Edexcel IAL Chemistry Lab Book

8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

PEARSON EDEXCEL INTERNA INTE RNATIONAL TIONAL AS/A LEVEL

CHEMISTRY Lab Book

Published by Pearson Education Limited, 80 Strand, London, WC2R 0RL. www.pearsonglobalschools.com Copies of official specifications for all Pearson Edexcel qualifications may be found on the website: https://qualifications.pearson.com


Text © Pearson Education Limited 2018 Designed by Tech-Set Ltd, Gateshead, UK Edited by Katharine Godfrey Smith, Helen Payne and Stephanie White Typeset by Tech-Set Ltd, Gateshead, UK Original illustrations © Pearson Education Limited 2018 Cover design © Pearson Education Limited 2018 The rights of Carl Howe and Nigel Saunders to be identified as authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. The Publishers would like to thank Mark Woods for his contributions to the text. First published 2018 21 20 19 18 10 9 8 7 6 5 4 3 2 1 British Library Cataloguing in Publication Data A catalogue record record for this book is available available from the British Library Library ISBN 978 1 292 24471 6 Copyright notice All rights reserved. reserved. No part of this publication may be reproduced in any form or by any means (including photocopying or storing it in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright owner, except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency, Barnard’s Barnard’ s Inn, 86 Fetter Lane, London EC4A 1EN (www.cla.co.uk). Applications for the copyright o wner’ wner’s s written permission should b e addressed to the publisher. Printed in Slovakia by Neografia Acknowledgements Acknowledgements All artwork © Pearson Education Education Limited 2018 A note from from the publishers: publishers: While the Publishers have made every attempt to ensure that advice on the qualification and its assessment is accurate, the official specification and associated assessment guidance materials are the only authoritative source of information and should always be referred to for definitive guidance. Pearson examiners have not contributed to any sections in this resource relevant to examination papers for which they have responsibility. responsibility. Examiners will not use this resource as a source of material for any assessment set by Pearson. Neither Pearson, Edexcel nor the authors take responsibility for the safety of any activity . Before doing any practical activity you are legally required to carry out your own risk assessment. In particular, particular, any local rules issued by your employer must be obeyed, regardless of what is recommended in this resource. Where students are required required to write their own risk assessments they must always be checked by the teacher and revised, as necessary, to cover any issues the students may have overlooked. The teacher should always have the final control as to how the practical is conducted.

CONTENTS


INTRODUCTION

2

CORE PRACTICALS OVERVIEW

3

PAPER 3 PRACTICAL SKILLS

4


5

1

MEASUREMENT OF THE MOLAR VOLUME OF A GAS

6

2

DETERMINATION DETERMINA TION OF THE ENTHALPY CHANGE OF A REACTION USING HESS’S LAW

9

3

FINDING THE CONCENTRA CONCENTRATION TION OF A SOLUTION OF HYDROCHLORIC ACID

13

4

PREPARATION PREPARA TION OF A ST STANDARD ANDARD SOLUTION FROM A SOLID ACID AND ITS USE TO FIND THE CONCENTRA CONCENTRATION TION OF A SOLUTION OF SODIUM HYDROXIDE

16

INVESTIGATION INVESTIGAT ION OF THE RA RATES TES OF HYDROL HYDROLYSIS YSIS OF SOME HALOGENOALKANES

19

CHLORINATION OF 2-METHYLPROP CHLORINATION 2-METHYLPROPAN-2-OL AN-2-OL WITH CONCENTRA CONCENTRATED TED HYDROCHLORIC ACID

22

7

OXIDATION OXIDA TION OF PROP PROPAN-1-OL AN-1-OL TO PRODUCE PROP PROPANAL ANAL AND PROPA PROPANOIC NOIC ACID

25

8

ANALYSIS ANAL YSIS OF SOME INORGANIC AND ORGANIC UNKNOWNS 1

31

9A

FOLLOWING THE RA RATE TE OF THE IODINE–PROPAN IODINE–PROPANONE ONE REACTION BY A TITRIMETRIC METHOD

34

INVESTIGATING INVESTIGAT ING A ‘CLOCK REACTION’ (HARCOURT–ESSON, IODINE CLOCK)

37

10

FINDING THE ACTIVA ACTIVATION TION ENERGY OF A REACTION

42

11

FINDING THE K a VALUE FOR A WEAK ACID

46

12

INVESTIGATING INVESTIGAT ING SOME ELECTROCHEMICAL CELLS

49

13A

REDOX TITRA TITRATIONS TIONS WITH IRON(II) IONS AND POT POTASSIUM ASSIUM MANGANA MANGANATE(VII) TE(VII)

