Question

a. With the help of a Lewis diagram, predict the molecular geometry of the following compounds. a. SbF5 b. PF3 C. COCI2 (9 marks) b. Hydrogen peroxide is a powerful oxidizing agent; it is used in concentrated solution in rocket fuel, but in dilute solution in hair bleach. An aqueous solution of H2O2 is 30.0% by mass and has a density of 1.11 g/mL. Calculate a. molality b. mole fraction of H202 c. molarity (7 marks) c. Calculate the vapor pressure lowering, AP, when 10.0 mL of glycerol (C3H803) is added to 500.0 mL of water at 50.0°C. At this temperature, the vapor pressure of pure water it 92.5 torr and its density is 0.988 g/mL. The density of glycerol is 1.26 g/mL. (6 marks) d. Arrange the following compounds in each of the following series in order of increasing acid strength. Explain your answers. i) H20 and H2S ii) HCl and H2S (3 marks)

Answer 1

a) SbFs Valence ē in Sb = 5 valence é in F - 7 Total valence é in SbFg=5+ 5x7 = 40 € Lewis structure * Note: Molecular geometing consider only bond pals electron (O) Hybridization = sp²d (50) Molecular geometry Trigonal bypiramidal 6 PE3 valence è in p=5 Valence éin F = 7 Total valence é in PE = 5+7X3= 26 € Lewis structurs : Follo F: ol SP: hybridization = sp3 (30+ I lone pair) Pyramidar Molecular geometry

Сосі, C = 4 Valence é in valence è in valence é in 0 = 6 C1=7 Total valence in colly = 4+6+782 = 24€ Lewis Structen : و : 01 10: Hybridization = sp² (30) Trigonas planar =O: Molecular geometry Ans b Sbfs Trignal bipyramidal PF3 Pyramidal Colla > Toignal planar, G Given Mass y Of H2O2 = 30% 30 100 It means 3og of H2O2 Is present in toog of solution Mass of H₂O2 = 30 g Mass of solution 100g @ Molality : gt is defined as the moles of solute dissolve per kg of solvent molality - moles of salute (122) Mass of salvent in nkg

moles of 402 : we mass know moles molar mais 30 g mass of H₂O2= Molas Mass ң,». = 2XIT 2X16 349/mor = 34 g/mon moles of H₂O2 30g 0.882 mor ✓ 34 almu Mass of salvent! we know Mass of solution = Mass of Salute + Mass of solvent > 100 Dog 3og + mass of Solvent .., mass of solvent = 100-30= 70 70g = = 70 looo kg = 0.07 kg Put in 0.88 2 mar Molality 12.6 mol 0.07kg on kg 12.6min Ans : molality 12.6m 6 mole fraction : It is the ratio of of component to moles of all One the number of moles total number of component the the moles of H₂O2 mole fraction of H2O2 = moles of H₂O2 t moles of water (salvent)

we have moles of H2)2 = 0.882 more moles of H₂O : mass of H₂o (solvent) 70 g glna molar mars = 18 i moles of water = 70 g 18 g/muse 3.89 mol v = Put in ② 0.882 mole fraction of 0.185 42 0.812 +389 And mole fraction of H2O2 = 0.185 molarity : moles of at is defined as the per like of solution solute dissolve ie: Molarity moles of solute (422) volume of solution in he have moles of solute = 0,882 mor volume of solution we know Mass Density volume Given Density of solution = 1.11g/m Mass of solution - - 100g U lilly loog volume of solution mi

Volume of salution : mL = 90.09 mL = 1.1 90.09 = 0.096 1000 volume of Solution 0.096 ✓ Ret in ③ molarity = 0.882 Moi 0.09L 9.79 muez' 9.79 M V Angi Molarity = 9.79 M. It is a colligative © Relative lowering of vapor Pressure : property and is given by the expression as X AP po Salute 0 Where AP vapor pressure lowering pay vapor pressure of pure Salvent (water) Usalute > mole fraction of salute. ( glycerol) To find a Salute (glycerol) 1 moles of glycerol H glycerol moles of glycent t moles of water First we find the mass of glycerol and mass of water : Mass of glycerol Mass Density = volume 1.26 alph man of glycesor loghe

mass of glyceart = 1.26x10 g 12.6 g Mass of water : 0,988 Hofm - Mass of water ooma 500 mass of water = 0.9888 500 g = 494 gr moles of Glycerol : mass moles a molar mass moles of glucose 12.69 92 g/mol 0.137 mal v moles of water ! 494 g 189/me 27-44 mor moles of water = Substitute the value of moles of glucose and moles of in equ ③ water 0.137 x 0.00497 s Glycerol 0.1377 27.44 " X 0.00497 Glycerol Criven pº Substitute the value of x and po in equ 92.5 torg 0.00497 AP 92.5 toor

AP=0.004978 92.5 toon = 0.46 tors Ans: AP = 0.46 toor (1) H₂O and H₂S S is larger in size than o bond length is longer Therefore the S-H 0-H bond So H₂S can and weaker than the easily give it tons in solution. is stronger acid Therefore H₂S than H₂O Ang : H₂S کا than Нc| (ii) HCl and H₂S: stronger acid H₂ S. This iį because cl is more electronegative than s. Therefore it easily furnish it low in aqueous salution, Any: Нc|
Answer question