Question
Explain laboratory tests for carboxyl (- COOH) group.
✓
Answer
The presence of $- COOH$ group in carboxylic acids is identified by the following tests :
(1) Litmus test : (valid for water soluble substances)
Aqueous solution of Organic compound containing $- COOH$ group turns blue litmus red which indicates the presence of acidic functional group.
(2) Sodium bicarbonate test: When sodium bicarbonate is added to an organic compound containing $- COOH$ group, a brisk effervescence of carbon dioxide gas is evolved. Water insoluble acid goes in solution and gives precipitate an acidification with cone. $HCl$. This indicates the presence of - $COOH$ group.
(3) Ester test: One drop of concentrated sulfuric acid is added to a mixture of given organic compound containing $- COOH$ group and one $mL$ of ethanol, the reaction mixture is heated for 5 minutes in hot water bath. After this, hot solution is poured in a beaker containing water, fruity smell of ester confirms the presence of carboxylic acid.
(1) Litmus test : (valid for water soluble substances)
Aqueous solution of Organic compound containing $- COOH$ group turns blue litmus red which indicates the presence of acidic functional group.
(2) Sodium bicarbonate test: When sodium bicarbonate is added to an organic compound containing $- COOH$ group, a brisk effervescence of carbon dioxide gas is evolved. Water insoluble acid goes in solution and gives precipitate an acidification with cone. $HCl$. This indicates the presence of - $COOH$ group.
(3) Ester test: One drop of concentrated sulfuric acid is added to a mixture of given organic compound containing $- COOH$ group and one $mL$ of ethanol, the reaction mixture is heated for 5 minutes in hot water bath. After this, hot solution is poured in a beaker containing water, fruity smell of ester confirms the presence of carboxylic acid.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In an experiment, $18.04 g$ of mannitol were dissolved in $100 g$ of water. The vapour pressure of water was lowered by $0.309 mm Hg$ from $17.535 mm Hg$. Calculate the molar mass of mannitol.
→For the reaction,
$
3 I _{(a q)}^{-}+ S _2 O _{8(a q)}^{2-} \longrightarrow I _{3( aq )}^{-}+2 S O _{4( aq )}^{2-}
$
Calculate (a) the rate of formation of $I _3^{-}$,
(b) the rates of consumption of 1 and $S _2 O$ and (c) the overall rate of reaction if the rate of formation of $SO _4^{2-}$ is 0.022 moles $dm ^{-3} sec ^{-1}$.
→$
3 I _{(a q)}^{-}+ S _2 O _{8(a q)}^{2-} \longrightarrow I _{3( aq )}^{-}+2 S O _{4( aq )}^{2-}
$
Calculate (a) the rate of formation of $I _3^{-}$,
(b) the rates of consumption of 1 and $S _2 O$ and (c) the overall rate of reaction if the rate of formation of $SO _4^{2-}$ is 0.022 moles $dm ^{-3} sec ^{-1}$.
Answer the following.Distinguish between rhombic sulfur and monoclinic sulfur.
While considering boiling point elevation and freezing point depression a solution concentration is expressed in molality and not in molarity. Why?
Write Clemmenson's reduction reaction of propanone. Write Fehling solution test for ethanal.
How many moles of electrons are required for the reduction of (i) 3 moles of $Zn ^{2+}$ to $Zn$,
(ii) 1 mol of $Cr ^{3+}$ to $Cr$ ?
How many Faradays of electricity will be required in each case?
→(ii) 1 mol of $Cr ^{3+}$ to $Cr$ ?
How many Faradays of electricity will be required in each case?
The standard enthalpy of combustion of formaldehyde $\Delta_c H^0=-571 kJ$.
How much heat will be evolved in the formation of $22 g$ of $CO _2$ ?
→How much heat will be evolved in the formation of $22 g$ of $CO _2$ ?
Cesium chloride crystallizes in cubic unit cell with Cl -ions at the corners and $Cs +$ ion in the centre of the cube. How many CsCl molecules are there in the unit cell ?
→Explain bond enthalpy in polyatomic molecules.
Write chemical equations involved during manufacture of sulphuric acid by contact process. Write two uses of sulphur dioxide.