WorksheetsCarboxylic Acids and Derivatives - Past Paper Practice
Total questions: 22
Worksheet time: 2hrs 50mins
This question is about reactions of carboxylic acids and their derivatives.
Molecule A is 4-hydroxy pentanoic acid.
Draw the skeletal formula Molecule A.
Molecule A (4-hydroxy butanoic acid) reacts in two ways in the presence of an acid catalyst.
Reaction 1 is intramolecular, in which one molecule of A forms a cyclic ester B.
Draw the structure of the cyclic ester B.
Molecule A (4-hydroxy pentanoic acid) reacts in two ways in the presence of an acid catalyst.
Reaction 2 is intermolecular, in which a condensation polymer C forms.
Draw the structure of the condensation polymer C, showing two repeat units.
Explain why the entropy change of the system, ΔSsystem , is greater for Reaction 1 than for Reaction 2.
the number of molecules decreases in reaction 2.
there is no change in the number of molecules in reaction 2.
there is no change in the number of molecules in reaction 1.
one molecule of reactant produces two molecules of product in reaction 1.
The molecule shown is a triester used as a food additive. Give the molecular formula of this triester. (1 mark)
C9H14O6
C9H16O6
C10H14O6
C9H14O5
Complete the equation for the alkaline hydrolysis of this triester with excess aqueous sodium hydroxide, showing the structures of the products.
Some reactions of ethanoyl chloride, CH3COCl, are shown. Identify Reagent P, by name or formula.
(a)
Write a balanced equation for Reaction Q. State symbols are not required.
CH3COCl + 2NH3 → CH3CONH2 + NH4Cl
CH3COCl + NH3 → CH3CONH2 + 2HCl
CH3COCl + NH3 → CH3CONH + HCl
CH3COCl + 2NH3 → CH3CONH2 + NH3Cl
Suggest the structural formula of Reagent R.
CH3NH2
CH4S
H2S
CH3SH
Draw the skeletal formula of Reagent S.
This question is about carboxylic acids and their derivatives. Lactic acid, CH3CH(OH)COOH , is produced in muscles as a result of anaerobic respiration.
The structure of lactic acid is shown. Give a reason why lactic acid shows optical isomerism.
It contains two carboxyl groups that can interchange.
It has restricted rotation around C–C single bonds.
It contains a carbon atom bonded to four different groups, making it chiral.
It shows E–Z isomerism due to a C=C bond.
A laboratory sample of lactic acid, CH3CH(OH)COOH , does not rotate the plane of plane‑polarised monochromatic light.
Give a reason for this observation.
It contains only a single enantiomer of lactic acid.
It is a racemic mixture containing equal amounts of both enantiomers.
Plane‑polarised light cannot interact with chiral molecules.
The molecules of lactic acid are planar and therefore achiral.
Give the structure of the organic product formed when lactic acid, CH3CH(OH)COOH , reacts with concentrated phosphoric(V) acid, H3PO4 .
CH2=CHCOOH
CH3CH2COOH
HCOOCH3
A reaction scheme involving butanoic acid is shown.
Identify X, Y and Z by name or formula.
butan-1-ol
Alcohol X
phosphorous (v) chloride (PCl5)
Reagent Y
N-methyl butanamide
Compound Z
The repeat unit of a polyester is shown.
Give the structures of the pair of monomers that could form this polyester.
There are five carboxylic acids with the formula C4H6O2 .
Four are structural isomers.
Name the two structural isomers shown.
But-1-enoic acid
2-methyl propenoic acid
But-3-enoic acid
2-methyl propanoic acid
The third structural isomer of the carboxylic acid with the formula C4H6O2 has two stereoisomers.
Draw these stereoisomers.
Draw the fourth structural isomer of the carboxylic acid with the formula C4H6O2.
Some reactions involving 3-hydroxy-3-methylbutanoic acid, (CH3)2C(OH)CH2COOH, are shown in a scheme.
Give the reagents and conditions for Reaction 1.
Lithium aluminum hydride in dry ether at room temperature
Potassium manganate(VII), sodium hydroxide, room temperature
Excess phosphorus pentachloride at room temperature
Potassium dichromate(VI), sulfuric acid, heat under reflux
Write the correct overall equation for Reaction 2. State symbols are not required.
(CH3)2C(OH)CH2CN + 2H2O + HCl → (CH3)2C(OH)CH2COOH + NH4Cl
(CH3)2C(OH)CH2CN + H2 → (CH3)2C(OH)CH2CH2NH2
(CH3)2C(OH)CH2CN + HCl → (CH3)2C(OH)CH2Cl + HCN
(CH3)2C(OH)CH2CN + NaOH → (CH3)2C(OH)CH2COONa + NH3
Give the structure of the organic product formed in Reaction 3.
Give the structure of the organic product formed in Reaction 4.
