The Science of Fire

The use of flint and steel to make a spark ('Dragons Breath')

John Walker was the first person we know who invented the friction match. He called his invention the 'John walker's Friction Light'. This extraordinary invention was dated 1827 but what did we use to light fires before this time? (BBC).

Before the invention of the match people would use flint and steel to light their fires (Practicalsurvior.com - Reference) In the first uses a piece of harden steel would be struck against a sharp and hard edge of the flint (Bricevskis). Flint and steel kits can be bought today with the traditional steel striking the flint (Munilla) and the flint striking the steel (Sicree).

Taking a closer look at the science of flint striking steel an understanding of what is happening to create the sparks must be met. When the hard edge of the flint is struck against the steel, little pieces of steel are separated from the main rod of steel. Due to the friction of the flint on steel, heat is given off and this is used to ignite the little pieces of steel (Bicevskis and Gerke). So why do we need all this energy in terms of heat and why the need for such small pieces of steel? A look at the bigger picture of steel will be needed.

When cutting longer pieces of steel, it must be pre-heated to 870 Degrees Celsius before being 'blasted' with a high purity oxygen stream; this then cuts through the steel. This process shows that oxygen readily reacts with the steel (Michael D. Lanyi, 2000). This shows the extraordinary lengths people and companies go through to cut large pieces of steel to shape. Therefore it must take a lot of energy to ignite a block, slab or rod of steel; because of high temperatures needed and high levels of oxygen a different approach is needed. The ignition temperature is dependent on several variables: density, surface area and humidity. There is a possibility of increasing the surface area of the steel to reduce the ignition temperature needed  to ignite the steel. This is achieved by producing small pieces of steel created when striking flint against steel. Due to the reduced surfaced area the small pieces of steel are easily oxidised and thus pieces of steel are ignited (Munilla).

This is how a spark can be created with flint and steel.

-Below is a video clip showing steel being struck by flint (in slow motion) to produce small pieces of steel, which ignite to give what we know as sparks (The Slow Mo Guys, 2012):

http://www.youtube.com/watch?v=qO9g1_BTz0o

Bibliography

BBC, Contributed by Preston Hall Museum and Park. John Walker's Friction light.
Available at: http://www.bbc.co.uk/ahistoryoftheworld/objects/hQR9oN5LTeCLcuKfPDMJ9A
(Accessed: 11th March 2013)

Bicevskis, R. Flint and Steel Notes - Some Clarifications.
Available at: http://www.wildwoodsurvival.com/survival/fire/flintandsteel/RBclarifications.html
(Accessed: 16th Feb 2013)

Gerke, R. How to start a fire using flint and steel.
Available at: http://www.humankinetics.com/excerpts/excerpts/how-to-start-a-fire-using-flint-and-steel
(Accessed:16th Feb 2013)

Michael D. Lanyi1, “Discussion on Steel Burning in Oxygen (from a Steelmaking Metallurgist's Perspective),” Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Ninth Volume, ASTM STP 1395, T. A. Steinberg, H. D. Beeson and B. E. Newton, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000. [online]
Available at: https://www.airproducts.com/~/media/Files/PDF/industries/metals-discussion-steel-burning-oxygen-steelmaking-metallurgist-perspective.pdf
(Accessed at 11th March 2013) 

Munilla, R. 'Flint and Steel Fire Starting' Partical Survivour [online]
Available at: http://www.practicalsurvivor.com/flintandsteel
(Accessed: 18th Feb 2013)

Sicree, A, a, Ph.D. 'Fire From the Rock', "Minerals that do things...", p1 Hands-on demonstrations of mineral properties [online].
Available at: http://www.mineralseducationcoalition.org/pdfs/Fire_From_Rock.pdf
(Accessed : 17th Feb 2013)

The Slow Mo Guys (2012) Flint and Steel at 5000fps.
Available at: http://www.youtube.com/watch?v=qO9g1_BTz0o
Accessed (9th Feb 2013)

Science of Cooking

What do we mean by cooking?

Well, the free dictionary (2013) states that cooking is ‘the act of preparing something, often food, by the application of heat. This sounds simple enough but what does that actually mean?

We know that if you increase the temperature inside an object that the molecules begin to behave differently, whether this is by moving quicker or even vibrating faster. This leads us to our first theory on why food changes during cooking. From a biological view point, denaturation occurs in organic molecules, for example, proteins when they are greatly heated. A strong example of this is in eggs where the protein albumin is present. This protein is soluble in water which is why the egg seems clear in water. However, when this protein s heated, the tertiary and secondary structure of the protein starts to bend, vibrate and twist. These movements cause the hydrogen bonds between the structures to break, this in turn effects the larger structure of proteins and cause them to become denatured. By having the protein denatured, the active sites on the proteins structure are now all but useless and so the proteins properties change, and in the example of albumin, it becomes an insoluble, solid, white mass. (Chemistry explained, 2013) This shows us an example of an irreversible cooking reaction.

Bibliography
 

Chemistry Explained, n.d. Denaturation. [Online]
Available at: http://www.chemistryexplained.com/Co-Di/Denaturation.html
[Accessed 10 3 2013].

 

The free dictionary, n.d. Cooking. [Online]
Available at: http://www.thefreedictionary.com/cooking
[Accessed 10 3 2013].

