Chromatography 17.3

Describe how you have carried out a chromatography experiment. [P4]

Aim

• Use chromatography to analyse pigment from leaves.

Method

• The leaves are cut into small pieces and deposited into the mortar.  A small amount of sand is then added to enable the grinding process. Propanol is also added.
• A pencil line on a strip of chromatography paper is drawn 2cm from the bottom.
• A capillary tube is used to collect a small sample of the resulting mush made from grinding in a mortar leaves, salt and propanol.
• The sample is deposited on one point on the pencil line, and then the paper is inserted into a boiling tube filled with around 1.5cm cube of propanol.
• The result are observed and noted.

Results 

Spinach leaves:                       Results

Pigment – 5 cm                       5/6 = 8.3

Propanol – 6 cm

Y leaves:                                    Results

Pigment – 1.5 cm                   1.5/6 = 0.25

Propanol – 6 cm

Class results (spinach)*

0.5/0.6

0.81

0.84/0.41

0.67

0.72

0.75

*Each of these results were obtained independently from ours i.e. they were six groups of 2 students whose results are listed above.

Conclusion

From our results we found that the spinach leaves dissipated much more than the y leaves, indicating that the pigment from the spinach leaves has a much higher retention factor than the y leaves.  Thus using propanone is it will be easier to remove the spinach pigment if it were in the form of a stain as in described by the scenario.

Demonstrate how chromatography works, including specific details as to what would happen if two pigments matched up.[M4]

Chromatography is used to separate mixtures and identify the different colouring agents found in chemicals. In order to achieve this, the chemicals or mixtures that one wishes to use are deposited onto a filter paper and introduced to a specific solvent that is able to dissolve and carry the different dyes of the mixtures along the filter paper.

Source & all credits to: http://www.gcsescience.com/e8-chromatography.htm

In this illustration we can observe that the solvent has moved up the filter paper and separated the dyes from the original mixtures, in this case ink spots. We can see that the separated dyes have travelled a certain distance; the blue colouring agent has travelled 4 units, while the solvent has travelled 10 units.

The ratio between the colouring agent and solvent limit defines the retention factor.

Blue spots –    Retention factor = Distance travelled by coloured spot

(divided by)

Distance travelled by propanone

Rf: 4/10 =0.4

The solvent carries the dyes up to a certain distance on the filter paper, the distance travelled will indicate what kind of pigment is present. For example if two mixtures both have the same kind of pigment, using the same filter paper, both dyes will be present on the filter paper at the same distance from the solvent limit, indicating that they are the same pigment. However similar dyes will not denote the same feature, they will travel different distances thus indicating that they are different dyes, however similar they might appear.

In conclusion, chromatography separates materials by using a solvent which carries the different dyes or colouring agents present in a specific mixture. The distance travelled by each dye indicates their pigment and retention factor. By using these known properties one is able to clearly identify pigment prevalent in mixture.

Suggest problems with a simple chromatography and others methods (of chromatography) which might yield more reliable results. [D4]

Gas chromatography

Gas chromatography can be used as a tool to analyse the components of compounds by vaporisation without harming or decomposing the compounds in any way. The compounds can be separated in order to analyse the components, a relatively common process in analytical chemistry. Gas chromatography does not stop there however; testing for purity of a particular substance is also commonplace.

This type of chromatography, although similar in its aims and process, does differ from other types such as column or thin layer chromatography in that the process of separating compounds is carried out from liquid to gas.

Advantages 

• Requires only very small samples
• Can separate complex mixtures into individual components effectively
• Unlike other types, the results of the analysis can be obtained fairly fast.
• It is able to detect very minute volatile mixtures unlike other types.

Drawbacks

• One of the major drawbacks is without a doubt its usefulness on substances which would be harmed if vaporised and would start to decompose should the temperature become too high, furthermore the compounds used must be able to become volatile without being harmed.
• Once the samples have been separated they cannot be used again for further analysis.

Thin layer chromatography

Similarly to paper chromatography, it uses a type of medium such as plastic or glass coated with an adsorbent material. The compounds or mixtures are deposited on the medium that has been coated and a solvent is introduced, this is known as the mobile phase as the components of the mixture start to separate.

Advantages

• It has quite a few advantages over paper chromatography these include;
• Speedier results, greater sensitivity in recognising compounds from mixtures, a smaller sample requirement and a greater variant in the available compounds to use without damaging the plate.

Disadvantages

• The results can sometimes be faint, the separated components can sometimes cause streaking, and the solvent used can have an uneven line at its limit.

Paper chromatography

This is one of the most basic of ways with which to separate components from mixtures, by simply depositing a sample of a mixture on filter paper and introducing a suitable solvent, the components can be analysed fairly easily to a rudimentary level.

Advantages

• It is one of the cheapest and easiest ways to perform a chromatography. It requires a very basic kit of tool which is cost-effective and easily obtainable. The knowledge required to perform a paper chromatography is very basic making it the simplest around.

Disadvantages

• In comparison with other types of chromatography is quite slow in obtaining a result. It is also unable to analyse complex substance, due to the nuances that must be obtained for the
• may harm it has made it quite redundant and impractical to use in the modern world.

Conclusion

Gas chromatography will in my opinion be the method that will give the most precise results consistently. It is able to identify extremely precise results of minute samples, a feat that none of the other chromatography techniques I have described can achieve. This is what makes gas chromatography so much more valuable in an environment which requires precision and consistent data. However it does have a major drawback and that is its inability to analyse certain chemicals due to their very fragile state, which would be harmed during the analytical process. Still, it is an invaluable piece of technology and has its place alongside other devices that are able to analyse the chemicals gas chromatography can’t.

Organic compounds (ester) 4.2

Prepare a presentation around an organic compound of your choice, making sure to include important details as to its use and current role in the world.