52

13B

REDOX TITRA TITRATIONS TIONS WITH SODIUM THIOSULFA THIOSULFATE TE AND IODINE

55

14

PREPARATION OF A TRANSI TRANSITION TION METAL COMPLE COMPLEX X

58

15

ANALYSIS ANAL YSIS OF SOME INORGANIC AND ORGANIC UNKNOWNS 2

61

16

PREPARATION OF ASPIRI ASPIRIN N

67

5 6

9B

ANSWERS

70

MATHS SKILLS

73

1

INTRODUCTION


Practical work is central to the study o chemistry. The International Advanced Subsidiary/Advanced Level (IAS/IAL) specification includes 16 core practical activities that link theoretical knowledge and understanding to practical scenarios. By completing the core practical activities, you will learn to: •

ollow and interpret experimental instructions, covering a range o laboratory exercises throughout the course, with minimal help rom your teacher

•

manipulate apparatus, use chemicals, carry out all common laboratory procedures and use data logging (where appropriate)

•

work sensibly and saely in the laboratory, paying due regard to health and saety requirements

•

gain accurate and consistent results in quantitative exercises, and make the most o the expected observations in qualitative exercises.

By the end o this course, you should be able to use a variety o apparatus and techniques to: •

design and carry out both the core practical practical activities and your own investigations

•

collect data that can be analysed

•

use data to draw valid conclusions.

Your knowledge knowledge and understanding o practical skills and activities will be assessed in all examination papers. •

Papers 1 and 2 (IAS), and 4 and 5 (IAL) will include questions based on practical activities, including novel scenarios.

•

Papers 3 (IAS) and 6 (IAL) will test your ability to plan practical work, including risk management and selection o apparatus.

Assessment or the Practical Skills Papers 3 and 6 will ocus on our main areas: •

independent thinking

•

use and application o scientific methods and practices

•

numeracy and the application o mathematical concepts

•

use o apparatus and equipment.

The ways in which you can demonstrate these practical skills are outlined in the tables on pages 4 and 5. You may wish to tick off each element as you gain confidence. You will find answers and maths skills required or the practicals in the back o the book.

2

CORE PRACTICALS OVERVIEW


UNIT 1 (IAS): FORMULAE, EQUATIONS AND AMOUNT OF SUBSTANCE 1 Measurement o the molar volume o a gas UNIT 2 (IAS): ENERGETICS 2 Determination o the enthalpy change o a reaction using Hess’s Law UNIT 2 (IAS): REDOX CHEMISTRY AND GROUPS 1, 2 AND 7 3 Finding the concentration o a solution o hydrochloric acid 4 Preparation o a standard solution rom a solid acid and its use to find the concentration

o a solution o sodium hydroxide UNIT 2 (IAS): ORGANIC CHEMISTRY: ALCOHOLS, HALOGENOALKANES AND SPECTRA 5 Investigation o the rates o hydrolysis o some halogenoalkanes 6 Chlorination o 2-methylpropan-2-ol with concentrated hydrochloric acid 7 Oxidation o propan-1-ol to produce propanal and propanoic acid 8 Analysis o some inorganic and organic unknowns 1 UNIT 4 (IAL): KINETICS 9a Followin Following g the rate o the iodine–propanone reaction by a titrimetric method 9b Investigating a ‘clock reaction’ (Harcourt–Esson, iodine clock) 10 Finding the activation energy o a reaction UNIT 4 (IAL): ACID–BASE EQUILIBRIA 11 Finding the K a value or a weak acid UNIT 5 (IAL): REDOX EQUILIBRIA 12 Investigating some electrochemic electrochemical al cells 13a Redox titrations with iron(II) ions and potassium manganate(VII) manganate(VII) 13b Redox titrations with sodium thiosulate and iodine UNIT 5 (IAL): TRANSITION METALS AND THEIR CHEMISTRY 14 Preparation o a transition metal complex UNIT 5 (IAL): ORGANIC NITROGEN COMPOUNDS: AMINES, AMIDES, AMINO ACIDS AND PROTEINS 15 Analysis o some inorganic and organic unknowns 2 UNIT 5 (IAL): ORGANIC SYNTHESIS 16 Preparation o aspirin

3



Practical skills Independent thinking in a practical context Solve problems set in a practical context

Core Practical 4 5

1

2

3

6

7

8

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

Apply scientific knowledge to practical contexts

Use and application of scientific methods and practices Identiy and state how to control variables to improve experimental validity Present data in appropriate ways Evaluate results and draw conclusions Appreciate measurement measurement uncertainties and errors Comment on the method or an experiment

