1ml 2ml 3ml 4ml

Poly Vinyl Alcohol and Borax a High

Viscosity Solution A.K.A

Natural Slimes

Chemistry Of Slime

‘Killing’ SlimeThe more Borax we add, the more cross links are formed between

the polymer chains, this makes the slime more viscous. Because of

this, slime containing more Borax (4ml) barely moves in 10

minutes, whereas the slime containing the least Borax (1ml)

reaches the bottom of the container.

Slime Viscosity

The bonds formed when slime

is made are weak so when

acid is added they are easily

broken. The Borate associates

with acid instead of the

hydroxyl groups. The cross

links are destroyed and the

slime ‘killed’- becomes liquid.

Adding base to this liquid

neutralises the acid and

allows the Borate to re-

associate with the polymer

chains. The slime is revived!

This process can be repeated

several times.

Fish are very slimy

creatures, they use

their slime to regulate

body temperature and

to act as a barrier

against parasites and

germs.

Slime occurs in nature and is also used synthetically. Snails and slugs are the

most commonly encountered slimy land based animal using slime to help them move.

Slime has properties of both solids and liquids. It can be torn like a

solid but can also mould to the shape of it’s container.

Borate ions fit perfectly with the

hydroxyl groups on the polymer chains.

This process traps water within the 3D

lattice structure. The water constantly

evaporates keeping the slime cool.

Universal indicator was

added to the slime to

monitor changes in the pH.

Poster produced by Year 10 Work Experience students between July 6th – 10th 2009

Distance travelled by slime after 10 minutes

CH3CH 3

OH OH O H O H OH O H O H O H OH

CH 3 C H3

OH O H O H O H O H O H OH O H O H

B-

OHOH

OH OH

B-

OHOH

OH O H

Weak Hydrogen

Bonds

It can be made using

Poly Vinyl alcohol (PVA) and

Borax. Borax slowly creates

cross links between two PVA

polymer chains using weak

hydrogen bonds. This creates

a semi-rigid 3D lattice

structure.

Piotr Gorski Highdown SchoolOlivia Sweeney Waingels school

Chemistry Department

Outreach Team.

My work experience week at Reading University chemistry department.

During the work experience week in the chemistry department, I was responsible for the preparation of an iodine clock reaction. This was

going to be tested by a group of local A' level chemistry teachers as part of the departments chemistry demonstration evening on the

Wednesday evening - so no pressure there then !

I made four different solutions, each to a specific

concentration, by using my new found knowledge of what a

mole is. If I didn’t get the measurements correct, then the

experiment wouldn’t work. I used these solutions to prepare

five of the iodine clock reactions. These varied in size from

100 mL to 2 L The reaction systems had to be tested to

ensure that the time for the blue iodine colour to appear was

constant.

During the testing of this experiment, we found that the

mixture of chemicals could not be prepared and left to stand,

as this effected the time it took for the solution to turn

blue/black.

Luckily, when the teachers performed their test, each solution

turned blue/black within seconds of each other.

This demonstration shows that it is the concentration, and not the quantity of a substance which is important in determining how long a reaction will take.

Mixing chemicals was not all I did during this week, I also got the chance to visit the analytical equipment here at the University. I found this really interesting and it amazed me that technology is so advanced and you can view things in such great detail. I had a great week at the University. I learnt lots

of new things and it was a really good work experience.

Some of the other interesting demonstrations prepared for the teachers.

Balloon torture-

holding a balloon

over a candle

flame and it

doesn’t pop!

The visualisation

of convection

currents in a

large 10L beaker

Plus some spectacular

reactions:

aluminium and iodine

potassium permanganate

and glycerol (note the lilac

flame colour).

Preparing and testing the clock reaction Success - it works for the teachers

Harriet Wilkinson Highdown School and Sixth Form Centre, Reading 2008Chemistry Department

Outreach Team.

O O

O H

C H 3

O

2-(acetyloxy)benzoic acid

C H 3

O O

O C H 3

acetic anhydride

O H O

O H

salicylic acid

O H

O

C H 3 + +

acetic acid

2-hydroxybenzoic acid ethanoic anhydride ethanoic acid

aspirin

[ H + ] cat

Reflux

Aspirin is one of the most commonly used drugs in the world, so why not bring chemistry out of the text books, and synthesise aspirin in the

undergraduate chemistry laboratory at Reading University. Using familiar A' level chemistry, you will produce aspirin using an esterification reaction

with ethanoic anhydride. The starting material, for this synthesis, is 2-Hydroxybenzoic acid (salicylic acid)., Salicylic acid is the naturally occurring

analgesic, that can be extracted from willow bark, but is very bitter and less effective than aspirin.