What is an Ester?

• ›They are organic compounds derived from oxoacids (acids containing oxygen) and hydroxyl compounds (Oxygen and hydrogen bound together).
• ›For example Pentanol and butanoic acid is reacted in order to form pentyl butanoate which creates the smell of strawberries.

Uses of Ester

• ›Perfume
• ›Sweets
• Ice cream
• Soap
• Softeners in moulding and plastic industries
• Therapeutic (counter-irritant)

Properties of Ester

• ›Sweet smell
• ›Artificial flavouring
• ›Non toxic
• ›Does not irritate the skin
• ›Volatile (evaporates easily)
• ›Insoluble in water
• ›Does not react with water

Uses in perfume

• ›Perfumes are applied in the skin therefore it is important they do not irritate or poison the wearer.
• ›A perfumes fragrance is accentuated by Esters thanks to their sweet-smelling properties.
• ›Since it is volatile, perfume molecules reach the nose effectively.

Hazards, risks and disadvantages

• Perfumes are tested on animals before human trials this is due to chemical arrangements sometimes causing adverse effects to the wearer.
• ›This raises ethical concerns on whether perfumes and pharmaceuticals should be tested on animals to decide if they are safe or not.

Importance of Ester

• ›Ester is a very useful substance in terms of beautification.
• ›The fundamental essence of attraction is driven by the use of perfumes and therapeutic treatments which all strive to emulate pheromones. In fact many species of both fauna and flora use artificially created scents to attract the opposite sex or pollinator.

Understanding & describing types of energy 2.1

Task 1 – Make a careful note of result and conclusions. Describe the energy transformation [M1]

This assignment involves studying various activities in a lab and describing their energy information.

1. Describe the activity [P1]
2. Describe what happens.
3. Write the energy transfers.
4. Explain the transfer [M1]

Shake the box (Chemical –> Kinetic –>Sound)

When you shake the box, kinetic energy is applied; this energy is transformed into sound as the contents of the box bounce of the cardboard sides.

Efficiency: Some sound energy is lost but the device remains somewhat efficient.

Bench lamp (Heat + Light (solar) –> Electricity –>Kinetic –>Wind)

The lamp represents the Sun, as it produces heat and light the solar panel transforms that energy into electricity which powers the wind turbine which transforms it into wind power.

Efficiency: Considering that the solar panel does not make any use of the thermal energy of the lamp and it not even capturing all of the light, it is not a very efficient use of the lamp. However for the experiment if you consider the lamp to be the Sun, then yes it is very efficient since the Sun is a free resource on our time scale. This is without considering whether or not the conversion rate of light energy into electricity and then wind is at its optimum.

Pendulum (Potential –> Potential  –> Kinetic)

When the pendulum swings to the right, gravitational energy is used as it is attracted back to the ground and potential energy is used to swing it from side to side.

Efficiency: Considering that there is virtually no wasted energy apart from the resistance created by air which slows the pendulum down, if based on only that then it is efficient.

Metal bar that spins (Electric –> Kinetic + Sound +Potential)

Electricity is fed through the generator which transfers it to the mechanical system that allows the bar attached at the end to spin which in turns transfers potential energy to the string and piece of metal attached to it, making them spin. Sound energy is also lost during the process.

Efficiency: Sound energy as well as a very small amount of heat generated by friction is lost, the system is somewhat efficient.

Wooden car (Chemical –> Kinetic –> Kinetic + Sound)

As you push the wooden trolley, kinetic energy is used and as the trolley moves along the floor, as the wheels turn they transform this energy into sound and kinetic energy.

Efficiency: Only sound energy is lost, it is fairly efficient.

Kinetic powered lamp (kinetic –> Electric + sound –> Light +Thermal)

Kinetic energy is used to generate electricity through a dynamo that transfers the electricity to a lamp. The lamp transforms that energy into light and thermal energy.

Efficiency:  Sound and thermal energy is wasted from both the dynamo and the lamp, but more energy is used than lost, it is efficient.

Solar powered mechanical system that turns (Solar power –> Electricity –> Kinetic)

The lamp represents the Sun and as it generates heat; it powers the solar panel which will transfer electrical energy to a mechanical system that uses kinetic energy to spin a metal bar.

Efficiency:  A very small amount of sound and heat is lost; it is very efficient in that almost no energy is lost during the transfers.

Metal Coil (Kinetic –> Potential –> Kinetic + Sound)

Kinetic energy is used to pull back the metal coil and transforming it into potential energy until it is released, at that point the energy will be transformed into kinetic and sound energy.

Efficiency: Sound energy is lost in the process, this is the only energy wasted as such the system is efficient.

Flywheel (Electricity –> Kinetic + Sound –> Potential + Sound)

Electric energy is used to power the chain around the device; the energy is transformed into kinetic, potential and sound energy when released.

Efficiency:  Sound energy is lost in multiple areas however the system is efficient because less energy is lost than used.

Task 3 – Explain how the energy losses due to energy transformation can be kept small so they do not affect the environment, when you design your new building. You must justify all your energy conscious decisions. [D1]

Energy losses can be kept small with the help of simple and complex ideas alike that reduce energy transformation, thus reduce energy consumption and increase energy efficiency.

Energy is neither lost nor created, it is simply transformed. This is paramount to understanding how energy efficiency works. Energy is needed to power, heat up and maintain buildings. By using techniques to reduce the amount of energy that is wasted i.e. transformed into something we’re not actively using, we can increase our efficiency and reduce the amount of energy we need, helping to shape a greener more sustainable future.

New building proposal:

The new school building will be built with green in mind; as such I will try to demonstrate the plans we have to achieve this. The first part of the project will be the design of the building, we want to it to blend within the environment without compromising on utility or aesthetic.

