Chemistry 2021 May/June Paper 42 | Past Paper

Q1(a)

Short Answer 1 mark

An aqueous solution of chromium( III) contains the green [Cr(H complex ion.

Q1(i)

Short Answer 1 mark

Complete the electronic configuration of an isolated, gaseous Cr ion.

Q1(ii)

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Define the term complex ion .

Q1(b)

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[Cr(H

Q1(aq)

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shows some similar chemical properties to [Co(H

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Samples of [Cr(H are reacted separately with either NaOH(aq), H

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, or excess

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Use this information and the Data Booklet to suggest the formula of the chromium species formed. State the type of reaction taking place in each case. reagent added to [Cr(H

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formula of chromium species formed type of reaction NaOH(aq)

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an excess of NH

Q1(c)

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[Cr(H and [CrCCH ] are both complexes of chromium(II) and have different colours. Explain why the colours of these complexes are different.

Q1(d)

Short Answer 1 mark

The structure of [CrCCH ] is shown. Ethanoate ions act as ligands in this complex. The ethanoate ligand, CH , is shown as

Q1(i)

Short Answer 1 mark

Water and ethanoate ions behave as different types of ligand in this complex. Suggest an explanation for this statement.

Q1(ii)

Short Answer 1 mark

Deduce the coordination number of Cr and the geometry around each Cr atom in this structure. coordination number

Q1(iii)

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State the type of bond between the two atoms in the Cr-Cr bond.

Q1(e)

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The [CrCCH ] complex reacts with aqueous acid to form Cr

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ions.

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ions react with O

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under acidic conditions. Cr

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ions are formed. Use the Data Booklet to answer the following questions.

Q1(i)

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Construct an ionic equation for the reaction of Cr

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with O

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under acidic conditions.

Q1(ii)

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Calculate for the reaction in (e)(i). = V [1] [Total: 15]

Q2(a)

Short Answer 1 mark

State and explain the trend observed in the thermal stability of the Group 2 nitrates.

Q2(b)

Short Answer 1 mark

(i) Lead( II) nitrate, Pb(NO , decomposes on heating in a similar manner to the Group 2 nitrates. Write an equation for the decomposition of lead( II) nitrate.

Q2(ii)

Short Answer 1 mark

Suggest how the ease of decomposition of Pb(NO would compare to that of Ba(NO Explain your answer. You may find it useful to refer to the Data Booklet .

Q2(c)

Short Answer 1 mark

(i) Barium ethanedioate, BaC , decomposes on heating to produce barium oxide and a mixture of two different gases. Construct an equation for the decomposition of barium ethanedioate.

Q2(ii)

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An impure sample of BaC acidified MnO

Q2(aq)

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, an excess. A redox reaction takes place and all the BaC reacts. The resulting solution, containing unreacted acidified MnO

Q2(aq)

Structured 4 marks

has been added. 2CO + 2eMnO + 8H + 5e + 4H + e Calculate the percentage by mass of BaC working. : BaC , 225.3] percentage by mass of BaC =

Q2(d)

Short Answer 1 mark

Barium hydroxide, Ba(OH) , is completely dissociated in aqueous solution. Ba(OH) pH = [2] [Total: 12]

Q3(a)

MCQ 1 mark

(i) Define the term standard electrode potential. Three redox systems, A, B and C, are shown. The ligand 1,2-diaminoethane, HNCH is represented by en. A [Ru(H + e [Ru(H B [Ru(NH + e [Ru(NH C [Ru(en) + e [Ru(en) , of three half-cells. The diagrams show the relative potential of each electrode. [Ru(NH [Ru(NH salt bridge [Ru(en) [Ru(en) Pt Pt [Ru(H [Ru(H salt bridge [Ru(en) [Ru(en) Pt Pt

A

[Ru(H

B

[Ru(NH

C

[Ru(en)

Q3(ii)

Short Answer 1 mark

Use this information to complete the table by adding the labels A, B and C to deduce the for the three half-cells. redox system most negative least negative

Q3(iii)

Short Answer 3 marks

The complex [Ru(en) shows stereoisomerism. The ligand en is bidentate. Draw three-dimensional diagrams to show the two isomers of [Ru(en) . Represent the ligand en by using Name the type of stereoisomerism. isomer 1 isomer 2 type of stereoisomerism

Q3(b)

Short Answer 1 mark

(i) An electrochemical cell consists of a Br half-cell and a Ag /Ag half-cell, under standard conditions. Use the Data Booklet to calculate the . Deduce the direction of electron flow in the wire through the voltmeter between these two half-cells. = V

Q3(ii)

Short Answer 1 mark

Water is added to the Ag /Ag half-cell in (b)(i). Suggest the effect of this addition on the E cell less positiveno change more positive Explain your answer.