What the students thought about the aspirin synthesis:

“Very interesting and fun to do”“We used different types of equipment not available at school”

“It showed the usefulness of chemistry in real-life situations”

Aspirin synthesis for AS/A2 Level chemistry.

The aspirin is formed when you reflux

ethanoic anhydride, phosphoric acid,

and 2-hydroxybenzoic acid together for

15 minutes. Quenching the reaction

mixture with cold water forces the crude

aspirin out of solution. This crude aspirin

can then be isolated by filtration.

The reaction

The crude aspirin obtained, is

purified by re-crystallisation from

a minimum volume of hot

aqueous ethanol. The pure aspirin

crystals formed are separated and

dried by vacuum filtration

Re-crystallisation

The purity of your aspirin sample

can then be assessed by using

both: thin layer chromatography

(TLC), with visualisation by U.V.

and determination of its melting

point.

Testing the product The pure aspirin

aspirin2-(acetyloxy)benzoic acid

At the end, the

teacher may be

on their knees,

but they’re

still smiling.

Charlie Archer, The Oratory School, Reading, 2008

Chemistry Department

Outreach Team.

Extraction of the Essential Oil Limonene from Oranges.

Orange peel cut into small pieces,

placed into 100 mL of water

Steam Distillation of Orange Peel

Initially an oily water / limonene mixture can be

seen condensing on the glassware at a

distillation temperature of 98 C. The

temperature will rise to 100oC as the distillate

composition approaches pure water.

Limonene can be

observed as an

oily suspension in

the final distillate

(80 mL).

Extraction of Limonene from the

Distillate

limonene (150mg)

obtained from 15 g

of orange peel skin.

The limonene has

an intense aroma of

oranges

To finalise the

extraction, the ether

layer (b.pt. 37oC)

was evaporated on

a water bath to

leave the limonene

(b.pt. 176oC).

Evaporation of the Solvent

The lower layer is the

remaining aqueous distillate

Limonene, an alkene, is

extracted into a low density

water immiscible solvent (ether).

Low molecular weight water

immiscible compounds can

be separated from natural

products by steam

distillation. In this case steam

distillation is used to isolate

the essential oil limonene

from the orange peel.

Limonene is concentrated in the peel of an

orange. The orange peel has two distinct layers,

the skin and the pith. Limonene Is not distributed

evenly between these two layers. Experimentation

has shown that only minimal quantities of

limonene can be extracted from the white pith.

Skin

Mass of Orange Peel

Pith

This outer skin

accounts for two –

thirds of the mass

of the peel. The

best yields of

limonene are

obtained by using

only this outer skin.

Lavender Patchouli Bergamot Cinnamon

Essential oils can be steam distilled from flowers, leaves, fruits, barks and woods

Essential oils are

found in many

household products,

ranging from high end

cosmetics to basic

cleaning materials.

Ahmed Saleh, Denefield school, Reading 2008

The Distillation

Heat

The yield of limonene is about 1% using this

outer skin. This is a large yield compared to

other essential oil extractions, where yields

can range from 1-0.01 % by mass.

Limonene’s structure

Chemistry Department

Outreach Team.

Looking into invisible Invisible inks have been used as a means of communicating secret messages for hundreds of years. These inks have been valuable for a wide range of uses, includingespionage, anti- counterfeiting, property marking, children’s games, within manufacturing and many more. There are many different methods available, and selecting theright one is vital to the success of any secret communication.

The heat revealThe Chemical reveal

UV Visibility Some methods use reactions between the ink and another chemical to develop the message. 1. Due to the pH of some inks, indicators can be used to produce a colour change 2. The ink may simply react with another chemical to give a coloured compound. Using an indicator, particularly Phenolphthalein, with Ammonia gives excellent invisibility and is non-permanent when revealed, making it an ideal method.

Throughout history secret messages often needed to be revealed rapidly and without arousing suspicion. For this reason Invisible inks would often need to be written and revealed with easily obtainable materials. A variety of household products were tested for their suitability as invisible inks and charring was used to reveal the messages.

Adam Young and Toby Parrott. Year 10 The Emmbrook 2009The Emmbrook

Invisible Revealed

UV visualised inks are commonly used today, especially for security purposes. When using these inks it is vital to take consider the paper used, as many modern papers use optical brighteners, which fluoresce under UV light.

