or name in the same order, i.e. light source, filter, sample tube, photoelectric cell / micrometer OR can be given in the reverse order A, D, B, C .[1 or 0] (ii) To select wavelengths (which are absorbed by the solution), monochromatic, one type of colour, one frequency. [1 or 0] (iii) (I) By completing the graph, 2 straight lines intersect, which gives maximum intensity when approximately 3.4 cm 3 of CuSO 4 is mixed with approximately 6.6 cm 3 of ethane-1,2-diamine. [ ½ ] No. of moles of ethane-1,2-diamine which gives a maximum intensity when mixed with one mole of CuSO 4 = 4 . 3 6 . 6 = 2. Thus x = 2. [ ½ ] OR if the student just gives the answer x = 2, gives the full marks. (II) Bonded through the nitrogen atoms [1] Each nitrogen atom as a lone pair of electron available for donation to the Cu 2+ ion. [1] 80 IIB Q.10 (a) Two ligands n d ( n+1 )s ( n+1 )p ↑↓ ↑↓ Four ligands n d ( n+1 )s ( n+1 )p ↑↓ ↑↓ ↑↓ ↑↓ [1] for correct hybridization ; [1] for correct representation ↑↓ ↑↓ ↑↓ ↑↓ Six ligands n d ( n+1 )s ( n+1 )p ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ Note : If only sp, sp 3 , dsp 2 , d 2 sp 3 are given grouping the appropriate boxes together, each hybridization gains only [1]. Arrows are not but if they are drawn., they should be drawn correctly, otherwise, [1] is deducted. (b) (i) is an electrolyte [ ½ ] (ii) is not [ ½ ] because [M IV en 2 Cl 4 ] comprises a central metal ion complexed with 2 en and 2 Cl- to give [M IV en 2 Cl 2 ] 2+ only [1] (c)stereoisomers [1] (or isomers with explanation) Two forms of complexes with the composition [MA 2 B 4 ] n+ arise [2] because of the possibility of the ligand being located either together or separated in the octahedral complex. [2] 81 IB Q.5 (d) (i) Excitation of electrons between two d-orbitals having small difference in energy 1 sp sp 3 dsp 2 d 2 sp 3 Section 11/ The d-Block Elements / Suggested solutions / brought about by absorption of visible light . [1] (ii) Existence of unpaired electrons in the orbitals of transition metal ions. [1] 81 IIB Q.6 (a) (i) 2CrO 4 2- (aq) + 2H 3 O + (aq) → Cr 2 O 7 2- (aq) + 3H 2 O(l) [1] (iii) Cu 2+ (aq) + 2I- (aq) → CuI(s) + ½ I 2 (aq) [1] (c) MnO 4- + 8H + + 5e- → Mn 2+ + 4H 2 O [1] 81 IIB Q.9 (a) N C Cl . 14 2 . 25 = 1.8 . 12 4 . 5 = 0.45 5 . 35 . 167 = 0.45 [2] N : C : Cl = 4 : 1 : 1 or NH 3 : CO 3 2- : Cl- = 4 : 1 : 1 [1] Possible molecular formula (because of monomer) is Co(NH 3 ) 4 CO 3 Cl [1] Check : (on any one of N, C or Cl) C% = 12.0/222.4 x 100% = 5.40 % [1] Structure : (b) CoCl 2 ....
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ALS11A - Section 11 The d-Block Elements Suggested...

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