In order to achieve maximum energy efficiency and minimal environmental damage, we are going to implement these features in the new building:

• Green walls & roofs
• Insulation
• Photovoltaic windows & panels
• Power generating floor (main room e.g. hallway)

Green walls & roofs

Planting fauna on the walls and roof will reduce heat loss and thus energy consumption during winter and help decrease the amount of heat the building takes in during summer months. This is due air being trapped between plants and walls, similar process through which energy efficiency works with double glazing. It also increases the life span of the roof and helps to insulate the building for sound.

Both green roof and walls will in addition to the benefits mentioned above; help create a better environment by reducing CO2 levels and providing a habitat for insects which in turn provides food for other species such as birds. Increase the life span of the building by protecting it against environmental damage such as rain and hail provides a pleasing aesthetic feature.

Photovoltaic windows & Panels

These are translucent windows which can harvest solar energy just like solar panels and they can provide around 80-250 watts each, as an additional benefit they also reduce the amount of heat going through thus reducing the need to cool the building and they provide 100 % UV reduction and infrared radiation.

These are solar panels which will be set up on multiple key points on the roof, all of which will be able to direct themselves at the sun in order to get the maximum amount of solar energy possible.

Power generating floor

These floors will be set up in high traffic areas, as pedestrians walk they will generate electricity by exercising a force on the material the floor are made of. These materials have a specific property which allows them to create electric potential energy when under stress; the process by which electricity is generated is called piezoelectricity.

Insulation (including draft proofing and cavity wall insulation)

Multiples techniques of insulating will be used to achieve the best possible synergy in connection with the other systems used in the building. The main aim will be to insulate the building for thermal heat retention in order to reduce heat loss.  The way this will work is by reducing convection and radiation.

Bibliography

http://en.wikipedia.org/wiki/Building_insulation

http://en.wikipedia.org/wiki/Green_building

http://en.wikipedia.org/wiki/Photovoltaics

http://en.wikipedia.org/wiki/Green_wall

http://en.wikipedia.org/wiki/Green_roof

http://www.sustainabilityninja.com/sustainable-architecture/transparent-solar-photovoltaic-windows-by-rsi-solar-68691/

http://ugaecolivinglab.wordpress.com/2009/01/24/odum-green-building-concept-design-reveal/

http://www.copenhagenclimatecouncil.com/get-informed/solutions/one-step-at-a-time-power-generating-floors-at-tokyo-train-stations.html

Hazards & risk assessment 17.4

Task 1 – Write a full risk assessment for the reagent used in the analysis of inorganic chemicals. (Assignment 1.7) You are to identify the hazards, the symbols, and describe what safety precautions will be necessary. [M1][D1]

General rules which must be applied when working in any laboratory:

These rules will vary depending on the chemicals handled and in what way they are used.

Protective clothing

• varying from standard gloves, lab coats, goggles to full cryogenic clothing where extreme temperatures are involved and/or extremely corrosive or other chemicals are used.

Knowledge of the location of safety exits and hazard equipment in the laboratory, i.e. extinguishers and fire blankets.

Full attention to any task being performed

Following the rules indicated in the area one is present when handling chemicals.

  Flammable                 Harmful                  Oxidising                        

        

    Toxic                     Corrosive             Hazard to env.

        

Ammonia (corrosive; hazardous  to the env.; irritant; flammable)

Ammonia is a highly dangerous compound of nitrogen and hydrogen which needs to be handled very carefully to avoid any fatal accident. It is a highly corrosive chemical that will destroy any living tissue upon contact, and an irritant which means it may cause inflammation to living tissue, even in minute concentration; protective gear must be worn at all times when handling ammonia. This will also include in some cases the use of gas masks and specifically engineered ventilation present in facilities capable of handling ammonia in the form of vapour or gas, furthermore solutions greater than 25% in concentration develop pressure and will need to be ventilated. In gas state, ammonia is flammable under hot temperature and extremely toxic.

If in contact with ammonia water should be used to wash away as much of the chemical from any living tissue as possible and immediate medical attention should be obtained.

Hydrochloric acid  (toxic; corrosive; irritant)

Hydrochloric acid is a highly toxic chemical that will cause serious damage to health and must be handled very delicately. It has the potential to cause respiratory failure when inhaled and will destroy all living tissue in line with its corrosive attributes. In order to avoid any type of injury, the chemical will need to be kept in a well ventilated space as concentrated forms of this chemical will release hydrogen chloride vapour which is extremely harmful to health when inhaled. While handling the chemical, protective equipment will need to be worn; these will include safety glasses and chemical protective clothing. If the chemical should come in contact with any type of outer living tissue, water should be used to remove it. In case of respiratory failure or ingestion medical assistance should be sought after immediately.

Nitric acid soln. (oxidising; harmful; corrosive)

Nitric acid is powerful oxidising agent and must be kept separate from other types of materials; furthermore as a corrosive chemical it will destroy all living tissue and so care must be taken when handling. In order to reduce the risk of injury, this chemical will need to handled adequately by people wearing protective equipment which includes safety glasses and potentially gas masks should highly concentrated nitric acid be used. Additionally a well ventilated area is a must due to the harmful vapours released, particularly when heated. Should this chemical come into contact with any living tissue, water should be used to remove it. In all cases of serious contact and ingestion, medical assistance should be sought after immediately.

Sodium hydroxide soln. (harmful)

Sodium hydroxide solutions are harmful to living tissue, the strength of the solution being the deciding factor in the resulting damage. In all cases the eyes will be subject to the highest amount of risk, as even mild solutions will cause severe damage to the cornea. To avoid injury the chemical will need to be handled with protective gear, especially safety glasses with side protection to avoid any contact with eyes. In case of contact water should be used to remove as much of the chemical as possible, medical assistance will also need to be called immediately.

