You are here: UK Essays » Essays » Sciences » Chemical Fertilisers

Cookie Information

Privacy Information

Chemical Fertilisers

Science Research Assignment

Table of Contents

TOPIC 1: CHEMICAL FERTILISERS: ARE THEY FEEDING THE NATION OR DIMINISHING OUR NATURAL RESOURCES? 3

Nutrients and Fertilizers 3

Processes involved in the production of chemical fertilisers 5

The Haber Process 5

The Oswald Process 6

The Contact Process 8

Eutrophication 9

Natural vs. artificial fertilisers 10

Concluding Essay 12

TOPIC 2: IS THE GAIN IN THE ECONOMIC WEALTH- FOR THE SOUTH AFRICAN CHOR-ALKI INDUSTRIES- WORTH OUR HEALTH? 14

The industrial production of chlorine, sodium hydroxide and hydrogen 14

The products of this process 16

Laboratory simulation 19

Concluding Essay 21

Bibliography 23

TOPIC 1: CHEMICAL FERTILISERS: ARE THEY FEEDING THE NATION OR DIMINISHING OUR NATURAL RESOURCES?
Nutrients and Fertilizers

Give a brief explanation as to the function of nitrogen, phosphorus and potassium in plants.

Nitrogen, phosphorus and potassium are all primary macronutrients which come from the soil and are dissolved in water to be absorbed by the roots of the plant. Nitrogen is part of a plant’s chlorophyll which helps it undergo photosynthesis. It improves plants growth, seed and fruit production and the quality of its leaves as well as forming an essential part of the proteins, enzymes and metabolic processes concerning transfer of energy. Phosphorus also contributes to the photosynthesis process by converting solar energy into chemical energy which can be used by the plant. It also encourages growth, blooming, root development and forms the oils, sugars and starches that a plant produces. Lastly potassium builds protein, helps in photosynthesis, improves the quality of the fruit and reduces disease.

(Troxler)

Give and explanation as to how plants and animals absorb nitrogen, phosphorus and potassium.

Plants are autotrophic so these mineral nutrients dissolve in water and are easily absorbed by the root of the plants as ions (nitrogen as NH4+ or NO-, phosphorus as H2PO4- or HPO42- and potassium as K+) as long as the soil has a relatively neutral ph. The animals, which are heterotrophic, absorb theses nutrients through consuming the plants.

(Morgan), (Enviro Briefs)

Where did farmers get their sources of N, K and P before the First World War? Give a brief description of each.

Before WWI nitrogen was sourced for use in fertilisers in the forms of saltpeter and guano. Chile saltpeter accounted for 60% of the world’s supply in the 19th century. Saltpeter generally refers to the potassium nitrate which is the precipitate formed when sodium nitrate, mined in Chile, is treated with potassium chloride. Guano refers to excrements that don’t break down as fast as other organic matter as they are found deep within caves where they are protected from wind and sunlight. Guano is not only rich in nitrogen but phosphorus too, which makes it ideal for fertilizers. Phosphorus was also sourced through phosphate rocks and by treating ground bones with sulphuric acid. And finally potassium is found in the form of potash which is more commonly known as potassium carbonate which is the residue remaining once wood ash is leached and the solution is evaporated.

(Zmaczynski), (Foster), (Mithra), (Sauchelli, 1949), (Potash)

Give a short overview as to the history of fertilisers in South Africa.

Although organic fertilizers had been used as far back as 1608 when Jan van Riebeeck recognised the fertility of the soil in the Cape, the first local manufacturing of chemical fertilizers began in 1908 when a phosphate plant was commissioned by the South Africa Fertilizer Company using animal bones found in Durban. In the 20th century, as the mining industry took off, the need arose for the production of explosives and as a result in 1919 Kynoch and in 1921 Cape Explosives were established. A by-product of this industry is sulphuric acid which is used in the production of chemical fertilizers and along with imported rock phosphates lead to the development of Kynoch in Umbogintwini and Capex at Somerset West which later became AE&CI in 1924. They were joined by Omnia and Triomf soon. While local and imported products were originally mixed, the industry was boosted when imported products diminished during WW2. Price control was introduced as a post war measure which left South Africa’s protected industry to thrive in the 1950s and development of SASOL, ISCOR and FOSKOR to take place. Liberation of trade policies, the most severe drought in two centuries and global recession lead to the restructuring of the fertilizer industry causing Sasol to start trading directly to farmers and Triomf and AECI’s union to dissolve. Since then Foskor has obtained IOF and today and South Africa’s fertilizer industry has continued to develop and still distributes not only locally but internationally. Excluding oil the fertilizer industry in South Africa forms 20% of our chemical industry.