Q3(c)

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Silver bromide, AgBr, dissolves in an aqueous solution of S ions to form the complex ion [Ag(S . The S ions act as monodentate ligands. equilibrium 1 AgBr(s) + 2S

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[Ag(S

Q3(i)

Short Answer 1 mark

Define the term ligand .

Q3(ii)

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Write an expression for the equilibrium constant, K , for equilibrium 1.

Q3(iii)

Short Answer 1 mark

Some additional data are given about the dissolution of AgBr in S

Q3(aq)

Short Answer 2 marks

equilibrium constant numerical value solubility product, K , of AgBr 5.4 × 10-13 stability constant, K stab , of [Ag(S 2.9 × 10 Use your answer to (c)(ii) and these data to calculate K for equilibrium 1. Include the units for K = units

Q3(d)

Short Answer 1 mark

The numerical values for the stability constants, K stab , of two other silver( I) complexes are given. silver(I) complexnumerical value of K stab [Ag(CN) 5.3 × 10 [Ag(NH 1.6 × 10 An aqueous solution containing Ag is added to a solution containing equal concentrations of

Q3(aq)

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and S

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The mixture is left to reach equilibrium. Deduce the relative concentrations of [Ag(CN) , [Ag(NH and [Ag(S present in the resulting mixture. Explain your answer. highest concentration lowest concentration [Total: 15]

Q4(a)

Short Answer 1 mark

(i) Define the term lattice energy .

Q4(ii)

Short Answer 1 mark

Use the following data to calculate a value for the enthalpy change of solution of copper(

Q4(s)

Short Answer 2 marks

You might find it helpful to construct an energy cycle. enthalpy change of hydration of Cu

Q4(iii)

Short Answer 1 mark

The enthalpy change of hydration of Ca hyd for Ca and Cu

Q4(b)

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(i) Identify the substances formed at the anode and at the cathode during the electrolysis of

Q4(aq)

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at the anode . at the cathode

Q4(l)

Short Answer 2 marks

for 60 minutes. : Ca, 40.1] mass of Ca = g

Q4(c)

Short Answer 2 marks

(i) Explain what is meant by the term entropy of a system. NaCl dissolving in water water solidifying to ice [1] , of positive negative 507510012515025 temperature / C

Q4(d)

MCQ 1 mark

The reaction between A and B is feasible at low temperatures but is not feasible at high temperatures. A + B C + D temperature. [Total: 15]

A

+ B

C

+ D

Q5(a)

Short Answer 1 mark

Describe and explain the relative basicities of phenylamine, ethylamine and 4-nitrophenylamine. most basic least basic

Q5(b)

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The dye R can be synthesised from 4-nitrophenylamine in two steps. 4-nitrophenylamine step 1 step 2

Q5(i)

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Deduce and draw the structure of the organic salt Q in the box.

Q5(ii)

Short Answer 1 mark

Suggest reagents and conditions for step 1 and 2 in

Q5(ii)(b)

Short Answer 1 mark

. step 1 . step 2 .

Q5(c)

Short Answer 1 mark

Compound G can be synthesised from methylbenzene in three steps. step 1 step 2 step 3

Q5(i)

Short Answer 1 mark

Give the systematic name of compound G.

Q5(ii)

Short Answer 2 marks

Deduce the identities of E and F and draw their structures in the boxes.

Q5(iii)

Short Answer 1 mark

Suggest reagents and conditions for each of steps 1 to 3 in

Q5(iii)(c)

Short Answer 1 mark

. step 1 . step 2 . step 3 . [3] [Total: 13]

Q6(a)

MCQ 4 marks

There are four possible structural isomers of C that contain a benzene ring. Draw the skeletal formulae of the four structural isomers in the appropriate boxes. The number C) NMR spectrum of each compound is given. isomer 1 three peaks in C NMR isomer 2 four peaks in C NMR isomer 3 five peaks in C NMR isomer 4 six peaks in C NMR

C

NMR spectrum of each compound is given.

