Chemistry 2021 May/June | Past Paper

Q1

Short Answer 1 mark

A Group 2 metal combines with bromine to form a crystalline solid, MBr Excess aqueous AgNO is added to a solution of MBr and a precipitate forms. The mixture is filtered. The precipitate is dried and the mass of the precipitate is recorded.

Q1(a)

Short Answer 1 mark

State the formula and colour of the precipitate.

Q1(b)

Short Answer 3 marks

Complete the equation to represent the reaction between MBr and AgNO + AgNO contains 8.415 × 10 Calculate the relative formula mass, M , of MBr . Use this to identify M. Show your working. = M =

Q1(d)

Short Answer 1 mark

A sample of MBr is dissolved in water. Chlorine gas is then bubbled into the solution.

Q1(i)

Short Answer 1 mark

Describe the observations for this reaction.

Q1(ii)

Short Answer 1 mark

Name the type of reaction that occurs when MBr reacts with chlorine gas.

Q1(e)

Short Answer 1 mark

Compound Y is a pure insoluble solid which contains halide ions. A single reagent is added directly to compound Y to determine the halide ion present. Identify the reagent added. State the observation which would confirm that Y contains bromide ions. reagent observation [2] anion present in each sample.

Q1(i)

Short Answer 1 mark

Explain how the action of heat is used to identify which sample is:

Q1(ii)

Short Answer 1 mark

Complete the electron configuration of the magnesium cation present in these salts.

Q1(g)

Short Answer 1 mark

A sample of MgCO

Q1(s)

Short Answer 1 mark

is distinguished from a sample of Mg(OH)

Q1(s)

Short Answer 1 mark

by adding a small amount State one similarity and one difference in these two reactions. similarity difference [2] [Total: 16]

Q2

Short Answer 1 mark

The strength of interaction between particles determines whether the substance is a solid, liquid or gas at room temperature.

Q2(a)

Short Answer 1 mark

Lithium sulfide, Li when it is molten.

Q2(i)

Short Answer 1 mark

Give the formulae of the particles present in solid lithium sulfide.

Q2(ii)

Short Answer 1 mark

Explain, in terms of the structure of the crystalline solid, why lithium sulfide has a high melting point.

Q2(b)

Short Answer 1 mark

Carbon monoxide, CO, is a gas at room temperature and pressure. It contains a coordinate bond.

Q2(i)

Short Answer 1 mark

Explain what is meant by coordinate bond.

Q2(ii)

Short Answer 2 marks

Draw a 'dot-and-cross' diagram to show the arrangement of outer electrons in CO. Show the electrons belonging to the C atom as

Q2(c)

Short Answer 1 mark

Nitrogen, N , is also a gas at room temperature and pressure. Neither CO nor N is an ideal gas.

Q2(i)

Short Answer 2 marks

State two assumptions that are made about the behaviour of particles in an ideal gas. 1 2

Q2(ii)

Short Answer 1 mark

Explain why N does not behave as an ideal gas at very high pressures.

Q2(iii)

Short Answer 1 mark

Complete the table by naming all the types of intermolecular forces (van der Waals') in separate samples of N

Q2(g)

Short Answer 1 mark

and CO(g).

Q2(g)

Short Answer 1 mark

CO

Q2(g)(g)

Short Answer 1 mark

number of electrons per molecule 14 14 intermolecular forces (van der Waals')

Q2(iv)

Short Answer 1 mark

Suggest why the bond in a molecule of CO contains a dipole moment. [Total: 13] a few drops of phenolphthalein indicator. A stopwatch is started as soon as the substances are mixed. The time taken for the pink colour to disappear is recorded. The experiment is repeated at different temperatures, keeping all concentrations and volumes of reagents constant. temperature time taken for 20 300 25 65 35 20

Q2(a)

Short Answer 1 mark

Explain what is meant by the term rate of reaction. represents the activation energy for the reaction. proportion of molecules with a given energy molecular energy have sufficient energy to react.

Q2(ii)

Short Answer 1 mark

Use the same axes to sketch the distribution of energies of molecules in a sample of

Q2(iii)

Short Answer 1 mark

State the effect of an increase in temperature on E for this reaction.

Q2(aq)

Short Answer 3 marks

Show the intermediate formed in this reaction. Include all charges, partial charges, lone pairs and curly arrows as appropriate.

Q2(ii)

Short Answer 1 mark

Name the mechanism for this reaction. on the time taken for the pink colour to disappear. Explain your answer. [Total: 11]

Q4(a)

Short Answer 1 mark

The table shows the structural formulae of four compounds, A, B, C and D, with molecular formula C

Q4(i)

MCQ 4 marks

Complete the table by giving the systematic name of A, B, C and D. structural formula name A CH CH=CH CC CC D CH =C(CH

A

CH

D

CH

Q4(ii)

Short Answer 1 mark

Explain what is meant by stereoisomerism.

Q4(b)

Short Answer 1 mark

W is an alkene with formula C . It reacts with HBr to form two possible carbocations,

Q4(h)

Short Answer 1 mark

(CH ) and H

Q4(i)

Short Answer 1 mark

Identify W as compound A, B, C or D.

Q4(ii)

Short Answer 1 mark

Draw the skeletal formula of the major organic product formed when HBr reacts with W. Explain why this is the major organic product. [3] Identify the role of concentrated sulfuric acid in this reaction.

Q4(d)

Short Answer 1 mark

Alcohol Y reacts completely when warmed with acidified Cr to form Z. Z is distilled from the reaction mixture as soon as it is made. Tollens' reagent is added to a sample of Z and warmed. A silver mirror forms.

Q4(i)

Short Answer 1 mark

Name the type of reaction that occurs when Y reacts to form Z. functional group present in Z aldehyde ketone carboxylic acid [1] [Total: 12]

Q5

Short Answer 1 mark

S is a secondary alcohol with molecular formula C

Q5(a)

Short Answer 1 mark

Draw the displayed formula of S. [1] step 1PBr step 2 U step 3 dilute acid In step 1, the secondary alcohol S reacts with PBr to produce T, which has molecular formulaBr.

Q5(i)

Short Answer 1 mark

Give the systematic name of T.

Q5(ii)

Short Answer 1 mark

Name the type of reaction that occurs in step 1.

Q5(iii)

Short Answer 1 mark

State the reagent

Q5(iii)(s)

Short Answer 1 mark

and conditions for step 2.

Q5(iv)

Short Answer 1 mark

Step 3 involves heating C CN with dilute acid to form V. Complete the equation for this reaction. CN + H + H

Q5(v)

Short Answer 1 mark

An unlabelled sample contains either S, T or U. The sample produces the infrared spectrum shown. transmittance/ % 4000 3000 2000 wavenumber / cm 1500 1000 500 Explain how this spectrum confirms that the unknown sample contains U. In your answer identify one relevant absorption in the infrared spectrum and the bond that [Total: 8] 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
Q&A	49 questions

Chemistry 2021 · May/June

Questions & Model Answers 49 Qs

Paper Details