(Ratlabala, 2003), (G.J. van der Linde, 2006)

Explain the meaning of the N: P: K ratio on fertiliser bags. Give a few examples to explain this.

The N: P: K ratio on fertilizer bags tells you the percentage of nitrogen, phosphorus and potassium in the fertilizer. If there is no number in brackets after the ratio, the three numbers represent percentages, where as if there is a number in brackets following the numbers the first three numbers are ratios while the number if brackets is the percentage of pure fertilizer. In the latter case to work out for instance the percentage component of nitrogen you must take the value of nitrogen, divide it by the sum of the first three numbers and multiply it by the number in brackets. The ratio you use is dependent on the type of plant you wish to grow in the fertilizer and features you wish to enhance. Examples of ratios include:

(Pillay)
Processes involved in the production of chemical fertilisers

The Haber Process

6.1. Write a Chemical equation representing the Haber Process.

N2(g) +3H2(g) [image] 2NH3(g) ∆H = -92kJmol-1

(Clark, 2002)

6.2. How are the nitrogen and hydrogen, used in the process, produced?

For the Haber process, both nitrogen and hydrogen are needed as reactants. Air is made up of 78% nitrogen and 21% oxygen. To get nitrogen alone the air is first filtered to remove dust particles. It is then liquefied by freezing it to -200°C during which the water vapour condenses and is removed using absorbent filters while the carbon dioxide freezes at -79°C and is removed. This leaves you with liquid nitrogen and oxygen that is separated using the process of fractional distillation due to their different boiling points. A hydrocarbon (e.g. methane) undergoes steam reforming when added to water and forms carbon monoxide and the hydrogen which is used in the Haber Process.

(Clark, 2002), (Pillay)

6.3. Explain, by referring to reaction rate and chemical equilibrium, the condition under which the Haber Process is carried out.

When carrying out the Haber Process the conditions need to be considered in terms of the catalyst, temperature and pressure in accordance with their effect on the rate of reaction and chemical equilibrium. In each case the desired effect is that the equilibrium is pushed furthest to the right to ensure maximum ammonia production. The forward reaction is exothermic and Le Chatelier's Principle says that by lowering the temperature the equilibrium will shift to the right which is favourable. But 400-450°C is used which is not considered as a low temperature, this is because the lower the temperature the slower the reaction takes and longer it will take to produce the ammonia; so when the industry is considered these temperatures have been found ideal as they achieve a reasonably high proportion of ammonia in a short time. Le Chatelier's Principle also says that when the pressure of the system is increased the side producing the least molecules will be favoured. In the equation we can see that there are four molecules on the left and two on the right which means that by increasing the pressure the equilibrium will be pushed to the right favourably in terms of production of ammonia. In terms of rate of reaction a high pressure also causes the molecules to be compact and increase the chances of hitting the catalyst and reacting. Therefore 350 atmospheres is ideal in terms of production, yet the expense of maintaining this high pressure and the infrastructure (piping) needed is excessive so often 200 atmospheres is the compromise where the cost of producing the ammonia does not exceed the price it can be sold for. While the catalyst does not affect the position of the equilibrium the addition of the catalyst ensures that the reaction reaches dynamic equilibrium for the short amount of time it is in the reactor.

(Clark, 2002), (Lucas, 2008)

6.4. What is the significance of this process in the fertilizer industry?

Plants require soluble nitrogen compounds so that the nitrogen can dissolve in water and be absorbed by the plants routes. Plants cannot convert atmospheric nitrogen into this soluble nitrogen and therefore fertilizers are used to supply this nitrogen and improve the plants growth. The Haber Process converts atmospheric nitrogen into ammonia which can be absorbed by the plant roots. Not only has this changed the way nitrogen fertilisers are produced but has made them more available and even become part of what has been labelled the “Green Revolution” of the 20th century as the production of ammonia in this way is environmentally friendly and doesn’t deplete our resources.

(Zmaczynski)

The Oswald Process

7.1. Draw a flow chart to represent the various stages of the Oswald Process. Your flow chart must show the chemical equation for the reaction which takes place at each stage. [image](Manufacturing Nitrates: the Ostwald process)

7.2. Explain, by referring to the reaction rate and equilibrium, the conditions under which the Oswald Process is carried out.

Conditions leading to a 96% yield rate are that the temperature is between 975 and 1125 K, the pressure is at 4 - 10 atmospheres (400-1010 kPa) and a platinum-rhodium catalyst is used. Although the initial reaction is exothermic as we can see from the heat of reaction being -950kJ and so to shift the equilibrium to the right would require a very low temperature; a high temperature is used to ensure a fast rate of reaction as if a lower temperature was used it would take very long to produce the product and for the reactants to convert to product. The pressure sustained is lower than that of atmospheric pressure in order to shift the equilibrium to the right. The forward reaction produces more molecules than the amount of molecules that form the reactants. Therefore by lowering the pressure the forward reaction is favored. A catalyst is also used to lower the activation energy of the molecules allowing for more effective collisions and a faster reaction rate.