Numeracy and the application of mathematical concepts in a practical context Plot and interpret graphs Process and analyse data using appropriate mathematical skills Use appropriate numbers o significant figures based on the experimental data Consider the accuracy and precision o data

Use of apparatus and equipment Recognise a range o laboratory apparatus and select appropriate apparatus or a particular scenario Understand how to use a range o apparatus and techniques appropriate appropriate to the knowledge and understanding included in the specification Consider the range and resolution o apparatus Identiy health and saety issues and discuss how these may be dealt with

4



Practical skills Independent thinking in a practical context Solve problems set in a practical context

9a

9b

10

Core Practical 11 12 13a 13b

9a

9b

10

11

12

13a

13b

14

15

16

9a

9b

10

11

12

13a

13b

14

15

16

9a

9b

10

11

12

13a

13b

14

15

16

14

15

16

Apply scientific knowledge to practical contexts

Use and application of scientific methods and practices Identiy and state how to control variables to improve experimental validity Present data in appropriate ways Evaluate results and draw conclusions Appreciate measurement measurement uncertainties and errors Comment on the method or an experiment

Numeracy and the application of mathematical concepts in a practical context Plot and interpret graphs Process and analyse data using appropriate mathematical skills Use appropriate numbers o significant figures based on the experimental data Consider the accuracy and precision o data

Use of apparatus and equipment Recognise a range o laboratory apparatus and select appropriate apparatus or a particular scenario Understand how to use a range o apparatus and techniques appropriate appropriate to the knowledge and understanding included in the specification Consider the range and resolution o apparatus Identiy health and saety issues and discuss how these may be dealt with

5

CORE PRACTICAL 1:

SPECIFICATION REFERENCE


1.11

Procedure 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

1 Set up the apparatus to capture and measure gas evolved rom a reaction

in the boiling tube. 2 Place 30 cm3 o 1 mol dm−3 ethanoic acid in the boiling tube. 3 Place approximately 0.05 g o calcium carbonate in a test tube. Weigh the

test tube and its contents accurately. 4 Remove the bung rom the boiling tube and tip the calcium carbonate into

the boiling tube. Quickly replace the bung in the boiling tube. 5 Once the reaction is over, measure the volume o gas produced. 6 Reweigh the test tube that contained the calcium carbonate. 7 Repeat the experiment six more times, increasing the mass o calcium

carbonate by about 0.05 g each time. Do not exceed 0.40 g o calcium carbonate.

Learning tips ● Ensure that points points plotted on on a graph take take up more than hal the available available space on each scale. Axes must occupy at least hal o the space on the graph paper. ● Keep scales scales simple: one large square square as 5 or or 10 or 20 is ideal. ideal. A scale where one large square represents 3 or 7 units (or similar) is very difficult to plot on, and this ofen leads to errors. ● Always consider whether whether the graph line should should go through through the origin. ● Straight lines should should be drawn drawn with the aid o a ruler long enough to to cover the ull length o the line.

Results (Use this space to record your results.)

6

Objectives ● To find the the volume volume o o one mole mole o carbon dioxide gas

Equipment ● bo boil ilin ing g tu tube be ● st stan and d and and clam clamp p ● bung fitte fitted d with with delivery delivery tube to fit boiling tube ● wat water er bath bath or or gas col collecti lection on 3 ● 100 cm measuring cylinder ● 50 cm3 measuring cylinder ● tes estt tu tube ● ma mass ss balan balance ce (2 d.p d.p.) .) ● 1 mo mol dm−3 ethanoic acid ● pow powdered dered calc calcium ium carb carbonat onatee !

Safety

● Wear Wear eye prot protectio ection. n. ● Re Remo move ve the the bung bung i the delivery tube gets blocked, clear the blockage and repeat the procedure rom the start. ● Avo Avoid id skin skin conta contact ct with with the the ethanoic acid, especially i the skin is broken or sensitive.

CORE PRACTICAL 1:



1.11

Analysis of results 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

1 Plot a graph o mass o calcium carbonate (on the x-axis) against volume o carbon dioxide collected (on the y -axis). -axis). Draw Draw a straight line o best fit – this line must pass through the

origin.

2 Use your graph to find the volume o carbon dioxide that would be made rom 0.25 g o

calcium carbonate.

3 In this reaction, one mole o calcium carbonate makes one mole o carbon dioxide. Calculate

the number o moles o calcium carbonate in 0.25 g and hence calculate the volume o one mole o carbon dioxide gas in dm 3.

