By which of the following reagents, formic acid and formaldehyde can be distinguished ?
(A) Benedict’s solution
(B) Tollen’s reagent
(C) Fehling’s solution
(D) NaHCO3
1 Answers
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Upon passing `0.01` moles `HCl` gas through `100mL` of `0.05M` Formic acid solution `(K_(a)=1.8xx10^(-4))` determine change in `pH` of solution and `[
Initial `pH:alpha=sqrt((K_(a))/(C))=0.06(lt0.1)` So `[H^(+)]=Calpha=0.06xx0.05=0.003M` `:.pH=2.52` final `pH=-log(0.01)/(0.1)=1` :.Change =`1-2.52=-1.52`. Now `K_(a)=([H^(+)][HCOO^(-)])/([HCOOH])rArr 1.8xx10^(-4)=(0.1xx[HCOO^(-)])/(0.05)` `rArr [HCOOH^(-)]=9xx10^(-5)M`
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The self ionisation constant for pure formic acid `K=[HCOOH_(2)^(+)][HCOO^(-)]` has been estimated as `10^(-6)` at room temperature .The density of fo
Given density of formic acid =`1.15g//cm^(3)` :.Weight of formic acid in `1` litre solution =`1.15xx10^(3)g` thus `[HCOOH]=(1.15xx10^(3))/(46)=25M` since in case of auto ionisation `[HCOOH_(2)^(+)]=[HCOO^(-)]` and `[HCOO^(-)][HCOOH_(2)^(+)]=10^(-6)rArr [HCOO^(-)]=10^(-3)` Now `%` dissociation...
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Formic acid is obtained when :
Correct Answer - C `underset"Oxalic acid"underset(COOH)overset(COOH)(|)underset"Heat 373 K"overset"Glycerol"to=underset"Formic acid"(HCOOH)+CO_2uarr`
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Compound `I` and `II` can be distinguished by using reagent. `underset("4-Hydroxy-4-methylpent-2-enoic acid")((I))` " " `underset("5-Hydroxypent-2-yno
Correct Answer - C `underset((I))(underset(HOOC)underset(|)(HC)=underset(H)underset(|)(C )-underset(OH)underset(|)overset(CH_(3))overset(|)(C )-CH_(3))` " " `underset((II))(underset(HOOC)underset(|)(C )-=C-CH_(2)-underset(OH)underset(|)(CH_(2)))` `(I)` gives immediate turbidity by Lucas reagent and `(II)` does not give turbidity appriciably.
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The heat of ionisation of formic acid is 1.5 kJ/ mo. 9.2 g formic acid on reaction with 7 g ammonium hydroxide gives 10.8 kJ of heat. Calculate the he
Correct Answer - `2.04kJ//mol`
2 Answers 1 views
List three reagents for converting a carboxylic acid to its acyl chloride. Select the most convenient of the three reagents. Give a reason for the cho
`PCl_(3), SOCl_(2) and PCl_(5), SOCl_(2)` is the best reagent because the products of the reaction besides acyl chloride are `SO_(2)` and HCl which are gases and easily separated
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Pair of molecules which forms strongest intermolecular hydrogen bonds is ……… `(SiH_(4)` and `SiF_(4)`, acetone and `CHCl_(3)`, formic acid and acetic
Correct Answer - `HCOOH` and `CH_(3)COOH`
2 Answers 1 views
Primary amine can be distinguished from a secondary amine using the reagents
Correct Answer - (a,b,c)
2 Answers 1 views
Which of the following compounds is obtained when formic acid is heated with Conc. H2SO4 ?
Correct answer is (D) CO
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What volume (inml) of `0.10 M` sodium formate solution should be added to `50 ml` of `0.05M` formic acid to produce a buffer solution of `pH4. [pK_(a)
Correct Answer - `0050`
2 Answers 1 views