Silver nitrate soln. (oxidising; corrosive; dangerous to the env.)

Silver nitrate is harmful to living tissue, exposure on skin will cause stains which will not be removable with soap and water but will disappear once new skin grows. If exposure is considerable, side effects such as burns will become apparent. It is rarely fatal and side effects will largely depend on the concentration and time of exposure. However to avoid any complications, medical assistance should called immediately in any case of exposure to the eyes, skin or ingestion. Protective equipment and safety glasses must be worn to avoid exposure to skin and eyes.

Acids & alkalis 17.2

Task 2 – Explain the uses of the acids & alkali compounds identified in the experiment above. [M3][P3]

ACIDS

Sulphuric acid 

• Mainly used to produce phosphoric acid and to remove rust from iron or steel.

Hydrochloric acid       

• Used to remove rust from steel or iron, but also has some applications in the production of organic/inorganic compounds, and substance neutralisation.

Lemon juice 

• Used mainly in food production but can also be used to remove tarnish.

Vinegar           

• Used widely as a food additive, but also has some medical uses such as fighting infections. Due to its acidic property it can like many acids be used as a cleaning agent.

ALKALI

Hand soap      

• As the name suggests it is used as a cleaning agent for hands, it often has multiple substances (bactericidal and fragrances) and is harmless when in contact with skin.

Washing liquid

• Used to clean household products, notably cutlery and such because of its properties which remove oils and bacteria.

Bleach

• Strong household chemical with bactericidal properties, because of this is it most often used as disinfectant and steriliser. It is also used sometimes as a detergent.

Glass cleaner 

• Detergent which cleans glass as the name infers. Often contains a mixture of substance which removes dirt and oils.

Lime water     

• As various applications from producing precipitate of calcium carbonate to producing sugar.

Sodium hydroxide    

• Various applications, most commonly as a strong base in the chemical industry, most notably he paper industry. It is also used for in the production of sodium salts and detergents.

Ammonia

• One of the most widely used chemicals in the world, its applications are numerous. However it is mostly used as a fertilizer, with other application as a cleaner or fuel being relatively low in comparison.

Washing powder 

• Cleaning detergent containing water softeners, bleach and enzymes, used as cleaning agent for textiles.

Task 3 – Explain the meaning of acid, base and alkali. Include equations to explain what happens when they react.[D3] 

Acid

These are chemical compounds which have a pH reading less than 7, due to the hydrogen ions which form part of the compound. When dissolved in water acids release hydrogen ions, this is a universal property they all share because they all contain hydrogen ions. It is also why they all have similar properties.

Base

These are chemical substances which have a pH reading greater than 7, and are able to accept protons. When dissolved in water they release hydroxide ions which give rise to their similarity and same properties. When an acid and a base react together they form a salt and water, this property falls under a universal equation:

Acid + base –> salt + water

The product of this reaction is neither acidic or alkali which has given rise to the term neutralisation reaction.

As an example:

Hydrochloric acid + copper oxide –> copper chloride + water

Acid                                 Base                               Salt

2HCl         +      CuO        –>        CuCl2          +    H2O

Alkali

This is a soluble base; they are all bases and thus have all the properties that a base has. However bases are not always alkali. This has given rise to the phrase “All alkalis are bases, but not all bases are alkalis.” Alkalis are rather one set of bases, and there are many sets of bases.

Chemical analysis 17.1

Task 1 – Write a set of instructions for other team members explaining how the water and solid waste should be analysed. [P1] [P2]

A mining operation is believed to be discharging materials in a nearby stream, due to the materials they produced we believe that the stream contains both copper ions and bromide ions that are individually in the form of liquid compounds and are thus diluted in the stream. Analysis of the water will take place at multiple strategic points in order to identify whether or not they are discharging waste material in the stream.

Multiple samples taken at different locations will be taken back to the lab for analysis, and will be tested in the following method:

Samples will be categorised by location, and a second batch of samples will be put away until the first batch has been tested.

• Half of the samples of the first batch will be tested for copper ions by introducing sodium hydroxide. If the solution does indeed contain copper ions, a pale blue precipitate will be formed.
• The other half of the samples of the first batch will be tested for bromide ions by introducing silver nitrate. If the solution does indeed contain bromide ions, a cream coloured precipitate will be formed.

If no clear reaction can be noted in either test for copper or bromide ions the second batch of samples will be divided as in the same manner of the first batch. They will also be boiled in order to reduce the amount of water contained in each sample. Once this has been done they will be tested in the same manner as the first batch. If no clear result can be found for either test, we will conclude that the water does not contain either copper or bromide ions.

Furthermore we have reasons to believe that waste containing barium ions and carbonate ions as been dumped in a field. Samples taken from multiple suspicious waste piles will be collected and taken back to the lab for analysis and will be tested as follows:

• Half of the samples collected will be tested for barium ions by putting them a under a flame test. Outside impurities will be removed as best as possible by using a nichrome wire cleaned in dilute hydrochloric acid before testing.  If the sample contains barium ions then a green flame will be the result of the flame test.
• The other half of the samples will be tested for carbonate ions by diluting the sample into dilute hydrochloric acid or other available acid. Should they contain carbonate ions carbon dioxide gas will be emitted. Any type of volatile discharge due to effervescence will be collected and siphoned into limewater. If the limewater turns cloudy it will indicate that the waste contains carbonate ions.

Task2 – Explain how the formula of the compound in the stream and in the solid waste can be worked out. [M2]

If we know that the elements contained in the waste are copper ions + bromide ions, and barium ions +carbonate ions, we can add them together and balance them accordingly.

