Open Day Stall Activities

Friday and Saturday saw us having a lot of fun at open day this year. We had 8 demos that we repeated many times over for scholars, kids, and the curious.

Here are a few pictures of our activities:

Thembelani showing a battery made from 3 cells using Coke as the electrolyte - we got 3 volts out of it.
So you can charge your cellphone out in the bush with coke, some metals and a bit of wire all combined with a touch of electrochemistry knowledge.

Lukanyo coverts unpleasant smelling chemicals into a pineapple essence.

Here we demo polymer science - the production of insulating foam used in fridges, geysers, and as flotation in boats.

Some inspired scholars gave Chemistry the Thumbs Up.
Now for my all time favourite...

Here we demo combustion how on can change cellulose into nitrocellulose.

All in all it was great fun for learners and staff. We look forward to next year's open day.

Your Carrer in Chemistry - Open Day at NMMU

Careers day will be held on 6 and 7 May. There will be stalls for most courses at the Indoor Sports Center at South Campus.
Chemsitry will feature there - we plan to have an interactive stall with demos including some interesting chemical reactions inside the hall. If ther weather permits we will have some more exciting outside demos including a chemical volcano!!
There will be pamphlets describing our various courses and we will have staff there who can provide information on carrers in chemistry.
Hope to see you there.

Public talk by Chemistry Professor

THE ANCIENT HISTORY SOCIETY OF

PORT ELIZABETH

PRESENTS A TALK ENTITLED

“The Romans in Britain”

by Prof Peter Loyson

Prof Loyson will discuss the Roman conquest of Britain, covering the attempts of Julius Caesar, the successful expedition of the emperor Claudius, the revolt of Boudicca, the famous queen of the Iceni, and other aspects.

The Italian Sporting Club, Harold Road, Charlo

Tuesday 3 May 2011 at 19.30 pm

Refreshments and cash bar will also be available.

Enquiries: Prof Peter Loyson 041 504 2147 or 083 359 1072

Rubber Chemistry: Part 1

Rubber! You probably first encountered it when sucking on a bottle as a baby, or later in the classroom to rub out errors in your pencil work. Indirectly we encounter rubber many times a day - perhaps most noteworthy is in getting to your destinations - tyres - they are made from rubber with additives.

Try think of 10 other uses of rubber. Do it now before your read on.......

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Perhaps you saw some rubber in the video clip of my last post - on my speargun - see it even finds use in fishing! My wetsuit kept me warm. What is it made from?

I will now cover some chemistry of natural rubber.
Man has learned to make his own rubber from crude oil, but first it was taken from plants. That is the focus of this post.
Indians in South America used rubber sourced from the sap of trees to make shoes and coat the paddles of their canoes to waterproof them - the smoke of their fires cured the rubber. Explorers and early settlers in South America saw the Indians using rubber and some were intrigued sent samples home to Europe. The industrious western mind turned such rubber into big industry over two centuries.

The milky sticky sap that is found in many plants contains some form of rubber. Just the other day I was gardening (pulling out weed creepers that entangle my garden plants). I got my hands full of sticky, yukky, white "milk". Next the soil got stuck in the sap that had lodged on my hands and my hands were a mess! Soap refused to remove it - only hot water and hard rubbing with a hot rough cloth helped remove the sticky adhesion.

What type chemistry underlies this sticky sap?

Isoprene (2-methyl-1,3-butadiene) is a common, naturally occurring organic compound with the formula:CH₂=C(CH₃)CH=CH₂

Plants produce and release large amounts of isoprene into the atmosphere. Rainforests make a huge contribution. The haze one sees on a hazy day in regions where there is extensive plant life - may be partly due to isoprene. A variety of pretty complex reactions form such hazes. I will save that discussion of atmospheric chemistry for another day. Back to isoprene...

At room temperature it is a colorless liquid but it boils easily at 34 degrees Centigrade. So it is very volatile - this explains how plants can release it with relative ease.
Isoprene is the monomer of natural rubber. Monomers are molecular building blocks from which bigger building blocks are made. Just as bricks make up walls, and walls make up buildings, so isoprene units can be linked together (polymerized) into rubber.

In biological systems such as plants, the isoprene structure is found repeated in many polymers. It occurs often as dimethylallyl diphosphate (DMADP) [click on this link for more data] and its isomer isopentenyl diphosphate (IDP). An isomer is a molecule with the same formula but a different shape or structure.