C

NMR

C

NMR

C

NMR

C

NMR

Q6(b)

Short Answer 1 mark

A three-step synthesis of X (C O) from benzene is suggested as shown. Cl (CH Al Cl step 1 step 2 step 3 X (C

Q6(i)

Short Answer 1 mark

Step 1 is the alkylation of benzene by electrophilic substitution.

Q6(ii)

Short Answer 2 marks

Deduce and draw the structures of W and X in the boxes.

Q6(iii)

Short Answer 1 mark

Suggest the reagents and conditions for step 2.

Q6(iv)

Short Answer 1 mark

Complete the mechanism for the reaction of benzene with the electrophile formed in (b)(i). Include all relevant charges and curly arrows showing the movement of electron pairs. Draw the structure of the intermediate. intermediate [3] [Total: 11] , reacts with hydroxide ions as shown. + 2OH + H and OH . The table shows the results obtained.experiment [OH initial rate 1 0.020 0.030 7.20 × 10 2 0.020 0.120 2.88 × 10 3 0.050 0.030 4.50 × 10

Q6(i)

Short Answer 1 mark

Explain the term order of reaction .

Q6(ii)

Short Answer 1 mark

Use the data in the table to determine the order of reaction with respect to each reactant, and OH Explain your reasoning.

Q6(iii)

Short Answer 1 mark

Use your answer to (a)(ii) to construct the rate equation for this reaction. rate =

Q6(iv)

Short Answer 1 mark

Use your rate equation and the data from experiment 1 to calculate the rate constant, k, for this reaction. Include the units of k. k = units [2] Question 7 continues on the next page.

Q6(b)

Short Answer 1 mark

The decomposition of benzenediazonium ions, C , using a large excess of water, is a The graph shows the results obtained. 0.025 0.020 0.015 0.010 0.005 0 100 200 300 400 time / s 500 600 / mol dm

Q6(i)

Short Answer 1 mark

Draw the structure of the organic product formed in this reaction. [1]

Q6(c)

Short Answer 1 mark

Sketch a concentration-time graph for a zero-order reaction. Use your graph to suggest how successive half-lives for a zero-order reaction vary as the in the table. concentration time successive half-lives decrease no change in successive half-lives successive half-lives increase [1] [Total: 9]

Q8(a)

Short Answer 1 mark

State and explain the relative rate of hydrolysis of acyl chlorides, alkyl chlorides and aryl chlorides. fastest slowest

Q8(b)

Short Answer 3 marks

The drug remifentanil is shown. remifentanil Remifentanil is completely hydrolysed under acidic conditions. Three different organic compounds are formed. Draw the structures for these organic compounds in the boxes.

Q8(c)

Short Answer 1 mark

Compound Y, C , reacts with Na

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Short Answer 1 mark

to evolve bubbles of gas. The proton ( H) NMR spectrum of compound Y in D O is shown. / ppm 21 0

Q8(i)

Short Answer 1 mark

Use this information to suggest a structure for Y.

Q8(ii)

Short Answer 1 mark

Use the Data Booklet, the proton ( H) NMR spectrum and your answer to (c)(i) to complete the table. chemical shift (δ) environment of proton splitting pattern number of H atoms responsible for the peak 0.95 1.90 2.20 [3] [Total: 10] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every UHDVRQDEOHH?RUWKDVEHHQPDGHE\WKHSXEOLVKHU8&/(6WRWUDFHFRS\ULJKWKROGHUVEXWLIDQ\LWHPVUHTXLULQJFOHDUDQFHKDYHXQZLWWLQJO\EHHQLQFOXGHGWKH publisher will be pleased to make amends at the earliest possible opportunity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

Board	CAIE
Level	A Level
Subject	Chemistry
Code	`9701`
Year	2021
Session	May/June
Paper No.	Paper 42
Q&A	84 questions

Chemistry 2021 · May/June · Paper 42

Questions & Model Answers 84 Qs

Paper Details