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ThioSulphate and Sulphate: Chemical Properties and Reactions

Explore the analytical chemistry aspects of ThioSulphate and Sulphate, including reactions, properties, and tests. Learn about reducing properties and wet reactions with BaCl2, AgNO3, Pb(Ac)2, FeCl3, and more.

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ThioSulphate and Sulphate: Chemical Properties and Reactions

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  1. By PH Mohamed Hamdy I am proud to be pharmacist

  2. Analytical chemistrysecond part of lecture (2)lecturer : Dr.Magda

  3. In this lecture we take about :(3)ThioSulphate (S2O3ˉˉ):--Parent acid :-H2S2O3 Thiosulphuric acid-DryTest :-S2O3ˉˉ + 2H* → H2S2O3 ↓∆ H2O+SO2↑+S˚↓Thiosulphuric acid easily decomposed to give colloidal sulphur with yellow colour thiosulphuric acid has Reducing Properties

  4. -Wet Reactions :- .Reaction with BaCl2 :-It gives No ppt in Dil.solution But ppt is formed in conc.solutionBa** + conc.S2O3 → BaS2O3↓ ↓Boil BaSO4↓ ( white ppt )

  5. .Reaction with AgNO3:-2Ag* + S2O3ˉˉ → Ag2S2O3 ↓White ppt ↓H2O H2SO4 + Ag2S↓↓ (Black ppt)It gives white ppt of (Ag2S2O3) silver thio sulphate which changes its colour on standing fromwhite → yellow →Brown → Black

  6. .Reaction with Pb(Ac)2:-Pb** + S2O3ˉˉ→PbS2O3 ↓ ↓Boil PbS ↓↓(Black ppt.It gives white ppt of lead thiosulphate (PbS2O3) which is soluble in cold.HNO3.On Boiling give black ppt of (PbS)

  7. .Reaction with FeCl3:-Fe*** + 2S2O3ˉˉ → [Fe(S2O3)2]ˉ (purple complex) ↓∆ 2Fe** + S4O6ˉˉ .It gives purple colour of [Fe(S2O3)2]ˉcomplex ferric thiosulphate.on Boiling purple colour Disappear and formation of Fe** and tetrathionate S4O6ˉˉ

  8. Q:prove that Sˉˉ,SO3ˉˉ,S2O3ˉˉHave Reducing properties ???A-Reaction with I2(iodine):- Sˉˉ SO3ˉˉ S2O3ˉˉ ↓I2/H* ↓I2/H* ↓I2/H* 2Iˉ+S˚ 2Iˉ+SO4ˉˉ S˚+2Iˉ+S4O6ˉˉBy addition of I2 in acidic media (Brown solution ) to Sˉˉ,SO3ˉˉ,S2O3ˉˉleads to discolouration of brown colour of I2 solution and give colours solution

  9. You also can prove that by B-Reaction with K2Cr2O7 :- C-Reaction with KMnO4 (pot.permenganate) Dr.Magda said that you can use A or B or C to prove thatbut you should also know B and Cso depend on your self to get them 

  10. (4)Sulphate SO4ˉˉ :--Parent Acid: H2SO4 Sulphuric Acid-Dry Test:- SO4ˉˉ + 2H* → -ve ( means no rection)

  11. Important notes :.General properties of Sulphuric Acid1- one of the strongest acids 2-Ionizes in dilute solution in 2 stepsH2SO4 ↔ H* + H2SO4ˉH2SO4ˉ↔ H* + SO4ˉˉ3-It has Dehydrating properties :-concerated H2SO4 has great tendency (ميل او قابلية) to combine withwater to form stable Hydrates (H2SO4.H2O)

  12. H2SO4 ALSO :can extract H2O from certain substances C2H5-OH + H2SO4 →C2H4+H2SO4.H2O (Hydrated sulphuric a)and cause charring to sugars due to removing water from them

  13. 4-H2SO4 Has Oxidising properties :It is moderately oxidising agent when heated with most reducing agents H2SO4(▲)→H2O + SO2+[O]H2SO4+8HI→H2S + 4I2 +4H2OSOOOOOO NEVER SAY Sulphuric acid act as reducing agentit is oxidising agent (ok?????)