Early scientists actually extracted isoprene from rubber by decomposing it and correctly assumed that rubber was made up from repeated units of isoprene. Natural rubber, or polyisoprene exists as long chains - thousands of isoprene units bound together by the carbon carbon double bonds. Some double bonds remain in the structure of polyisoprene - these can be used to change the properties of rubber.

Charles Goodyear used sulphur to harden rubber in a process called vulcanization - where sulphur is added to rubber and it is heated to harden the rubber. Vulcanization is derived from the name of the roman god of fire "Vulcan". Volcano has the same source. Sometimes Man learns from his blunders and Charles Goodyear was such a person, he had lead oxide mixed with sulphur and rubber. Accidentally some fell onto a stove and hardened and the rest is history the future of rubber had been secured.

The long, relatively strait rubber chains (polyisoprene) are secured in position by crosslinking sulphur bonds. These bonds prevent the rubber from becoming sticky and softening with heat. A clear diagram is illustrating this in the Wikipedia definition of vulkanization. 
Mr Goodyear; yes, the same name as Goodyear tyres, he developed the vulcanization process but sadly he did not make a fortune out of it and he died a poor man in 1860. Patent infringments were problematic in his endeavours. At least his name lives on in the Goodyear Tyre company.

Now that rubber had been made hard and resistant to heat it found many uses especially in the tyre industry. Here in Port Elizabeth we have a big tyre industry where rubber is vulcanized on a daily basis in the tyre factories. 

Next time you take a drive in a car or bicycle think about the polyisoprene and sulphur that hardened the rubber that supports and carries you.


 

Cement - A swim through the Coega Harbour Wall

I took this clip some time back. I was freediving on the wall - that's my speargun you see in front of the camera. You even see a few musselcracker there in the wall.
Imagine the hydration reaction calcium aluminium silicate taking water into its structure and getting stronger - and it still continues today, even through it is very slow.

The gradual hardening of cement is a true everyday reaction.

I my next chemistry post I plan to focus on rubber and a bit of chemistry related to rubber and its use.

More about cement

Last post I showed some large scale application of cement in building a harbour wall. Cement is made from limestone and shale with other components containing aluminium and iron minerals. These are carefully mixed and heated to high temperatures with coal to form a "clinker". The clinker is then crushed and its composition is adjusted by adding gypsum to control setting times. Up to 5% of other additives may be added.
The main components of cement are 3CaO.SiO2 and 2CaO.SiO2 (tricalcium silicate and dicalcium silicate). These compounds make up the majority of the cement with the iron and aluminium clinker compounds and the gypsum making up the rest.

Cement can be made to set faster or slower by adding accelerators (e.g. calcium chloride or sodium nitrate)or retarders (e.g. citric acid, sodium gluconate).

Other additives can be added depending on the desired use. E.G. adding latex makes the cement harder and improve the workability.

When this mixture that we call cement is mixed with water it reacts with the water and sets. The reaction is called a hydration reaction, and cement can be used under water - it is hydraulic. In fact it needs the water for it to work well. Plaster is a mixture of cement and fine sand that sets hard over the brick of a wall making it smooth. If your builder is impatient and tries to speed up the drying of your cement it will be weaker, or it may crack as the water needed for hydration is lost.

When I had some building done at home my wife and the builder thought I had gone insane when they found me perched on the wall watering it with then garden hose! I wanted it hydrated.

Some times you may see concrete (cement and large pieces of stone and fine sand mixed) being covered with plastic or wet rags - these cover remain on for 48 hours - this allows the hydration to further strengthen the cement or concrete before it dries. Actually cement gradually gets stronger the longer it stays wet - the strength will double from 8 hours to three days and after another 27 days the strength will double again.
From this you can see that the impatience of builders to complete the job can lead to weakened structure.

Here is a chemistry based tip for you if you build. Keep an eye on the builder and staff - they should only mix as much cement as can be used in 1 hour (the cement bag normally reminds them anyway - printed user-directions). Do not let them mix the cement sand and water just before lunch. The cement gets started reacting and the hydration reaction is well under way while they rest in the shade for that hour or so - your structure ends up being weaker if the builder violates this procedure. Two years later your plaster is falling off the wall and the builder is long gone. The same goes for tile adhesive and grouting  as these materials are also cement based.

Cement is stronly alkaline - in the manufacture the limestone breaks down to carbon dioxide gas and calcium oxide rendering it alkaline. Some alkalinity is released during hydration as well. Keep cement off your skin or it will slowly dissolve your skin.

Fact: Did you know that you can make lime Ca(OH)2 by heating sea shells or egg shells to 850 deg C?