For example:

• Copper ions + bromine ions = Cu(2+) +Br(1-)

For every copper ion, 2 bromine ions will be needed to balance out their charges.

• Giving us the formula: CuBr₂

This equates to Copper bromide.

Similarly:

• Barium ions +carbonate ions = Ba(2+) + CO3(2-)

For every barium ion, 1 carbonate ion will be needed to balance out their charges.

• Giving us the formula: BaCO3

This equates to Barium carbonate.

Task 3 – A student has analysed some water from a river. He thinks that precipitation reactions show chloride ions in the water. He thinks that his flame test results show sodium ions in the water. Write a short comment on his work to explain why his conclusions might not be completely reliable and what he should do to improve the reliability and accuracy of his analysis.

Precipitates can sometimes be hard to identify accurately as they are similar in colour, as is the case for chloride and bromide.  Furthermore when extremely diluted, precipitations tests are not always reliable. In order to accurately identify in the ions in the water he has collected, the student should boil some of his sample in order to reduce the amount of water and increase the accuracy of his precipitation test. Once this has been done he should proceed with his precipitation test and to increase the accuracy make sure that precipitate is chloride and not another ion. In order to achieve this he will to introduce an ammonia solution to the precipitate and observe the reaction. If the ions are indeed chloride, then the precipitate will dissolve, if on the other hand it is not chloride then it will not.

Impurities can drastically affect the accuracy of flame tests. In order to increase accuracy and ergo the validity of his experiment, the student should use a nichrome wire that has been sterilised against all impurities by having been introduced to dilute hydrochloric acid and then put under intensive heat to get rid of any acid residue. Once this has been done the nichrome wire can be inserted into the sample and put over a flame. Any change in the flame colour will indicate what ion if any the sample he has taken contains.

New materials & nanochemistry 4.4

Task 1 – Name two productions which contain nanoparticles & two products that contain “new types of materials” [P4]

Polytetrafluoroethene or PTFE is a polymer which has been developed and perfected over many decades since the 1900s; it has extremely useful properties and can be found in many applications. It is water repellent, has an extremely low friction coefficient, high corrosion resistance, and chemical inertness (subject to creep).

Products 

• Armour piercing bullets coated in PTFE in order to reduce friction when fired, resulting in lower damage on the firearm’s rifling from the use of harder than average projectiles.
•  The Tefal range of products using PTFE as a component for their non-stick surfaces in cookware. PTFE’s properties of low friction make it an ideal choice for this type of application.

Titanium dioxide is an oxide of titanium which is harnessed mainly from naturally occurring minerals rutile, anatase and brookite.  It is widely used in the world for its commercial applications as a white pigment which can be used in food colouring (e.g. milk), opacity provider (e.g. paper, paint, ink, toothpaste) and also simply as a pigment for clothing. But it also has over properties including UV absorption and as a photocatalyst (sterilising, disinfection, oxidisation of organic matter).

Products

• Self-cleaning glass is coated with a thin film of titanium oxide which keeps its surface free of any dirt or residue through photocatalytic decomposition which would otherwise collect over time on regular glass.
• Water which has been disinfected by adding titanium oxide (as well as nitrogen to make it absorb visible light, and nanoparticles of palladium to the surface of the TiO₂ fibres). The result is a disinfectant which uses visible light rather than UV light, and continues to work even after the light is gone.

New types of materials

• Self healing metal, this is metal which has been coated with fluid filled capsules that have the potential to, among other things, repair the surface of the metal when they burst, as would be the case during an impact.
• Glass which has been infused with metals in order to increase its strength and toughness; this could have many applications in fields which require high strength/tough materials. According to the researchers this new type of glass is stronger than steel or any other known material.

Task 2 – Give the main ingredients for the products mentioned in Task 1. For example you are to explain the nanoparticles involved, in addition to other substances and the reason for adding these products in the “new materials”. [M4]

Polytetrafluoroethene is composed of fluorocarbon solids; these are themselves composed of carbon and fluorine bonded together to form extremely strong carbon-fluorine bonds.

Armour piercing bullets

• They are simply coated with PTFE to reduce barrel wear; this is needed because armour piercing bullets are much harder than regular bullets and are more prone to damaging firearm rifling (helical grooves in the barrel of a gun that impart the projectile to spin in order to stabilize it). PTFE in this instance is used because of its low friction quality.

Tefal non-stick equipment

• This is cookware that has been coated with PTFE to reduce friction and repel water, resulting in cookware which does not stick to food while cooking making it much easier to cook and clean with. PTFE in this instance is used for its hydrophobic and low friction qualities.

Titanium oxide (TiO₂) is an oxide of titanium and as such is composed of titanium and an anion of oxygen.

Self cleaning glass

• The glass that has been coated with a thin layer of titanium oxide, this layer helps the glass to stain clean, it is self cleaning in the sense that if water is provided, a process will occur which removes the dirt and grime from the window.  TiO₂ Reacts with the UV light to break down organic material and reduce the adherence of non biological material (inorganic material i.e. minerals), this stage of the self cleaning process is referred to as “photocatalytic”. Second is the Hydrophilic stage, the coating has been activated by the UV light during the photocatalytic stage and has been rendered hydrophilic (was hydrophobic) and can now attract the broken down organic material and inorganic material and as it spreads the water evenly over its surface, washes away both organic and inorganic material from the glass.