 

The Science of Chalk

The Science of Chalk

What is Chalk and how is it formed? 

Chalk is a white, grey or yellow limestone formed mainly out of calcium carbonate, CaCo3 in the form of the mineral Calcite. The chalk is formed under water, on the sea bed when there are the correct conditions for the process to take place. It begins as being lime mud which undergoes a series of geological processes which involve heat and pressure removing the water and compacting the mud turning it from a sediment into rock. The process of compression is known as diagenesis. The lime mud itself is formed from the skeletons of plankton that fall to the bottom of the sea bed. 

Most chalks come from the Cretaceous period ( 145.5 Million to 65.5 Million years ago), this is because during this time there were high global temperatures and sea levels due to the break up of the super continent Pangea. The break up of the continent led to magma rising from beneath creating a new sea bed and mid ocean ridges swelled and water was displaced onto the continents by the magma spilling out onto the rest of the sea floor. Then in the sea ways of the flooded continents the chalk was made. 

The Cretaceous chalk is white, why is this? 

The chalk gets its white colour from the skeletons that it is formed from, because they are mainly colourless as is the case with many limestones. The Cretaceous chalk is very white because when it was formed the sea levels were so high that this prevented the chalk from gaining impurities and as the sea floor was very active any organics would have been broken down very quickly.  

Where can the chalk be found?

There are many places you will find chalk. Some of the oldest chalk deposits, formed in the Cretaceous period, are situated in Sweden and England, such as the chalk cliffs of Dover. Some other large deposits are in the USA going from south Dakota, southwards to Texas and eastwards to Alabama. 

In England the chalk runs between Devon and Yorkshire and many of the counties on the South East. There is also chalk underneath London, the North Sea and the Channel. There are three parts to the chalk formation in England, The Upper Chalk, The Middle Chalk and the Lower Chalk. 

What can be found in the chalk?

There are many fossils to be found within the chalk, especially as the chalk itself is made up of plankton skeletons. Commonly found fossils include; bi-valves, echinoids, ammonites, bryozoans and sponges and most of them have been preserved very well by the chalk. It has also been known to very occasionally find preserved fish, starfish and crustaceans, these have been proven to show occasions where the chalk has been transported down a slope and to bury the creatures which were on the sea floor alive. As well as fossils there are other materials that can be found within chalk an example of this is Flint. 

Uses of Chalk

When it comes to uses of chalk many people would immediately think of the stick of chalk used to write on blackboards, however these days that chalk is made from synthetic materials. There are still however many uses for chalk. 

• Chalk is used to raise the ph levels in soil with high levels of acidity in agriculture. 
• To enable toothpaste to have a slightly abrasive effect chalk can be added.
• Chalk with very carefully measured grain size is often used for polishing. 
• Builders putty contains chalk as a filler. 
• Chalk is used in antacids, which when small doses are taken orally help to neutralise stomach acidity. 
• It can be used to enable athletes, such as gymnasts, to have more grip.
• When heated the chalk will turn into lime which can be used for many things such as the production of steel and glass. 
• Chalk is added to make cement mix.
• Chalk is also used as a whitening agent in paint and cosmetics. 

The Channel Tunnel

The channel tunnel goes from Kent all the way under the channel to France. It goes through one particular layer of chalk which is called Chalk Marl. Here is a diagram to show this;

Image from: http://www.tunneltalk.com/Channel-Tunnel-Dec10-20-years-on.php

Why Popcorn Pops

Why popcorn pops? (The Popcorn Board 2011)

The three main elements as to why pop corn pops are:

1.     The percentage water content within the popcorn seed.

2.     How hard the shell of the popcorn is, and how in tacked the shell is.

3.     How starchy the centre of the popcorn is.

Popcorn is a type of maize, which is part of the grass family. There are three parts to the popcorn seed.

1.     The germ

2.     The endosperm

3.     The pericarp

 

Available at: http://analytical.wikia.com/wiki/Endosperm(Accessed: 6^th march 2013)

The most important part of the popcorn is the pericarp. The pericarp is the perfect thickness so that it protects the germ and the endosperm from damage but is also the perfect thickness so that it can burst open.

Popcorn contains a small amount of water. The overall water percentage of the whole seed needs to be just below 14% for the seed to be able to pop. This is because the water needs to be heated up within the seed to ‘pop’ the popcorn. When the water reaches 212°C the water turns to steam. This would normally happen at 100°C but because of the pressure within the seed, the temperature has to be higher to boil the water. The pressure inside the popcorn reaches 135 pounds per square inch (what makes popcorn pop 2012) after the water has boiled.  The starch within the centre of the of the popcorn starts to expand and cause the foam to form in airy bubbles. The bubbles solidify together and rapidly cool off (Daven Hiskey 2010)

D, Hiskey. (2010) Why popcorn pops. Available at:

http://www.todayifoundout.com/index.php/2010/07/why-popcorn-

pops/ (Accessed: 10 February 2013)

What makes popcorn pop (2011) Available at:

http://www.popcorn.org/ForTeachers/TeachingGuide/WhatMakesPopcornPop/tabid/88/Default.aspx (Accessed: 9 February 2013

The Popcorn Board (2011) Why popcorn pops. Availible at: http://www.popcorn.org/ForTeachers/TeachingGuide/WhatMakesPopcornPop/tabid/88/Default.aspx (Accessed: 9th February 2013)