Cement reacts with water and give off heat at the same time - in the building of large concrete structure water cooled pipes may be included to prevent cracking of the structure.

So there you have a bit of everyday chemistry - we rely on the chemical reactions of the past for our structure of the present. There is more water in your walls that you may think.

Where did you go today? Any chemistry involved?

Last week after I wrote that post I climbed into a helicopter at the PE airport and headed north east.
An internal combustion engine got me there - that combustion involved the reaction of fuel consisting mostly of carbon and hydrogen (hydrocarbon) with air which contains oxygen.
During the combustion the carbon in the fuel forms carbon dioxide. Possibly carbon monoxide will form as well, and hopefully no carbon(black smoke). The hydrogen combines with oxygen from the air to form water. Along with these gases - carbon dioxide and water vapour - comes a lot of heat. The hot gases are what drive the 4 cylinder engine in the small chopper I went up in.

Now being off the ground and a bit closer to the sun I thought of the ozone layer.

Ozone, (O₃)  is a form of oxygen that is unstable and readily reverts back to oxygen ( O₂) as we know it, and breathe it. It has a short half life - about 30  minutes. That means the concentration drops by 50% in 30 minutes. Higher up in the atmosphere (10 -50 km up) energetic radiation from the sun can break normal oxygen apart to form two free oxygen atoms that are reactive. These can then react with another normal oxygen atom to form ozone.

    O₂ + light = 2 O.  

     O  +  O₂  = O₃

This is how ozone forms in nature. The ozone layer protects us and other life forms from UV radiation by absorbing most of that harmful light. Click here for a link to how ozone is distributed in the atmosphere.

Lightning can also split apart oxygen allowing it to form ozone.
We can make ozone using sparks in a corona discharge tube. Air (or pure oxygen) is pumped through the tube and an air ozone mixture comes out.  A strong UV light will also make ozone.

Ozone is used mostly in water treatment for drinking, swimming pools, of aquaculture.  It kill bugs or oxidizes unwanted pollutants.

So that is a bit of natural chemistry (photo chemistry) that happens each day, and saves our bacon in the process. Look up, and imagine the ozone formation, or next time there is a fine electric storm - imagine the lightening forming ozone.


Now back to my flip in the chopper. About 12 km northeast of the airport I looked down at the Coega harbour.

Now there's is a big project that involved plenty of chemistry.
Obviously a lot of fuel was burned to build that wall.

Each of those dolosse (wave breaking structures) lying down there on the sides of the wall weighs about 30 tonnes. That's a lot of cement used to make the concrete!


Ah! yes, I have walls around me now, and you probably do too. Mostly these walls are made of brick and cement.

What is cement?

How is it made?

How does it get hard? Does it dry? My builder says yes, in fact he wants it to dry fast so he can paint and get on with the next job.

What does the chemistry suggest? Dry it fast?

In a subsequent post I will talk about cement manufacture and setting ; and perhaps we can have a closer look at the Coega wall - I will take you into the wall, and under the water...

Every Day Chemistry

There are some aspect of chemistry we experience every day.

Can you think of some everyday chemistry - outside of your body, that is?

Let me ask a you few questions:

1. Where did you go today?

2. What chemical reactions took place to get you there while you travelled?

3. What place/s did you visit?

4. What chemistry took place to build that place, or to decorate it?

Take some time to think about it and I will cover a reaction or two in my next post.

I will leave you with though video clip. It is a though provoking talk by Thomas Thwaites entitled: "How I built a toaster -- from scratch"

Enjoy.....

Your elemental composition and a few interesting facts

Your body consists of about the following:

• 65% Oxygen
• 18% Carbon
• 10% Hydrogen
• 3% Nitrogen
• 1.5% Calcium
• 1% Phosphorous
• 0.35% Potassium
• 0.25% Sulfur
• 0.15% Sodium
• 0.15% Chlorine
• 0.05% Magnesium
• 0.0004% Iron
• 0.00004% Iodine

There are obviously considerable variations from person to person. Ladies differ from men - for instance men are true iron men in that they contain 1.65 times as much iron as ladies.

Also, there are traces of other elements but the above list covers the major components.
The elements are combined in many, many forms.
That's what chemistry and biochemistry are about.

What would happen if you took this amount of each of these elements and mixed them - enough to simulate a 70 kg person?
Reactions would begin right away - quite likely causing heat. If you added a spark to this combination it would explode, then burn and smaller violent reactions would be seen.

Would it validate the "Big Bang Theory"?