(Ostwald Process)

7.3. What is the significance of this process in the fertilizer industry?

Through the Oswald Process, ammonia is converted to nitric acid and is used to produce nitrogen fertilizer. This is done in a process known as nitrophosphate which creates a mixture of phosphoric acid and calcium nitrate by acidifying phosphate rocks with the nitric acid. Once cooled, calcium nitrate crystals can be separated from the phosphoric acid which creates the nitrogen fertilizer. This fertilizer is ideal as it is very soluble and can therefore be easily absorbed by plants.

(Nitric Acid), (Pillay)

The Contact Process

8.1. Draw a flow chart to represent the various stages of the Contact Process. Your flow chart must show the chemical equation for the reaction which takes place at each stage.

(Pillay)

8.2. Explain, by referring to reaction rate and equilibrium, the conditions under which the Contact Process is carried out.

In equilibrium, in order to yield the largest amount of product the equilibrium must be pushed to the right to favour the forward reaction. The contact process is carried out at 400-450°C and 1-2 atmospheres which both are a compromise. While Le Chatelier's Principle states that the right side will be favoured if you lower the temperate since the reactions is exothermic, if you do lower the temperate the rate of reaction will also decrease and although increasing the pressure increases the rate of reaction and the favour the side with fewer molecules is (which in this case is the right side); it is too expensive to maintain high pressures or pipe the infrastructure so the pressure is lower and more feasible.

(chemguide)

8.3. What is the significance of this process in the fertilizer industry?

The contact process is used to prepare sulphuric acid. As previously mentioned phosphorus is a macronutrient and therefore is an essential component in fertilizers as it promotes flowering and seed production. We know they need to come in the form of phosphates so that they can dissolve in water and be absorbed by roots and in this way are most commonly supplied in the form of superphosphate or triple superphosphate. To achieve superphosphate phosphate, rock is mined and treated with sulphuric acid, the product of the contact process , therefore this process is significant to the fertilizer industry in that it is the product that allows for the production of phosphates for fertilisers ensuring optimum plant development.

(The Fertilizer Industry)

Eutrophication

9. Describe, in detail, the term ‘eutrophication’, with specific mention to its causes and its consequences.[image]

Eutrophication is the process during which water bodies (eg. Lakes, estuaries, slow moving streams) receive an excess of nutrients (nitrogen and phosphorus) which stimulate plant growth and lead to the degrading of water and habitat quality. These nutrients come from the run off of fertiliser from farm lands, suburban lawns and sewage treatment plants. This promotes the growth of algae which affects the ecosystem in that it can and does support higher yields of fish, but it also fuels bacterial growth which results in the water becoming hypoxic which is fatal for marine life and result in a decrease in biodiversity.

(Cloern, 2007), (Toxic Substances Hydrology Program )

10. How does the fertiliser industry contribute to eutrophication?

Fertilizers are largely made up of nitrates and phosphates. The nitrates are highly soluble in water and so easily reach rivers as part of run off or percolate into the groundwater. Phosphates on the other hand are not soluble in water but move with the soil which tends to eventually erode into the ocean. So through the inclusion of these nutrients in fertilizers contributions to eutrophication are being made as these nutrients inevitably find their way to a body of water. Eutrophication is a natural process happening at en elevated rate due to the excess reception of these nutrients which is evident from the higher levels of eutrophication in agricultural areas where these fertilizers are being used.

(Oregon State University, 2008)

11. Suggest ways to prevent eutrophication.

Eutrophication can be prevented through minimizing nonpoint pollution by having Riparian buffer zones near waterways to filter pollutants and stop the nutrients before they travel too far or get too close to bodies of water, laws such as the ones regulating sewage treatment must be made to manage the use of fertilizers and imposition of animal waste, and by testing fertilizers to create a model that optimizes use and does not have excess nutrients in it which is also cost effective. Other solutions also include reducing livestock density, treating urban runoff streets and drains ,and reducing nitrogen emissions from cars and plants.