Disinfected water

• The water is disinfected using mostly fibres of TiO₂, nitrogen is then added to allow for the absorption of visible light. This nitrogen and TiO2 mix can kill bacteria but not efficiently. To remedy this nanoparticles of palladium are woven into the surface of the TiO₂ fibres, thus greatly increasing the efficiency of the disinfection by increasing the photocatalyst’s power (TiO₂). The positively charges holes, created by the photons as they hit the material on the surface of the nitrogen infusedTiO₂ react with water to produce hydroxyl radicals which attack bacteria. This is where palladium is invaluable to create promising results; the nanoparticles grab the electrons and stop them from neutralising holes, thus achieving a somewhat constant rate of disinfection. When the light is switched off the nanoparticles slowly release negative charges that they have been storing, resulting in continued reaction with the water which produces oxidising agent so the disinfectant can keep working without light. Tests performed showed that only a small amount of light was needed (minutes) for the disinfectant to kill bacteria for up to 24 hours.

Self healing metal

• The main draw here is the coating containing the mini capsules, this coating for the moment has only been tested with polymers that can repair metals when burst open. They could however, theoretically, be filled with anything and thus adapted to much more applications than just metal coating, such as minerals oils. Using minerals oils, they could be very useful in keeping ball bearings self-lubricated. The coatings are made from metals or alloys including copper, nickel and zinc because can be electroplated and used in more applications. However this technology is still in its infancy and public demonstration have not yet been made.

Strong glass

• Infused with different kinds of metals, this glass can withstand huge amount of force while also having the capacity to resist fracturing, unlike other types of similar technology. Using glass made of palladium and four other elements, palladium does in this case what other elements have failed to do so far in this application, to increase plasticity and prevent the glass from breaking. It does this by creating much more “shear bands” which are small defects which would eventually form cracks, but with palladium they are so many they block each other and stop any cracks from forming and propagating throughout the material without impairing any of the original properties. Three other elements are already contained in the glass from the start; these are phosphorous, silicon and germanium. The fifth however is not, this is silver, it is added to increase the bulk of the material without causing it to become brittle, as such only a small amount is added.

Task 3 – Explain some of the concerns linked with using nanoparticles. [D4]

Surely, the most pressing concern that the world is faced with today regarding the use of nanoparticles is the effects they have on health. There have been studies that report nanoparticles may cause cancer and other health problems, but of course the particular problem is dependent on the type of particle which include, size, shape, chemical composition and specific properties. All of which need to be assessed independently to report accurate findings, that can be reliable and depended on for their accuracy.

What makes nanoparticles so potentially dangerous is their size, undetectable to the naked eye, they are small enough to enter the human body and cause serious damage by flowing in the blood or entering vital organs without one noticing. For example a nanoparticle that can easily dissolve and is chemically dangerous to the body may cause a lot of damage to an organ, especially as the concentration of the particle increases. It has been found in soem studies that nanoparticles can be even more dangerous than large particles because of their ability to get into places their large counterparts cannot.

While other types which do not dissolve but accumulate such as titanium dioxide which can be found in sunscreen, have been at the centre of debates on whether they really are carcinogenic, with most studies reporting that it is not a carcinogen but can cause, at least in rats, slight lung fibrosis. But with little information on long term use in humans, this data is in no way completely reliable but does paint a plausible picture into how dangerous TiO₂ is.

Directly related, is the changes in the characteristics of particles that have been observed due to the very nature of the change in size, largely due to the increased surface to volume ratio resulting in more molecules of a chemical on the surface, at least much more so than would be found on larger molecules. This is pointing towards a reason why nanoparticles are much more toxic, because of their increased surface.

Of great importance is also the effect that production of nanoparticles has on the environment, long term studies that can evaluate the potential damage of nanoparticle exposure and effects on a wide range of species has not been done and so very little information is available.

In conclusion, there are major health concerns with using nanoparticles, most of which however are not defined enough for informed decisions to be made about whether or not they should be used or more reasonably under what conditions. Progress should be made if just for the sake of advancement in technology but not at a cost so high that it becomes irreversible, regulations need to be implemented all new designs thoroughly tested before implementation in commercial or industrial sectors and that is exactly what many organizations would like to see. For example the Royal Society is clearly aware of the potential for nanoparticles to penetrate the skin and has recommended for the use of nanoparticles to be evaluated by the European Commission before being accepted for commercial use. It would seem however that the process of evaluating the potential dangers and counteracting them to have available technology available to use as soon as possible is being done too slowly.

Bibliography

BTEC level 2 Applied Science Edexcel 2010

http://ec.europa.eu/health/opinions2/en/nanotechnologies/l-3/6-health-effects-nanoparticles.htm#2p0

http://www.techreview.com/biomedicine/24415/page1

http://www.technologyreview.com/computing/27046/page1

http://www.technologyreview.com/computing/23138/page1

http://en.wikipedia.org/wiki [Nanotoxicology,palladium,hydrophile, self-cleaning glass, photocatalysis, Teflo, fluorocarbon]

Organic compounds & molecules 4.3

Task 2 – Describe the uses of Alkanes, Alkenes, Alcohols and Carboxylic acid in society. [M3]

Alkenes have not been used as long as other types of perhaps more crude organic compounds, however in today’s society they are used more than ever. When heated up at high pressure with a catalyst they form a polymer under a process called polymerisation. The type of polymer formed will depend on the alkenes used or as they are called when involved, monomers.  Polymers are widely used as construction materials, packaging and even bullets among others. They are relatively cheap to produce, very durable and can take on many different properties which are extremely under certain conditions, such as hydrophobicity or malleability.

Alcohols have been used for millennia’s, however only recently have they been used for so many applications including, sterilisation, recreational use, food additive (aromatic), fuel, as a solvent and many more. In recent years its viable ability to be used as a fuel as been highlighted by the media, mainly because it is a renewable substances as it can be produced from plants using basic fermentation techniques and then refined using other methods.  Its properties as a fuel however have only been talked about in recent years, but as an additive to gasoline it has been used far longer. As a solvent, alcohol is used extensively in the cleaning and cosmetic industry because it is able to dry very quickly, sterilizes and dissolves many substances.