Well, maybe on a smaller scale.
You certainly would not end up with a human! If you were patient and could wait a few million or billion years perhaps those mixed elements would evolve into some lifeforms. A nice thought, but I do not have the time. Still it would be fun to look at combining many of those elements and studying the reactions - putting equations to them - a topic that can be covered in future posts.

Now let's get back to the composition of humans:
Our bodies are a more delicate combination of these elements - lots of water, a good bit of protein, fat and bone. Sugars can be found  in our blood, as well as oxygen, carbon dioxide and many more compounds, all made of systematically arranged elements, or molecules, which are arranged in bigger groups such as cells, which again are arranged to create organs, which make up the physical form of mankind and other lifeforms.

Even the air in our lungs is part of our make-up - nitrogen and oxygen for the most part.
How much air do you contain? We would need to know your lung volume - if it is 5 liters then you have about 6 g of air (1.2g per liter x 5 liters) .

Of that about 21% or 1.26 g is oxygen. It seems so little. Think of the freedive world record holder, Herbert Nisch, who descended an incredible 214 m strait down into the ocean on a lung volume of about 12 liters (~3 g of oxygen). That is a 428 m round trip on 3 grams of oxygen - rather efficient, I would say. Yet we humans are terribly inefficient oxygen conservers compared to seals and other marine mammals.

So, physically, humans and animals, are complex combinations of elements. All the elements in the above list can be analysed for and many of their combinations (or molecules) can also be analysed using analytical instruments and other chemical means.
In recent years many simple instruments used to analyse such molecules have been developed - for example we could analyse Herbert Nisch's blood using a pulse oximiter (oxygen meter) just before he dives by clamping a small noninvasive device to his fingertip or earlobe - it reads the colour of his blood in time with his heartbeat - the redder the more oxygen, when he surfaces he is definitely close to passing out because he depleted a lot of that 3 g of oxygen that he took down with him. Now the clip-on oxygen meter would read a much lower level. The red colour readings must be made at a consistent time in his pulse cycle because with each heartbeat because the little capillaries in the fingertip or earlobe actually expand with each heartbeat and would give more red at the time of a pulse rather than after the pulse when they shrink.

On the topic of blood, the red colouration comes about from haemoglobin, the oxygen carrier that transports oxygen from the air to our bodies. If you train hard for an event, perhaps the Iron Man, or deep freediving as in Mr Nisch's case, the haemoglobin levels in your blood will change. They must, so as to cope with the hard work (oxygen starvation). Your body builds up more haemoglobin in the blood - that is one of the key parts of training for such an event. I do some freediving as a hobby. After extensive long duration dive sessions I find running to be extremely easy as compared to normal - it is surely related to the boost in my haemoglobin levels thus making oxygen transport efficient and the run becomes easy.

So chemistry is involved in getting fit too. So why not go do some chemistry on the sports field after work or school - you cannot escape it even if you try, so rather become more aware of how you do it...

One of my former Lecturers, Prof Peter Loyson, regularly suggested that we imagine that we have been shrunk down to molecular size and imagine what the molecules look like and how they interact with each other - we often used to laugh at this concept, yet strangely enough I find myself doing exactly that - trying to picture what is going on. You even see it shown in some movies these days - the film simulates an activity in the blood or muscles.

Hey! It is The International Year of Chemistry so why no try it out...

Imagine you are an observer in you blood stream, lung surface, or even inside an egg you are cooking.

What is going on in your internal organs and "plumbing"?


p.s. If you wish to see a lot more detail of what blood consists of click on the link.

Elemental Analyses - Video Clip Showing Flame Colours

In the previous post promised I would explain how one can use flame colours for analysing elements.

Just as we all have finger prints, DNA, irises etc. that can be used to identify us, or to catch criminals, so each element has its own characteristics that we can use to track it down.
You saw the flame colours in the previous post - those are specific characteristics we can use to find out if an element is in a sample, be it beer, metal, or a carrot.

To analyze we would have to get some of the sample into a flame to free up the elements and allow them to emit their specific colour of light. In simple mixtures and pure compounds this method gives us a way to ID a few elements. In more complex cases we need the help of instruments.

When heated sufficiently most elements actually produce a range of colours and some colourless ultraviolet light. We can use devices such as prisms to separate the light and then use a very sensitive device to measure how much of each specific colour (or wavelength) of light there is in the flame(an the original sample).