The chemicals in the ink burn at a lower temperature than the paper, however, this can easily lead to the paper burning so heating must be gentle!

Red cabbage can be used as an indicator to reveal some acidic and basic inks, however, ammonia, citric acid and acetic acid proved unsuccessful, with both the modern and chromatography paper.

Modern uses of invisible inks include security markings on bank notes, passports and driving licenses.

Tonic water

Persil detergent Milk

Chemistry Department

Outreach Team.

0.00

5.00

10.00

15.00

20.00

25.00

Tropical

Plant source Amount

(mg / 100g)

Kakadu plum 3100

Camu Camu 2800

Rose hip 2000

Acerola 1600

Sea buckthorn 695

Jujube 500

Indian gooseberry 445

Baobab 400

Blackcurrant 200

Red pepper 190

Parsley 130

Determining Vitamin C levels in fruit using iodine titrations.

Testing fruit juices

Testing whole fruitWhat is vitamin C ?

Vitamin C, also known as L- ascorbic acid, is an essential nutrient to humans . The vitamin protects the body from oxidative stress and prevents scurvy. Plants can make it themselves as can some animals, but humans do not have the right enzyme.

Iodine reacts with Vitamin C. Initially no colour change is seen. When all the Vitamin C has reacted adding more iodine gives an excess and the cranberry juice turned purple.

On titration with iodine the tropical juice/ starch mixture turned a dirty brown colour due to the colour of the orange juice mixing with the blue/ black colour of the iodine.

Natural sources of vitamin C

In our diet citrus fruits are acommon source of Vitamin C

A known mass of fruit was liquidised in a measured volume of water.The liquidised sample was filtered and the filtrate titrated with iodine solution.Among the fruits tested were apple, lime, Grapefruit and Oranges.

The results: For the whole fruits we tested Grape fruit showed the highest levels of vitamin C in it its extract.

Cranberry Tropicana Co-Op

Orange

Fruit juice Vitamin C levels

By Joshua Grant & Jacob Jolly

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Apple Lime Grape fruit

Orange

Fruit extract Vitamin C levels per gram of fruit.

Chemistry Department

Outreach Team.

Method10 cm3 of each fruit juice was pipetted into a conical flask with 1 cm3 of starch indicator solution. Each mixture was titrated with iodine solution.

Cranberry juice

Tropical juice

The results: Unbranded orange juice was found to have more vitamin C than the top brand Tropicana orange.

A titration

Filtering the liquidisedmixture

The Schools' Analyst Competition

is a national competition run by the

Royal society of Chemistry’s

Analytical Division, for first year sixth

form students studying AS level

Chemistry or equivalent.

Reading University hosts a South

East regional heat for 16 teams of

three students. The winning team from

the regional heats being entered into

the national final. The Reading heat

consisted of two tasks.

Schools Analyst Competition 2009

The second task was in

two stages. Initially the

teams used thin layer

chromatography to identify

the orange food colouring

used in Irn-Bru. This was

achieved by comparison to a

given set of standard food

colourings.

Then applying Beer-Lambert’s Law they

determined the concentration of the orange food

colouring in Irn-Bru using visible spectroscopy.

Comparing the value they obtained to the

manufacturer’s own stringent specification.The first involved the determination

by titration of the distribution

coefficient (K) for ammonia between

two immiscible solvents.

K=[NH3]a

Solvent a

Solvent b

[NH3]b

xx

Irn-B

ru

Sta

nd

ard

s

A = LogX

X

X

X

X

X

I t

I o

Concentration

Ab

so

rba

nce

I tI o

Sample

DetectorSource

This years winners were:

Abingdon school

Abingdon

They will be representing the

Southeast region, in the national

final at The University of Plymouth.

Chemistry Department

Outreach Team.

Salters’ festivals of Chemistry promote the appreciation of chemistry to young students and give them the opportunity to spend a day in a university

department. These activities are followed by a fun lecture and prize giving ceremony. Prizes are awarded to the winning teams in each challenge.

This year at Reading University, 15 Schools competed against each other in two exciting practical chemistry challenges.

Thanks to Parniyan Salar and Anne Romero, Reading Girls’ School 2009 work placement students for their help with this poster.

The SALTERS’ Challenge:Murder (?) at Saltmarsh Farm

In this activity teams took on the role of forensic

scientists, and used chemical techniques to analyse

evidence collected from the scene of a grisly crime.

Their task was to identify the prime suspects.