7

CORE PRACTICAL 1:



1.11

Questions 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

1 Write a chemical equation or the reaction between ethanoic acid, CH3COOH, and calcium carbonate.

2 Why is it more accurate to find the mass o the calcium carbonate carbonate used by weighing the test tube containing the

calcium carbonate carbonate and then reweighing the test tube afer the calcium carbonate has been tipped out, rather than by weighing the empty test tube at the start?

3 Identiy the major source o error caused by the procedur proceduree used here.

4 What change to the procedure/apparatus could you make to eradicate this error?

5 Carry out two calculations to show that the ethanoic acid was in excess in all experimental runs.

8

CORE PRACTICAL 2:




6.7

Objectives

1 Place approximately 3 g o solid potassium carbonate in a test tube.

Accurately Accurat ely weigh the test tube and its contents. 2 Use a burette to dispense 30 cm cm3 o 2 mol dm–3 hydrochloric acid into a

polystyrene cup, which is supported in a beaker. 3 Measure the temperature o the acid.

carbonate to the acid, stirring all the time and 4 Gradually add potassium carbonate monitoring the temperature o the acid.

● To calcul calculate ate the molar molar enthalpy change or two reactions and use Hess’s Law to determine the enthalpy change or the reactions

Equipment ● tw two o test test tub tubes es

5 Reweigh the empty test tube. 6 Repeat steps 1–5 using approximately 3.5 g o potassium hydrogencarbonate

instead o the potassium carbonate. This time, record the lowest temperature reached.


● 2 mol dm–3 dilute hydrochloric acid ● soli solid d potas potassium sium carb carbonat onatee ● solid solid pot potas assiu sium m hydrogencarbonate ● thermomet thermometer er able able to to read read up up to 50 °C or more

Mass o test tube with potassium carbonate/g Mass o test tube afer emptying out potassium carbonate/g

● pol polys ysty tyren renee cup cup ● 250 cm3 or 400 cm cm3 beaker

Mass o potassium carbonate used/g

● bur burett ette, e, clamp clamp and stan stand d

Start temperatur temperature/°C e/°C

● st stir irri ring ng ro rod d ● ma mass ss balan balance ce (2 d.p d.p.) .)

Highest temperatur temperature/°C e/°C

● sp spaatu tulla

Temperature change/°C

!

Safety

● We Wear ar eye prot protectio ection. n. Mass o test tube with potassium hydrogencarbonate/g Mass o test tube afer emptying out potassium hydrogencarbonate/g

Mass o potassium hydrogencarbonate used/g Start temperatur temperature/°C e/°C Lowest temperature/°C Temperature change/°C

9

● Avoid Avoid skin skin conta contact ct with with the the reactants and products.

CORE PRACTICAL 2:



Learning tips 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

● You can can assume that the heat heat capacity o the final solution is the same same as the heat capacity capacity o water. The volume o water produced in the reaction is so small it can be ignored. ● For exotherm exothermic ic reactions reactions,, the enthalpy enthalpy change, change, △H, is negative. ● Be careul to to use equals signs correctly correctly.. It is very easy to to end up stating that a negative negative number equals a positive number.

Analysis of results 1 The equations or the reactions occurring are:

reaction 1: K2CO3(s) + 2HCl(aq) → 2KCl(aq) + CO 2(g) + H2O(l) reaction 2: KHCO3(s) + HCl(aq) → KCl(aq) + CO 2(g) + H2O(l) Calculate the energy change or each reaction in J. (The specific heat capacity o water is Calculate 4.2 J g–1 °C–1.)

Calculatee the enthalpy change, △H, or each reaction in kJ mol–1. 2 Calculat Assume that the hydrochloric acid is in excess.

3 Use your results to calculate the enthalpy change or the thermal decomposition o

potassium hydrogencarbonate: reaction 3: 2KHCO3(s) → K2CO3(s) + CO2(g) + H2O(l)

10

6.7

CORE PRACTICAL 2:




1 Why is it not possible to measure the enthalpy change or the decomposition o potassium

hydrogencarbonate directly?

hydrochloric ric acid is in excess in both reactions. 2 Show that the hydrochlo

11

6.7

CORE PRACTICAL 2:



3 Draw an energy level diagram or each reaction: 1, 2 and 3. 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

4 Explain why the reactions are conducted in a polystyrene cup rather than a glass beaker.

12

6.7

CORE PRACTICAL 3:


FINDING THE CONCENTRATION CONCENTRATION OF A SOLUTION OF HYDROCHLORIC ACID


8.21

Objectives

1 Wash out the 250

cm 3 volumetric

flask with distilled water.