  14. -Wet Reactions:-.Reaction with BaCl2:Ba** + SO4ˉˉ→ BaSO4↓(white ppt)Note that BaSO4 is insoluble in dil.HCl even upon boiling .Reaction with AgNO3:2Ag* + SO4ˉˉ(conc.)→Ag2SO4 ↓ (white ppt)

  15. .Reactions with Pb(Ac)2:Pb** + SO4ˉˉ→ PbSO4↓↓white ppt PbSO4 + 3OHˉ→HPbO2ˉ+H2O+SO4ˉˉNote that PbSO4 ( lead sulphate) is insoluble in cold.dil.mineral acids but sol.in KIana Ammonium Acetate solution

  16. .Reaction with FeCl3:(-ve) No reactionthat was about SO4ˉˉLet’s see what next

  17. (5)PerSulphate S2O8ˉˉ:All Reactions of S2O8ˉˉon cold is –ve (negative) No reaction occur .Dry Test:S2O8ˉˉ + H2O (▲)→SO4ˉˉ +H2SO4+[O] ↓HCl ↑ Cl2

  18. -Wet Reactions:.Reaction of BaCl2:S2O8ˉˉ+H2O(▲)→SO4ˉˉ ↓Ba** BaSO4↓white ppt .Reactions with AgNO3:S2O8ˉˉ+2H2O+2Ag*(▲)→Ag2O2↓+2H2SO4 (black ppt)

  19. .Reaction with Pb(Ac)2:No reaction on cold, on boiling Brown pt of Hydrated peroxide appear.Reaction with FeCl3:NO REACTION

  20. SPECIAL TEST : ( SO IMPORTANT)1-For Sˉˉ:a-Cadmium carbonateTest:Cd** + Sˉˉ→CdS ↓yellow ppt sulphide solution is shaken with CdCO3 →yellow ppt of CdS producedb-Sodium Nitro Prusside Test:Sˉˉ+[Fe(CN)5NO]ˉˉ→[Fe(CN)5NOS]ˉˉˉˉ (purple colour)

  21. 2-for Sulphite SO3ˉˉ:Zinc Nitro prusside Test:ZnSO4+K4[Fe(CN)6]+ Sod.nitro prusside + SO3ˉˉ→Red colour ofZn[Fe(CN)5NO]+ moist SO2 →Na5[Fe(CN)5SO3] (red complex)

  22. 3-For ThioSulphate S2O3ˉˉ:Thiocyanate test:S2O3ˉˉ+CNˉ(boiling alkaline) → SCNˉ+SO3ˉˉ H* ↓Fe*** Fe(SCN)3 or [Fe(SCN)]** (red blood colour)

  23. 4-For sulphate SO4ˉˉ:Hepar’s Test:MSO4 + Na2CO3(fusion)→Na2SO4+ MCO3 ↓carbon Na2S+4CO↑ ↓H2O Ag2S ←Ag*+H2S (black ppt)SO4ˉˉis reduced by (C) to Sˉˉ by heating on piece of charcoal in prescence of Na2CO3

  24. 5-For persulphate S2O8ˉˉ:Depend on their oxidising properties1- S2O8ˉˉ+ 2Iˉ→I2(brow) + SO4ˉˉ ↓starch blue2- 5S2O8ˉˉ+2Mn**(manganous)+ 8H*→2MnO4+ 10SO4ˉˉ+6H* (pink colour)

  25. Analysis of mixtures of Sˉˉ,SO3ˉˉ,S2O3ˉˉ,SO4ˉˉ

  26. YOU should look on these pages in the book 21 , 22,23

  27. المصادر الكتاب – ورق الشروقالحمدلله الذى هدانا الى هذا و ما كنا لنهتدى لولا أن هدانا الله و ان قدر الله لك ان تستفيد بهذا و لو معلومة واحدة فاسالك بها دعوة بظهر الغيب و أخــــــــــــــــــــــيــــرا

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