The University’s Challenge:Cool it ! on the Enterprise

In order to prevent the dilithium crystals aboard

the starship Enterprise from being destroyed,

the teams had to devise a chemical method to

cool the crystals to exactly 10.5oC in 1.5 minutes.

In the afternoon, teams were entertained with an exciting demonstration

lecture by Dr David Watson (Reading University). The lecture explored

temperature and featured dry ice (solid CO2 -78oC) and liquid nitrogen

(-196oC) - not forgetting the balloons, bananas, Blu-Tac and ice cream !!

Salters’ Challenge: University’s Challenge:

Queen Anne’s school, Caversham The Abbey School, Reading

Members of this years’ winning teams in action.

Close scrutiny of the university challenge was the order of the day

No shortage of volunteers – to taste Dr Watson’s Ice cream

Accuracy and precision were key as pupils examined the evidence

Chemistry Department

Outreach Team.2009

Preparation of a ferrofluid for AS/A2 students.

Synthesis of nano-sized magnetite

A ferrofluid is a stable colloidal suspension of magnetite nano-particles. These nano-particals (1 to 30 10 -9 m) become strongly polarised in the presence of a magnetic field. This

gives the ferrofluid the appearance of a ‘solid’, but they revert to their liquid state when the magnetic field is removed. NASA has exploited this technology to manipulate fluids in the

low gravity environments encountered in space.

Addition of oleic acid

causes the nano-particles

to be stabilised by less

favourable interaction

between the hydrocarbon

tails of the surface bound

oleic acid.

Before the addition of

the oleic acid the

synthesised

magnetite nano-

particles are

suspended in the

aqueous phase but

are ‘insoluble’ in

decane.

Stabilisation of magnetite nano-particles with a surfactant.

These hydrocarbon tails

enables the oleic acid

stabilised nano-particles

to be readily extracted by

organic solvents.

Interaction of the ferrofluid with a

magnetic field.

Decane

Aq.

Magnetite

Agglomeration of these

nano-particles will occur

over time, if no

surfactant is added.

This will give

aggregates in the m

size range. These

larger particles will not

act as a ferro fluid.Aggregate particle size >> 1.0 m

10-30 nm

Unfavourable

hydrocarbon

interactions

Decane

water

10-30 nm

2FeCl3 + FeCl2 + 8NH3 +4H2O Fe3O4 + 8NH4ClIron (III) chloride Iron (II) chloride Magnetite

Francesca Churchhouse, The Piggott School, 2008

Picture 1 - The decane

based ferrofluid is a low

viscosity liquid.

Picture 2 –However, in the

presence of a magnetic field

the ferrofluid is constrained

and no longer free flowing.

Picture 3 - Shows a

commercial ferrofluid in

the presence of a very

strong magnetic field, --

impressive spikes form

inline with the magnetic

field.

Add the FeCl3 solution (2 ml 2 M,

in 2 M HCl ) to the stirred FeCl2

solution (1 ml 2 M, in 2 M HCl) at

room temperature.

Slowly, over 5

minutes, add NH4OH

solution (13 ml 2 M)

using a burette.

Brown

Ferric Chloride

Green

Ferrous Chloride

Oleic acid (0.5ml) is

added to the magnetite

suspension and the

mixture heated to 90 C.

An initial brown

precipitate turns black

as the magnetite nano-

particles are formed.

This causes the nano-particles to ‘precipitate out’

of the aqueous phase. Clear aqueous phase is

visible when the nano-particles are attracted to a

magnet.

The ammonia is

vapourised, and the oleic

acid binds to the surface

of the nano-particles.

As the oleic acid is

adsorbed onto the

surface of the nano-

particles, the surface

becomes considerably

more hydrophobic.

2 31

Oleic acid

(Z)-octadec-9-enoic acid

Nano-particles

are susceptible

to agglomeration

Chemistry Department

Outreach Team.

Justice is not always black and white.

Evidence found at the scene of a crime is not always white. Forensic scientists have developeda wide range of different coloured fingerprint powders. The powder is chosen to give the bestcontrast between the print and the background. This contrast can be enhanced by irradiation ofthe fluorescent fingerprints with ultra-violet light.

Fingerprint patterns can be categorised into 3 main types.The most frequently encountered being Loops (60-70%).Whorls account for 25% and are subdivided further into:double loops, plain and central pockets. The final type,Arches, are the rarest accounting for only 5%.

These two prints have both been dustedwith the same bi-chromic powder. Thefingerprints appear dark on a light surfaceand metallic on a dark surface.