Alkanes are saturated hydrocarbon and as such have only a single bond between carbon atoms, this property makes them unreactive with most other elements apart from oxygen (combustion).  They are mostly found in the form of natural gas or crude oil and for this are known particularly well for being fuels. However they are also found in many other places but in much smaller quantities, such as animals which produce them to create certain fragrances which attract the opposite sex, a process which is useful for mating. The type of application an alkane will be used for and how it will be stored depends on the number of carbon atoms it is composed of. Currently low carbon count alkanes are used in heating, while higher types are used as additives to fuel.

Carboxylic acids are currently used in vast quantities in the food industry, specifically in the role of food preservatives due to its acidic properties that many types of bacteria are unable to survive in. They are also used in another branch of the food industry, this time in a slightly modified form, esters. Esters can be formed by reacting carboxylic acids with alcohol and concentrated sulphuric acid, the smell and taste will be sweet and usually resemble a type of fruit. They are however used in many other types of applications such as polymer, solvent or pharmaceuticals production.

All the types of organic molecules described above are used in abundance in society, from the food we eat to the fuel we use; they are present in every facet of our lives. Their properties and possibility for modification and reaction with other elements are so vast that they are used similar fields to achieve different effects; it is this diversification which makes organic compounds so valuable in our age.

Task 3 – Explain the benefits & disadvantages of organic compounds in society. [D3]

Organic compounds in the past have been found in abundance; they were harvestable and produced a cheap and more powerful way to fuel new technologies in comparison to wood. In today’s society their role as a fuel as not changed, however their supply is spiralling down and their use has been increased massively to cope with not only fuel demands, but the production of new materials built using organic compounds and their different properties as base material.

The use of organic compounds as fast forwarded our technological advances in the past few hundred years, and revolutionised our society to the point where we can now realistically switch to alternative energy sources and building materials. In this regard, organic compounds have been heralded as the driving force of our times. There is no doubt of the various benefits that organic compounds have brought:

• Fuels in the form of kerosene, petrol, and coal among others
• Base material for the production of polymers
• Alcohol as sterilisers and solvents
• Food preservation

Unfortunately the use of organic compounds is extremely damaging to the environment in the long term and can potentially have damaging effects on humans in the form of cancer. This negative effect has dominated the media these past few decades. However, a growing concern that our planet is unable to cope with the amount of harmful waste released when using organic compounds, has been a major force in the development of alternative energy sources.

Changing to these alternatives has been slow nonetheless due to the massive alteration needed on existing infrastructure to accommodate these new types of technology. An immediate change would cost trillions and have a crippling effect on the industries which are solely based on using or relying on the continued use of organic compounds. For this reason gradual change has been seen as the most suitable way to adapt. The cost would be relatively similar but allow for industries to adapt and plan in order to have a place in the new world.  It would also allow for people to change their lifestyle gradually as their finances and needs change, saving them a massive upfront cost.

The most basic example is of course our use of oil as fuel; billions of people rely on their vehicle as a mode of transport. Scrapping of all these vehicles for new ones using alternative energy sources is unviable, even more so when doubt of the effects of carbon dioxide emissions on the planet is widespread. Furthermore millions of individuals working in this industry could find themselves made redundant, a highly unfavourable approach for many citizens and as such unfavourable for any party to promote.

In conclusion, although the many benefits of organic compounds are still present and their use has made the society we currently live in possible, it is undoubtedly becoming redundant in energy conversion ratios, surely redundant in the effect on the environment, and ultimately ourselves. Whether organic compounds are here to stay or not is a decision which will take many decades to be made globally, in the meantime the current approach of many leading nations and our own is to opt for gradual change and push alternatives as far as finances and current populace opinion allows.

Bibliography:

BTEC level 2 Applied Science Edexcel 2010

Chemical bonding & properties of substances 4.1

Task 1 – You are to carry out an experiment on three unknown substances to determine their type of bonding. (see sheet AS1) Using the evidence, decide what type of bonding is found in the unknown substances. [P1]

Aim

• Investigate the typical properties of solids with ionic, covalent or metallic bonding.

Method 

• Five solids were examined to determine whether they were dull/shiny, smooth/crystalline or brittle/malleable.
• An electrical circuit composed of a battery and light bulb was set up in series, and each solid was placed on different watch glass. Two crocodile clips attached on the connectors were held against the solids (apart from each other) to determine whether they were electrical conductors, if indeed that was the case the bulb would light up.
• Using a tripod, Bunsen burner and tin lid; each solid was placed on the tin, one at time a time, and left for a few minutes or until a change in the solid was observed due to the heat generated from the Bunsen burner.
• Each solid was placed in a test tube half filled with water and gently shaken to determine whether they would dissolve.

Results 

	Physical state	Conductible	Effect of heat	Soluble (water)	Bonding
Copper powder	Shiny, smooth, malleable	No/yes (variables)	Hardens and blackens	No	Metallic
Paraffin wax	Dull, smooth, brittle	No	Melts	No	Covalent
Sodium chloride	Shiny, crystalline, brittle	No	Fizzes	Yes	Ionic
Copper	Shiny, smooth, malleable	Yes	Becomes more malleable	No	Metallic

Conclusion 

Each experiment carried out on the solids revealed their bonding through their properties; physical state at room temperature and when under heat, solubility in water, and conductibility. All of these were tested out and the result can be observed above. Using known evidence, the properties were used to identify which bonding the solids belonged to.

As such it can be observed that solids which were conductible, did not melt (less than 1000C Celsius), or dissolve in water were metals and thus had a metallic bonding. Solids which were not conductible, did not melt, but dissolved in water were found to have an ionic bonding. Solids which were not conductible, melted but did not dissolve in water were found to have a covalent bonding. All of these properties are in line with known evidence and so the findings of the experiment prove the characteristics to be true.

