February/March 2026 Paper 22

2026 · 4 questions · 39 parts · 60 marks

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4(a)(i)Acid Base Properties ReactionsEasy1 mark

Cyanoethanoic acid, CH

_{2}

(CN)COOH, is a weak organic acid.

At room temperature, CH

_{2}

(CN)COOH undergoes an acid–base reaction with NaOH(aq).

Define weak acid.

4(a)(ii)Ph Curves IndicatorsHard3 marks

Sketch the pH titration curve on Figure 4.1 for the reaction of:

25.00 cm $^{3}$ of 0.10 mol dm $^{- 3}$ CH $_{2}$ (CN)COOH(aq) and
0.10 mol dm $^{- 3}$ NaOH(aq), added to excess.

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4(a)(iii)Acid Base Properties ReactionsEasy1 mark

Write the overall ionic equation for the neutralisation of CH

_{2}

(CN)COOH(aq) by NaOH(aq) in 4(a)(ii). Include state symbols.

Answer

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4(a)(iv)Amines Nitriles Azo DyesMedium1 mark

Suggest the formula of the organic product when CH

_{2}

(CN)COOH(aq) is heated under reflux with NaOH(aq).

Answer

4(b)Intermolecular Forces Physical PropertiesHard3 marks

_{2}

(CN)COOH is very soluble in water because it can form hydrogen bonds with water.

Complete Figure 4.2 to show one hydrogen bond between a molecule of CH

_{2}

(CN)COOH and a molecule of H

_{2}

O. Label the hydrogen bond clearly, and show any relevant partial charges and lone pairs of electrons.

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4(c)(i)HalogenoalkanesMedium2 marks

Figure 4.3 shows a synthesis of CH

_{2}

(CN)COOH.

The reaction mechanism of the synthesis in Figure 4.3 has a single step. Complete Figure 4.3 to show this mechanism. Include lone pairs, charges, dipoles and curly arrows as appropriate.

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4(c)(ii)HalogenoalkanesEasy1 mark

Identify the nucleophile in Figure 4.3.

4(c)(iii)HalogenoalkanesEasy1 mark

Identify the mechanism of the reaction in Figure 4.3.

4(d)(i)Carboxylic Acids EstersEasy1 mark

Figure 4.4 describes a sequence of reactions, starting with CH

_{2}

(CN)COOH, to form E.

Figure 4.4, a two-step reaction sequence starting from cyanoethanoic acid, NC-CH$_{2}$-COOH: step 1, with C$_{2}$H$_{5}$OH and H$^{+}$, gives the ethyl ester NC-CH$_{2}$-COOC$_{2}$H$_{5}$; step 2, with HCHO, gives compound E, CH$_{2}$=C(CN)-COOC$_{2}$H$_{5}$, drawn with the CN group branching down from the alkene carbon and the ester group OC$_{2}$H$_{5}$ to the right.

Identify the type of reaction that occurs in step 1.

4(d)(ii)Organic Nomenclature FormulaeEasy1 mark

Name HCHO, the reactant used in step 2.

4(d)(iii)Organic Nomenclature FormulaeMedium1 mark

Deduce the molecular formula of E.

Answer

4(d)(iv)Addition PolymersMedium1 mark

E can be polymerised to form F. Draw the structure of one repeat unit of polymer F.

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4(d)(v)Mass Spectrometry Infrared SpectroscopyMedium2 marks

Table 4.1

bond	functional groups containing the bond	characteristic infrared absorption range (in wavenumbers) / cm $^{- 1}$
C–O	hydroxy, ester	1040–1300
$C = C$	aromatic compound, alkene	1500–1680
$C = O$	amide; carbonyl, carboxyl; ester	1640–1690; 1670–1740; 1710–1750
C≡N	nitrile	2200–2250
C–H	alkane	2850–2950
N–H	amine, amide	3300–3500
O–H	carboxyl; hydroxy	2500–3000; 3200–3650

Figure 4.5 shows the infrared spectrum of E.

Using the information given in Table 4.1, identify with a cross (

\times

) on Figure 4.5 an absorption that can be used to monitor the progress of the polymerisation of E to form F. Explain your answer with reference to the relevant bond.

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