Chemistry WCH16/01 October 2020
Edexcel
International AS/A Level
Chemistry (WCH)
Oct
2020
2. chromate–dichromate equilibrium—CrO₄²⁻ yellow to Cr₂O₇²⁻ orange, Cr³⁺ green from ethanol reduction, ethanol oxidation to ethanal
3. structural isomers—C₄H₈O₂ compounds, ester vs acid, mass spec m/z 46 for ethanol, 43 for CH₃CO⁺ ion, acid–base reactions with NaHCO₃
4. proton NMR—chemical shifts, relative area ratios (1:6:1), splitting patterns to deduce structure of butanoic acid
5. rate equation determination—BrO₃⁻, Br⁻, H⁺ reaction, methyl red bleaching, use of reciprocal time (1/t) as rate proxy, first-order confirmation
6. aspirin synthesis—2-hydroxybenzoic acid with ethanoic anhydride, use of conc. H₂SO₄ catalyst, reflux apparatus corrections, excess reagent calculation
7. purification techniques—cooling, recrystallisation, Buchner filtration benefits, purity test via melting point comparison to pure aspirin reference
معلم موافق رایگان بودن است.
1. transition metal complex identification—Cu(OH)₂ formation, [Cu(NH₃)₄(H₂O)₂]²⁺ complex, thermal decomposition to black CuO, yellow [CuCl₄]²⁻ formation2. chromate–dichromate equilibrium—CrO₄²⁻ yellow to Cr₂O₇²⁻ orange, Cr³⁺ green from ethanol reduction, ethanol oxidation to ethanal
3. structural isomers—C₄H₈O₂ compounds, ester vs acid, mass spec m/z 46 for ethanol, 43 for CH₃CO⁺ ion, acid–base reactions with NaHCO₃
4. proton NMR—chemical shifts, relative area ratios (1:6:1), splitting patterns to deduce structure of butanoic acid
5. rate equation determination—BrO₃⁻, Br⁻, H⁺ reaction, methyl red bleaching, use of reciprocal time (1/t) as rate proxy, first-order confirmation
6. aspirin synthesis—2-hydroxybenzoic acid with ethanoic anhydride, use of conc. H₂SO₄ catalyst, reflux apparatus corrections, excess reagent calculation
7. purification techniques—cooling, recrystallisation, Buchner filtration benefits, purity test via melting point comparison to pure aspirin reference
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