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Chemistry: Post your doubts here!

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Can someone please post proper AS practical notes covering all main topics
Please!!!
 
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25 If the starting material is iodoethane, which sequence of reactions will produce propanoic acid as
the main final product in good yield?
A add NaOH(aq), isolate the organic product, add acidified K2Cr2O7 and boil under reflux
B add NaOH(aq), isolate the organic product, add H2SO4(aq) and boil under reflux
C heat with HCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux
D heat with KCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux

the answer is D can anyone explain me why not C
 
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25 If the starting material is iodoethane, which sequence of reactions will produce propanoic acid as
the main final product in good yield?
A add NaOH(aq), isolate the organic product, add acidified K2Cr2O7 and boil under reflux
B add NaOH(aq), isolate the organic product, add H2SO4(aq) and boil under reflux
C heat with HCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux
D heat with KCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux

the answer is D can anyone explain me why not C
HCN is the reagent used to form hydroxynitriles from carbonyl compounds (aledehyde and ketone).
When attempting to form nitriles from HALOGENOLAKES, you should use KCN.
 
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25 If the starting material is iodoethane, which sequence of reactions will produce propanoic acid as
the main final product in good yield?
A add NaOH(aq), isolate the organic product, add acidified K2Cr2O7 and boil under reflux
B add NaOH(aq), isolate the organic product, add H2SO4(aq) and boil under reflux
C heat with HCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux
D heat with KCN in ethanol, isolate the organic product, add H2SO4(aq) and boil under reflux

the answer is D can anyone explain me why not C

It's KCN that undergoes nucleophilic substitution with halogenalkanes to form propanenitrile which is then reduced with H2SO4 to form propanoic acid.
HCN, on the other hand, only reacts with aldehydes and ketones. It's not used in reactions with halogenalkanes
 
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Use of the Data Booklet is relevant to this question.
The compound S2O7 is hydrolysed by water to produce sulfuric acid and oxygen only.
Which volume of oxygen, measured at room temperature and pressure, is evolved when 0.352 g
of S2O7 is hydrolysed?
A 12 cm3 B 24 cm3 C 48 cm3 D 96 cm3
answer is b how
 
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