There are many different types of instruments that use flames, microwaves, or even arcs, sparks or plasmas to make a cloud of atoms. In the iron and steel industry, for instance, there are arc instruments that make a continuous arc (similar to electrical welders). The arc vaporises some of the metal being analysed and it emits light according to its elemental makeup. In a short space of time the instrument separates the light using prisms or gratings and measures how much light there is of each colour or wavelength - from this information we can get a report of the amount of each metal or other elements that are in the sample being analysed. Its really quick - back in the old days it took perhaps a few days to get the same result using other chemical methods.

In our Analytical Chemistry Course students make use of many simple and complex instruments for analysing elements. Some of these instrument may cost as much as 1.5 million rands or even more depending on complexity and technology.
I asked my 3rd year analytical students to give a brief demo of how these flame colours can be used in analyses on a flame instrument. Its their first filmshow, Take #1
Let's see what they have to say...

Thanks for that Ludwe and Luzuko - not bad for the first attempt.

That instrument was a flame spectrometer with an air acetylene flame at about 2400 DegC into which they fed copper and strontium dissolved in water.

Next post I want to talk about Your elemental make-up.

Till next time,

Gletwyn

The International Year of Chemistry, and You

Welcome to this blog.
It is an honour as well as an exciting moment for me to type these words as this is the international year of chemistry. I have been formally in chemistry since the day I left school back in 1986, however, that spark which ignited this passion for chemistry flashed many years earlier, in about 1974.

Let me quickly tell a little story.

At the age of six my family gathered around the fire one November night under the Karoo sky. My dad ignited some fireworks, while we qualified to hold sparklers.
For myself and my twin brother this was pure delight. 
Soon the last firework was spent and my hopes dimmed from the exciting flashes and bangs.
From that moment on, the desire to see of these spectacular flashes once more burned with ever increasing brilliance and I turned excitedly to Encyclopaedia Britannica, my twin brother alongside. Farmer dad and ballet teacher mom could not help us much so we had to do it on our own. We did, the slow way. Many years, and hundreds of experiments later I created my own fireworks, rockets and tremendous bangs which far exceeded the normal home fireworks - this was in my seconds year of studies in Analytical Chemistry at the then PE Technikon in 1987.

Seemingly small events made big changes in my life and steered my interest. This happens to You too. I was fortunate to be taught by Padre Dixon at Union High school in Graaff Reinet - he was tremendously enthusiastic and was always doing chemistry and physics demos for us.

Unfortunately many schools are crippled by budgets that do not permit young potential scientists the opportunity to learn by seeing the thing they are learning about. I find this all the time when lecturing students and it saddens me.
What can be done about it? Occasional visits by university staff to schools are possible but there are many schools and time does not permit.

Being the International Year of Chemistry I thought it fit to begin to use the tools we have in this modern world to bring chemistry to you in the form of this blog site. It is called Chemistry and You for a good reason. Chemistry affects you and everyone else far more that we may realize.
My fellow staff and I am going to bring you a lot of chemistry in the form of short posts, pictures, video clips on Youtube (yes, you can see what we do in the labs). Also we will use social media such as Twitter and Facebook.

I am Dr Gletwyn Rubidge of the Nelson Mandela Metropolitan University, I look forward to making regular contact with you.


Now let us waste no time and get on with it...

I spoke about fireworks kindling my interest in chemistry.

You have surely all seen fireworks.

Ever wondered what makes them work - what makes the colours, the bangs, the smoke?

Colour in Fireworks:
I set off three 1000 foot flares at a new years party - as you can expect my 7 year old son loved it. One question he asked me was how does it get to be so bright red.
I explained that it is a type of gunpowder inside the flare that burns very hot (about 3000degC) and it has an element called strontium in it. The heat causes the atoms to become free - kind of floating about. Normally the atoms are bound to some other atom but at this temperature they are mostly separated from one another. In this free state the outer electron in the atoms can get excited and moves to a higher energy state. Kind of like you climbing up to a branch in a tree. When it calms down or relaxes it can release energy as light. Strontium can release red light as it relaxes back to the lower energy state.
Yes, you guessed it, that red light you see is from strontium added to the gunpowder in the flare.

Here I put some strontium into an air acetylene flame at about 2400 deg C - normally light blue like a gas stoves blue flame - the strontium makes the flame a strong red colour.

How do they make green?


Barium gives a light apple green colour.

Sodium gives an orange-yellow - the same colour you see in some of the street lamps such as in Target Kloof, PE.
Have you ever seen some water boil over from a pot onto a gas stove - the blue flame goes yellow. It is mostly sodium light you see in that flame.

Potassium yields a lilac colour.

Calcium forms a brick red colour

Copper forms a blue-green

In my next post I will cover how we can use these colours for analysing these elements and many more.