2 Use the pipette to transer 25.0 cm3 o the hydrochlo hydrochloric ric acid solution into

the volumetric flask. Use distilled water to make the solution up to the mark. 3 Prepare your apparatus or the titration. The burette should contain the

sodium hydroxide solution (previously standardised) and the conical flask should contain the dilute hydrochloric acid solution. hydrochloric acid into the conical 4 Pour a 25.0 cm3 aliquot o the diluted hydrochloric flask. Use phenolphthalein as the indicator. 5 Titrate the contents o the flask against the sodium hydroxide solution.

Record all burette readings to the nearest 0.05 cm 3.

● To find the the concen concentrat tration ion o a solution o hydrochloric acid

Equipment ● bure burette, tte, clam clamp p and and stand stand ● sodium sodium hydr hydroxid oxidee solutio solution n 3 (approximately 0.08 dm , previously standardised) ● bench bench hydr hydrochl ochloric oric acid (approximately 1 mol dm–3) ● phe phenol nolpht phthal halein ein

6 The end point o this titration is indicated by the contents o the flask

becoming pale pink. Continued swirling will cause the pink colour to ade and disappear. I the pink colour persists or 5 seconds or more, the end point has been reached.

● 250 cm3 conical flask ● 25 cm3 volumetric pipette plus saety filler

7 Conduct urther titrations until you have two concordant concordant titres.

● 100 cm3 beakers or transer o solutions

8 Ask your teacher or a technician to check one o your burette readings.

● un unnel nel or or filling filling buret burette te

9 Record your results in the table below.

● 250 cm3 beaker ● 250 cm3 volumetric flask

Learning tips

!

● Do not include include your your rough titration when calculating your mean. mean.

● Wear Wear eye eye protect protection. ion. Gogg Goggles les are preerred as sodium hydroxide is particularly hazardous to the eyes.

● Give all all burette burette readings readings to the nearest nearest 0.05 0.05 cm3. ● When you scale up to find the number number o moles in the ull volume volume o solution in the volumetric flask, use this equation:

● Avoid Avoid skin skin conta contact ct with with the the acid, alkali and indicator.

number o moles in ull volume

ull volume × number o moles in aliquot volume = ______________________________________________ aliquot volume in which you know the number o moles

● Always Always use a pipet pipette te filler; filler; never use your mouth to suck the liquid up. ● Take care care when when clampin clamping g and filling the burette that it does not crack or topple over.

Results (Use this space to record your results.) Rough

Safety

Trial 1

Final burette reading/cm3 Initial burette reading/cm3 Titre/cm 3 Concordant Concor dant (Y/N)

13

Trial 2

Trial 3

Trial 4

CORE PRACTICAL 3:




1 Calculate the mean titre using your two concordant results.

Calculatee the number o moles o sodium hydroxide that were contained in your mean titre. 2 Calculat

Calculatee the number o moles o hydrochl hydrochloric oric acid that were contained in the ull 250 cm cm 3 o 3 Calculat diluted hydrochloric acid.

Calculatee the concentra concentration tion o the original solution o hydrochloric acid. 4 Calculat

14

8.21

CORE PRACTICAL 3:



8.21


1 Write a chemical equation or the reaction o hydrochloric acid with sodium hydroxide.

2 The pink colour seen at the end point ades because the excess sodium hydroxide hydroxide reacts with carbon dioxide in

the air. This reaction produces sodium carbonate. a Write an equation or the reaction o sodium hydroxide with carbon dioxide.

b When sodium hydroxide solution is stored, it reacts with carbon dioxide in the air. i

How will this change the concentra concentration tion o the sodium hydroxide solution?

ii How will this affect the volume o sodium hydroxide solution required to reach the end point in the

titration? Explain your answer.

3 Explain why it is better to have a titre o around 25 cm 3 than a titre o around 10 cm3.

15

CORE PRACTICAL 4:


PREPARATION PREPARA TION OF A ST STANDARD ANDARD SOLUTION FROM A SOLID ACID AND ITS I TS USE TO FIND

8.23

THE CONCENTRATION OF A SOLUTION OF SODIUM HYDROXIDE


1 Weigh an empty test tube. Scoop approximately 2.5 g o sulamic acid into

the test tube. 2 Accurately reweigh the test tube and its contents. 3 Dissolve the sulamic acid in approximately 100 cm cm3 o water in a beaker. 4 Transer the solution, including the washings, to a 250 cm 3 volumetric

flask and use distilled water to make up the solution to the mark. 5 Prepare your apparatus or the titration. The burette will contain the acid

and the conical flask will contain the sodium hydroxide solution.