The powder binds to the oils and sweat of the latent fingerprint, but not to the underlying surface. This makes theunique ridge pattern of the fingerprint visible.

Grease, oil and sweat from fingers are transferredto the surface being touched. This leaves a latentprint, mirroring the ridge pattern present on thefinger. Latent prints can be barely visible. They aremade visible by dusting with very fine powders.

It was not until the early 1900’s that the United Kingdom Fingerprint Bureau was founded at Scotland Yard, where they pioneered the use of fingerprints in

criminal investigations. Since then, forensic scientists have worked continuously to develop the technology behind fingerprint visualisation.

Fluorescent red

Classic black on white

fingerprints.

Stephen Penney, Little Heath School and Jack Stanford, St. Crispin‘s school - work placement 2009

Fluorescent red under UV light

Fluorescent green

Fluorescent green under UV light

Metallic Gold on glass

Evidence comes in all shapes and colours, with a powder for each!

bi-chromic powder fingerprints

Held in place bysurface tension

Static charge attracts thepowder to the latent print.

Powder Adsorption

Mechanisms

Developing a latent fingerprint.

Types of fingerprint ridge pattern.

Fingerprint powders come in ‘all’ colours.

One powder two colours ?

Oily deposit left behind on a non-porous surface

Whorl ArchLoop Double Loop

Chemistry Department

Outreach Team.

Synthesis of the Analgesic: LidocaineLidocaine is a common local anaesthetic used to relieve pain and itching, injected in dental surgery and used for minor operations. Lidocaine can be synthesisedfrom 2,6-dimethyl-nitrobenzene [1] in three consecutive reaction steps: The first is a reduction, converting the nitro group into an amine. The second convertsthis amine to an amide. The final step involves the substitution (SN2) of a alkyl halide substituent by an amine to give the target compound lidocaine.

The amine attacks the polarised C-Cl bond at the carbon. The C-Cl bond breaks as the new

N-C bond forms. The chloride ion released can deprotonate the nitrogen of the amine to

generate Lidocaine and hydrochloric acid.

Step 3- SN2 Substitution of an alkyl halide.

Joseph Reed The Piggott School

Step 2- Amide bond [3] formationStep 1- Nitro Reduction2,6-dimethylnitrobenzene [1] is

reduced by stannous chloride,

Sn(II)Cl2 in acidic conditions to

form the aniline hydrochloride

salt. The initial product, 2,6-

dimethylaniline [2] is liberated

as an oil, on treatment of this

salt with a base (pH 10-12).

The rotary evaporator

removes solvents at a low

temperature by heating

the solution under a

vacuum. In addition the

solution is rotated in the

flask to increase

efficiency. In the flask is

the 2,6-dimethylaniline [2]

which was isolated using

a rotary evaporator.

The rotary evaporator

Lidocaine

The amine group (NH2)

acts as a nucleophile,

attacking the carbon of the

polarised carbonyl group in

the acid chloride.

Special thanks to Reading School pupils; Adam Wright, Daniel Rowlands & Alex Brown: for their help with the Lidocaine synthesis.

The overall yield for the three

stages was 17.9% crude and

8.7% re-crystallised. The final

step gave the lowest yield.

This step requires further

optimisation.

Analysis of the final product by accurate mass

spectroscopy, showed that a very pure sample of

lidocaine had been synthesized.

C14H22N2O

Acc. Mass:

234.3406

Det. Mass:

235.1799

2-(diethylamino)-N-(2,6-dimethylphenyl)-acetamide

This gives a tetrahedral

intermediate which breaks

down to form the new

amide [3] and release a

chloride ion.

Chloro-2,6-dimethylacetanilide

(ii) CH3CO2Na

(i) SnCl2/HCl/CH3COOH

(ii) KOH

Step 1 Reduction

CH3COOH (i) ClCH2COCl

Step 2 Amide Formation

ΔR Toluene

(CH3CH2)2NH

Step 3 Substitution

2,6-dimethylnitrobenzene [1]

70%

2,6-dimethylaniline

[3]

Lidocaine [4]

NO O-

+

N

H

Cl

O

N

HH

70%

41% crude 21% pure

[2]

Chemistry Department

Outreach Team.

Base

‡O

-

ClR1

NH2

+

R

NH

O

R1

R

Cl-

Cl

O

R1

HCl

R3

HH +

R3

ClHH

SN2 intermediate

N

H

R4

R4H

R3

Cl

H

‡