nacl find le f
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Welcome and thanks for visiting. Module 3 Practical: Structured Questions 2002-7. NaCl Find LE f. F Scullion. JustChemy.Com. 2004/P1. 2004/P2. 2005/P1. 2005/P2. Full explanation provided on the next slide. - PowerPoint PPT PresentationTRANSCRIPT
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NaClFind LEf
Module 3
Practical: Structured Questions2002-7
Welcome and thanks for visiting.
F Scullion. JustChemy.Com
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2004/P1
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Full explanation provided on the next slide
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Oxidising ability of Concentrated Sulphuric Acid.Its reactions with halide ions in aqueous solution during the formation of the Hydrogen Halides.[CARE: CARRY OUT ALL OF THESE IN A FUME CUPBOARD WITH GREAT CARE]
2a) KBr(s) + H2SO4(l) KHSO4(aq) + HBr(g)
However, the concentrated sulphuric acid will oxidise some of the HBr as follows:
-1 0
2b) 2HBr + H2SO4 Br2 + SO2 + 2H2O
Therefore, one will observe a Reddish Vapour due to some bromine being present. The SO2 is and acidic gas. It is also a reducing agent and will, for example, decolourise purple potassium permanganate solution
An increase in O.N.
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SUMMARY for all of the Halides.Oxidising ability of Concentrated Sulphuric Acid.Its reactions with halide ions in aqueous solution during the formation of the Hydrogen Halides.[CARE: CARRY OUT ALL OF THESE IN A FUME CUPBOARD WITH GREAT CARE]1) NaCl(s) + H2SO4(l) = NaHSO4(aq) + HCl(g)The concentrated sulphuric acid will not oxidise HCl2a) KBr(s) + H2SO4(l) = KHSO4(aq) + HBr(g)The concentrated sulphuric acid will oxidise some of the HBr as follows: 2b) 2HBr + H2SO4 + Br2 + SO2 + 2H2OTherefore, one will observe a Reddish Vapour due to some bromine being present. 3a) KI(s) + H2SO4(l) à KHSO4 + HI(g)The concentrated sulphuric acid will oxidise some of the HI as follows: 3b) H2SO4(l) + 2HI(g) + SO2 + I2 + 2H20 3c) H2SO4(l) + 6HI(g) + S + 3I2 + 4 H20 3d) H2SO4(l) + 8HI(g) + H2S + 4I2 + 4 H20 During the reaction one will observe: -
· Violet Iodine Vapour being evolved,· The violet vapour cooling and subliming to form dark solid iodine,· A smell of rotten eggs (H2S)· Some free yellow sulphur· Some HI(g) which could be identified in the way one shows the presence of HCl. Use concentrated NH3 solution
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Ethanol Hexane Cyclohexane Cyclohexene
Increasing carbon/hydrogen ratio = Increasing smoke and soot
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To make the Bunsen valve in this case, use a stopper with two holes. Place a glass tube through the second hole. Then put a piece of rubber tubing on the end of the glass tubing, cut a vertical slit in the rubber tubing and put a glass plug in there.
This valve acts in one direction,It prevents access of air while release of the gas from the flask is permitted
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is primary, secondary or tertiary
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89More detail provided on the next two slides
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Oxidising ability of Concentrated Sulphuric Acid.Its reactions with halide ions in aqueous solution during the formation of the Hydrogen Halides.[CARE: CARRY OUT ALL OF THESE IN A FUME CUPBOARD WITH GREAT CARE]
2a) KBr(s) + H2SO4(l) KHSO4(aq) + HBr(g)
However, the concentrated sulphuric acid will oxidise some of the HBr as follows:
-1 0
2b) 2HBr + H2SO4 Br2 + SO2 + 2H2O
Therefore, one will observe a Reddish Vapour due to some bromine being present. The SO2 is and acidic gas. It is also a reducing agent and will, for example, decolourise purple potassium permanganate solution
An increase in O.N.
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SUMMARY for all of the Halides.Oxidising ability of Concentrated Sulphuric Acid.Its reactions with halide ions in aqueous solution during the formation of the Hydrogen Halides.[CARE: CARRY OUT ALL OF THESE IN A FUME CUPBOARD WITH GREAT CARE]1) NaCl(s) + H2SO4(l) = NaHSO4(aq) + HCl(g)The concentrated sulphuric acid will not oxidise HCl2a) KBr(s) + H2SO4(l) = KHSO4(aq) + HBr(g)The concentrated sulphuric acid will oxidise some of the HBr as follows: 2b) 2HBr + H2SO4 + Br2 + SO2 + 2H2OTherefore, one will observe a Reddish Vapour due to some bromine being present. 3a) KI(s) + H2SO4(l) KHSO4 + HI(g)The concentrated sulphuric acid will oxidise some of the HI as follows: 3b) H2SO4(l) + 2HI(g) SO2 + I2 + 2H20 3c) H2SO4(l) + 6HI(g) S + 3I2 + 4 H20 3d) H2SO4(l) + 8HI(g) H2S + 4I2 + 4 H20 During the reaction one will observe: -
· Violet Iodine Vapour being evolved,· The violet vapour cooling and subliming to form dark solid iodine,· A smell of rotten eggs (H2S)· Some free yellow sulphur· Some HI(g) which could be identified in the way one shows the presence of HCl. Use concentrated NH3 solution
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Please see the next slide
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That’s it. Thanks for listening.
Do consider using the other three parts in this Series: -
Observation & Deduction Planning Titrations
Good luck with your Practical Examination.
F Scullion, JustChemy.Com