Objectives ● To make make a solutio solution n o a known known concentration o acid and use it to find the concentra concentration tion o a solution o sodium hydroxide

Equipment ● bure burette, tte, clam clamp p and and stand stand ● sol solid id sul sulami amicc acid acid ● sodium sodium hydro hydroxide xide solu solution tion o unknown concentration

6 Pour a 25.0 cm3 aliquot o sodium hydroxide solution o unknown

concentration concentra tion into the 250 cm3 conical flask. 7 Use methyl orange as the indicator.

● methy methyll oran orange ge indic indicator ator

8 Titrate the contents o the flask against the sulamic acid solution you

● 250 cm3 conical flask ● 25 cm3 volumetric pipette plus saety filler

prepared. Burette readings should be to the nearest 0.05 cm3. 9 Conduct urther titrations until you have two concordant titres. 10 Record your results in the table below.

● 100 cm3 beaker or transer o solutions

Learning tips

● un unnel nel or or filling filling buret burette te

● Indicators are very dilute dilute weak acids. acids. The The more indicator indicator you add, add, the less accurate your titration result will be.

● 250 cm3 beaker

● When conducting conducting a titration, titration, use distilled distilled water to to wash down down the inside o o the conical flask rom time to time.

● ma mass ss balan balance ce (2 d.p d.p.) .)

● When you scale up to find the number number o moles in the ull volume volume o solution in the volumetric flask, use this equation:

● 250 cm3 volumetric flask

!

● Wear Wear eye eye protect protection. ion. Gogg Goggles les are preerred as sodium hydroxide is particularly hazardous to the eyes.

number o moles in ull volume

ull volume × number o moles in aliquot volume = ______________________________________________ aliquot volume in which you know the number o moles

● Avoid Avoid skin skin con contact tact with sulamic acid and sodium hydroxide. ● Take care care when when clampin clamping g and filling the burette that it does not crack or topple over.


Mass of sulfamic acid = Rough

Safety

Trial 1

Final burette reading/cm3 Initial burette reading/cm3 Titre/cm 3 Concordant Concor dant (Y/N)

16

Trial 2

g Trial 3

Trial 4

CORE PRACTICAL 4:

SPECIFICATION

PREPARATION PREPARA TION OF A ST STANDARD ANDARD SOLUTION FROM A SOLID ACID AND ITS I TS USE TO FIND THE CONCENTRATION OF A SOLUTION OF SODIUM HYDROXIDE


1 Calculate the concentration o your sulamic acid solution. The Mr o sulamic acid is 97.1.

2 Calculate the mean titre using your concordant results.

3 Calculat Calculatee the number o moles o sulamic acid in your mean titre.

4 Sulamic acid is a monoprotic acid. This means that one mole o sulamic acid will react exactly with

one mole o sodium hydroxide. Calculate the concentration o the sodium hydroxide solution used.

17

REFERENCE

8.23

CORE PRACTICAL 4:

SPECIFICATION

PREPARATION PREPARA TION OF A ST STANDARD ANDARD SOLUTION FROM A SOLID ACID AND ITS I TS USE TO FIND THE CONCENTRATION OF A SOLUTION OF SODIUM HYDROXIDE


1 A 250 cm3 volumetric flask has an accuracy o ±0.6 cm 3. Calculate the percentage uncertainty

in the volume o the sulamic acid solution in the volumetric flask.

2 Each burette reading is accurate to ±0.05 cm 3. Calculate the percentage uncertainty in one o

your titres.

3 Why should the pipette be rinsed with the sodium hydroxide hydroxide solution afer it has been

washed with water?

4 Why is there no need to dry the conical flask afer washing it out between trials?

5 Identiy another indicator you could use in this titration, and state the colour change you

would see at the end point.

18

REFERENCE

8.23

CORE PRACTICAL 5:


INVESTIGATION OF THE RATES OF HYDROLYSIS OF SOME HALOGENOALKANES


10.11

Objectives

Part 1 1 Set up a water bath by filling the 250 cm3 beaker up to the three-quarters

mark with water at around 50 °C. 2 Take three test tubes and add 5 cm 3 o ethanol to each one. 3 Add our drops o 1-iodobutane to the first tube, our drops o

1-bromobutane to the second tube and our drops o 1-chlorobutane to the third tube. Label the tubes. 4 Loosely place a bung in each test tube and place the test tubes in the

water bath. 5 Take three clean test tubes and pour 5 cm 3 o silver nitrate solution into

each one. Then place the test tubes in the water bath. 6 When the halogenoal halogenoalkane–ethanol kane–ethanol solutions have reached the

temperature o the water bath, add one test tube o silver nitrate solution to one o the halogenoalkane–ethanol solutions and replace the bung. At the same time, start the stop clock. 7 Measure the time taken or a precipitate to appear. As soon as the solution

becomes cloudy, stop the stop clock.