Task 2 – You are working for a decontamination company which has been called in to advise on the best way of disposing of chemicals at an abandoned chemical plant. The chemicals are in the unlabelled containers. The chemicals are:

• Sodium chloride, an ionic compound which can be disposed of safely into the sea nearby.
• Paraffin wax, a covalent compound which can be buried in a landfill.
• Zinc metal, which must be recycled.

Work in a group of 3 to devise some tests which you could do to be certain which chemical is which.

Present your findings as a powerpoint presentation. To convince your audience that you are right, you should also try and explain how the bonding helps you to explain the property. [M1][D1]

In order to identify which chemical is which, multiple tests can be performed that would clarify their type of bonding and thus the best way to dispose of them.

All three chemicals should first be tested for conductibility when solid, the reason being that only metallic substances are conductible in their pure state, with covalent substances being non conductible and ionic substances only when dissolved in water.

Secondly, solubility in water should be tested; ionic substances are soluble whereas most covalent substances are not. The chemicals are described in task 2 which leads me to assume that the decontamination company knows the presence of the three chemicals just not, which is which. Therefore they would know after the solubility test that one of the chemicals is soluble and the other is not, by deduction, the one that is not must be the paraffin wax.

All three chemicals could be tested further for increased assurance of conclusions, but I would find it unnecessary* as all properties found in the two test exclude one chemical each time as these properties are unique** to the type of bonding.

Expressing properties of substances based on their bonding is relatively similar to expressing the vice versa. For instance, in metallic bonding, negatively charged electrons are free to move around positive ions, it is this unique property in (most) metals which allows it to conduct electricity even when solid. Knowing that metallic bonds are arranged in such a way as to allow the free roaming of electrons, one can assume that this will suggest specific properties inherent to most substances with metallic bonding such as conductivity, malleability and hardness.

In conclusion, if one understands the properties of a substance, one can identify what type of bonding is present and as such what type of substance it is. Vice versa, if one understands the bonding of a substance, one can identify its properties as they are inherent to the vast majority of that substance.

*(should all the tests afore mentioned have been executed without any variables)

**Unique, if we consider that the chemicals are known, thus eliminating the exceptions of covalent substances which are soluble in water.

Additional physical properties & industrial chemistry 1.5

Task 1 – Carry out the practical looking at chemical reactions which are exothermic and endothermic on the attached sheet A. [P2]

Aim

• The aim of the experiment was to observe energy changes caused by a chemical reaction.

Hypothesis

• Energy is either given out and or taken in when a reaction occurs, through this experiment, finding out whether it was increasing or decreasing, exothermic or endothermic was the aim.

Method

• Eight different substances had their temperature measured prior to being mixed with each other.
• Substances are mixed with each other as outlined in the table below.
• Their temperature was checked and compared with the unmixed temperatures to define whether they were exothermic or endothermic reactions.

Reaction	Temperature before mixing/C	Temperature after mixing/C	Exothermic or endothermic
Sodium hydroxide solution + dilute hydrochloric acid	20C	22C	Exothermic
Sodium hydrogen carbonate + citric acid	19.5C	19C	Endothermic
Copper(II) sulphate solution + magnesium powder	20C	57C	Exothermic
Dilute sulphuric acid + magnesium ribbon	20C	45C	Exothermic

 

Conclusion

• A change was observed in each reaction, and all were exothermic save Sodium hydrogen carbonate and citric acid. The reaction gave conflicting results, however it was deduced that the reaction was endothermic. Depending on the solutions used the reaction and the speed at which the temperature increased were somewhat different, ranging from slow to more or less violent reactions in comparison.

Task 2 – Describe the term “exothermic “and “endothermic”, reaction. Explain the temperature change that has occurred from task 1. [M2]

An exothermic reaction is one which releases energy in the form of heat, thus as the reaction occurs the temperature can be observed to increase. The reason being that the energy needed to break the bonds of the reactants is lower than the energy needed to create the bonds of the products; as such the extra energy is released as heat.

While an endothermic reaction is one which absorbs energy in the form of heat from the surrounding meaning that it requires a certain amount of thermal energy, thus when an endothermic reaction takes place the temperature decreases. The reason being that the energy needed to break the bonds is higher than the energy released when forming the product; as such energy is taken in, thus the temperature of the product is lower than the reactants.

In task 1 the solution used to form new products were exothermic or endothermic depending on their energy output, from what was observed most of them were exothermic. As explained above, whether they were exothermic or endothermic was decided by the energy needed to break the bonds and the how much of that energy was needed to create new bonds.

Task 3 – Calculate and explain the energy changes ΔH for the following reactions. [D3]

CH₄ has 4 bonds of C-H                                                  413×4 = 1652

2O₂ has a O=O bond and 2 molecules                      497×2 = 994

= 2646

Co₂ has 2 C=O bonds                                                      740×2 = 1480

2H₂O has 2 bonds of O-H and 2 molecules             463×4 = 1852

= 3332

2646-3332 = -686

                                                                       ______________________________

C₃H₈ has 10 bonds C-C-C and 8 H bonds                  436×2 = 872

413×8 = 3304

5O₂ has a O=O bond and 5 molecules                      497×5 = 2485

= 6661

3CO₂ has a C=O bond and 3 molecules                    740×6 = 4440

4H₂O has 2 O-H bonds and 4 molecules                  463×8 =3704

= 8144

6661 – 8144 = -1483

The energy needed to break the bonds is lower than the output energy needed to form the new product bonds, as such the reaction is exothermic in both reactions, has proved by the negative ΔH when subtracting the product from the reactants.