● To investig investigate ate the the relativ relativee rates o hydrolysis o primary, secondary and tertiary halogenoal halogenoalkanes kanes and o chloro-, bromo- and iodoalkanes

Equipment ● 250 cm3 beaker ● 12 test test tubes tubes with with bung bungss ● 11-ch chlo loro robu buta tane ne ● 11-br brom omob obut utan anee ● 11-io iodo dobu buta tane ne ● 22-br brom omob obut utan anee ● 2-bro 2-bromo-2mo-2-methy methylpro lpropane pane ● 0.05 0.05 mo moll dm dm–3 silver nitrate solution

halogenoalkanes. 8 Repeat steps 6 and 7 or the other two halogenoalkanes.

● 15 cm3 ethanol

Part 2

● dro droppi pping ng pip pipett ettes es

2-bromobutane and 9 Repeat Part 1 using 1-bromobutane, 2-bromobutane

● two 10 10 cm3 measuring cylinders

2-bromo-2-methylpropane 2-bromo-2-methylp ropane instead o the other halogenoa halogenoalkanes. lkanes.

● st stop op cl cloc ockk ● lab labels els or or test test tub tubes es


● kettle !

Safety

● Wear eye eye prot protect ection ion.. ● Avoid Avoid skin skin conta contact ct with with the the reactants. ● There There mus mustt be no no naked naked flames in the vicinity as ethanol and halogenoalk halogenoalkanes anes are highly flammable. ● The labo laborato ratory ry needs needs to to be well ventilated to prevent the inhalation o umes.

19

CORE PRACTICAL 5:



Learning tips 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

● The hydrolysis hydrolysis o halogenoalk halogenoalkanes anes is a nucleophilic nucleophilic substitution substitution reaction. reaction. ● In this investigation, the nucleophile nucleophile is water water.. ● NaOH can be used instead instead o water water to hydrolyse hydrolyse the halogenoalkanes halogenoalkanes but then any any excess NaOH NaOH must be neutralised by HNO3 beore the AgNO3 is added. Otherwise a precipitate o Ag 2O will orm.

Analysis of results 1 Describe the pattern shown in your results or Part 1.

2 Describe the pattern shown in your results or Part 2.

Questions 1 Write an equation or the reaction o 1-bromobutane with water.

2 In these reactions, a precipitate orms. Identiy the precipitate ormed when the halogenoalkane

is 1-iodobutane.

20

10.11

CORE PRACTICAL 5:



3 Explain why ethanol is used in these reactions. 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

4 Explain why water is able to act as a nucleophile.

5 Explain why water is used as the nucleophile rather than hydroxid hydroxidee ions.

6 Draw skeletal ormulae or each o the halogenoa halogenoalkanes lkanes used in this investigation (there are five o them).

Classiy each halogenoalkane as primary, secondary or tertiary.

21

10.11

CORE PRACTICAL 6:


CHLORINATION CHLORINA TION OF 2-METHYLPROP 2-METHYLPROPAN-2-OL AN-2-OL WITH CONCENTRA CONCENTRATED TED HYDROCHLORIC ACID


Pour 10 cm3 o

Objectives 2-methylpropan-2-ol and 35 cm3 o

concentrated concentrated hydrochloric acid into a large conical flask. Very gently swirl the contents o the flask. Place the bung in the mouth o the flask. Gently swirl again, then remove the bung to release the pressure. Continue swirling the mixture with the bung fitted, and then releasing the pressure, or around 20 minutes. You should see two layers in the flask. The upper layer is the crude product. Add approximately 6 g o powdered anhydrous calcium chloride to the flask and swirl until it has dissolved. This will ensure that any unreacted alcohol is in the lower aqueous layer. Transer the reaction mixture to a separating unnel. Allow the mixture to settle into the two layers. Run off and discard the lower layer. Retain the upper organic layer in the separating unnel. Add approximately 20 cm3 o sodium hydrogencarbonate solution to the separating unnel. Swirl the unnel. The production o carbon dioxide will cause the pressure to increase; remove the bung at requent intervals to release this pressure. Run off and discard the lower aqueous layer. Repeat the washing with sodium hydrogencarbonate solution, shake the separating unnel, and release the carbon dioxide gas produced, at requent intervals. Run off and discard the lower layer. Ensure none o the aqueous layer remains in the tap. Run off the organic layer into a small conical flask. Add a ull spatula o anhydrous sodium sulate. Place the bung in the flask and swirl the contents to mix. Leave the mixture until the liquid looks completely clear, swirling occasionally. Decant the organic liquid into a 50 cm3 pear-shaped (or round-bottomed) flask. Set up the flask or distillation. Collect the raction boiling between 50 °C and 52 °C. Place your pure product in a labelled sample tube. Carry out the test described in the ‘Analysis’ section o this practical.

1

2 3

4

5

6

7

8 9

10 11 12 13 14

Learning tips

● To produce produce and and puriy puriy a sample sample o 2-chloro-2-methylpropa 2-chloro-2-methylpropane ne

Equipment ● 250 cm3 conical flask with bung ● 100 cm3 (or larger) separating unnel with bung ● 250 cm3 beaker or liquid run off rom separating unnel ● filter filter unnel unnel to to fit separ separating ating unnel ● apparatu apparatuss or or distil distillatio lation n 3 with 50 cm pear-shaped (or round-bottomed) round-bottom ed) flask and thermometer able to read up to 100 °C ● 25 cm3 and 100 cm cm3 measuring cylinders ● 2-m 2-meth ethyl ylpro propan pan-2-2-ol ol ● 0.1 0.1 mo mol dm dm–3 sodium hydrogencarbonate solution ● 6 g powde powdered red anhy anhydro drous us calcium chloride ● anhy anhydrou drouss sodium sodium sul sulate ate ● smal smalll conical conical flas flasks ks with with bungs bungs ● sa samp mple le tu tube be ● 0.05 0.05 mo moll dm dm–3 silver nitrate solution ● dilut dilutee (0.5 mol dm–3) sodium hydroxide solution ● dil dilut utee (0.1 mol dm–3) nitric acid ● 70 cm3 concentrated hydrochloric acid

● The OH group in an alcohol alcohol can can be replaced replaced by a halogen. halogen. As well as the method used here to chlorinate an alcohol, PCl 5 can be used to make a chloroalkane. HBr (which is made in situ) can be used to make a bromoalkane. Red phosphorus with iodine can be used to make an iodoalkane.

● te test st tu tube bess

● You can can check the purity purity o a substance substance by measuring measuring its boiling boiling temperature. temperature.

● bea beake kerr or wa wate terr bath bath

!

● ● ● ● ● ●

10.14

● sp spaatu tullas ● 5 cm3 ethanol ● Bu Buns nsen en bu burn rner er

Safety

This procedure procedure requires requires the use o o a working ume cupboard. cupboard. Wear eye protection. protection. Goggles are are preerred. preerred. Avoid skin contact with the reactants and products. products. Wear Wear gloves. Avoid Avoi d inhalin inhaling g vapour vapours. s. The product product o the distillation distillation process process is flammable. The umes rom the concentrated concentrated hydrochloric hydrochloric acid are toxic and corrosive corrosive and must not be inhaled, especially especially by anyone with a respiratory problem. 22

CORE PRACTICAL 6:



Results (Use this space to record your results.) 8 1 0 2 n o s r a e P © . t r a p n i r o e l o h w n i n o i t u b i r t s i d r o n o i t a l u c r i c , e l a s e r r o f t o N . n o i t e r c s i d r e h s i l b u p t a e g n a h c o t t c e j b u s t n e t n o c l l a , f o o r p d e t c e r r o c n U

Analysis of results Perorm the ollowing test on the distillate. 1 Place a ew drops o the distillate in a test tube. 1 Add 5 cm3 o ethanol and 1 cm3 o aqueous sodium hydroxide to the test tube. 3 Warm the mixture in a water bath. 4 Add excess nitric acid to the mixture ollowed by a ew drops o silver nitrate solution.

Describe what you see.

23

10.14

CORE PRACTICAL 6:




1 Write an equation or the reaction o 2-methylpropan-2-ol with concentrated hydrochloric acid.

2 What is removed rom the crude product when it is shaken with sodium hydrogencarbonate hydrogencarbonate solution?

Write an equation or any reaction that occurs.

3 2-methylpropan-2-ol has a boiling temperature o 82 °C and is soluble in water.

2-chloro-2-methylpropane has a boiling temperature o 51 °C and is insoluble in water. Explain these differences.

24

10.14

Edexcel IAL Chemistry Lab Book

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