(Cloern, 2007), (Eutrophication, 2006)

12. Suggest ways to solve the problems that arise from eutrophication.

Although ways to prevent eutrophication have been discussed the remediation of eutrophic water bodies is also of importance and can be dealt with through dentrification, bacterial augmentation, phytoremediation and dredging. Dentrification removes nitrates from the water by converting them to the natural gas nitrogen which is released into the atmosphere. The nitrates encouraged the growth of algae which removes oxygen from the water. Through this the algae bloom will slow and the survival of other species will improve. Bacterial augmentation can be used to remove organic sediments and control the rapid growth of aquatic weeds. Phytoremediation uses plants in soil and static water to absorb and break down pollutants and finally dredging which is an expensive process that gathers up sediments from the floor of the water body that often have high levels of phosphorus and relocating them.

(Cordaro), (Dredging), (Carl Etnier), (Phytoremediation)

Natural vs. artificial fertilisers

Draw up a list of the advantages and disadvantages of:

13.1. Natural fertilisers such as manure and compost

• Improves soil structure and absorption of water.
• Contain a range of nutrients.
• Makes use of waste products.

• Costly to transport.
• Storage is difficult.
• The soil deteriorates with time and is in bulk.
• Insufficient amounts of the raw materials needed to make it.

(Pillay)

13.2. Chemical fertilisers

Advantages

• production of the fertilizer is faster.
• Contains all there essential nutrients.
• Can be suited to the product that will be farmed.
• Readily available.
• Easy to apply.

Disadvantages

• Results in acidic soil.
• Has no energy which a plant must attain from its organic surroundings or carbon which is an essential element in the plants growth.
• Pollute water.
• Releases the greenhouse gas nitrous oxide and degrades the ecosystem.
• Water soluble.

(The advantages and disadvantages of chemical fertilizers), (A Comparison Of Organic vs)

13.3. Organic farming

Advantages

• Produce has a higher mineral content and is not contaminated with chemicals such as pesticides, fungicides and herbicides that can result in disease
• Produce keeps longer.
• Saves cost on agrichemicals.
• Crops are healthier and therefore more resistant to weeds.
• Plants are more tolerant to droughts.
• Nutrients bind and do not leach out of the soil making it long lasting.

Disadvantages

• Productivity lessens as soil ages and loses its ability to convert organic matter into fertility.
• Land needs to be continuously cultivated.
• Genetically modified and engineered crops that are designed to resist pests aren’t used.
• More labour intensive and skill required.
• Slow to release nutrients.

(Advantages and Disadvantages Organic Farming: Good Things, Barriers and Environmental Effects), (A Comparison Of Organic vs)

Concluding Essay

To answer whether chemical fertilizers are feeding the nation or diminishing our natural resources we need to look why and to what extent they are used, the negative affects they are having on our environment and if there is a viable more eco-friendly solution.

Plants take up nutrients through their roots and return them to the ground once they die and begin to decompose. This forms part of the natural cycle which is disturbed by harvesting crops which leaves the soil lacking in nutrients. Chemical fertilizers replace the essential elements namely nitrogen, phosphorous and potassium. They are necessary for plant growth, making proteins which are the food source of many animals, developing green leaves and strong stems, allowing larger yields and fields being able to be harvested year after year. These chemical fertilizers already feed up to 2 billion people and with population growth comes an increase in food demand which leaves low soil fertility from intensive cultivation, inadequate replacement of nutrients, deforestation and erosion our biggest threats and the use of chemical fertilizers seemingly our only option and lifeline.

[image]While chemical fertilizers would seem to be the solution, their use is also having devastating effects. Over-use of fertilizer affects both the terrestrial and aquatic ecosystems. Nitrogen saturation can actually lead to a decrease in the soils fertility; it disturbs the chemistry of the soil, leading to the loss of nutrients such a s calcium, magnesium and potassium as well as allowing nitrogen-responsive species to dominate leading to the disappearance of other species and in turn lowering biodiversity. Run-off from crop lands lead to eutrophication (water bodies with receiving excess nutrients) which encourages algae blooms that strip the water of the oxygen that is essential to its aquatic life, creating dead zones and increasing the turbidity of the water. The use of fertilizers that are produced with nitric acid or ammonium bicarbonate also contribute to the climate change resulting from global warming through their emission of greenhouse gases such as nitrogen oxides, nitrous oxides, ammonia and carbon dioxide. Finally the nitrate contamination of groundwater which enters drinking water and can lead to the potentially fatal blood disorder in infants known as blue baby or methemoglobinemia.

Although the process of nutrient budgeting is the suggested precaution which requires the monitoring of soil conditions and knowledge of the nutrient needs of crops to avoid waste and addition of excess minerals, there are other options which do not place harmful agro-chemicals such as herbicides and pesticides that can cause disease, and that is organic farming. Organic farming quite simply respects nature’s life cycle. Organic farming uses more traditional farming methods such as crop rotation, has strict limits on the use of synthetic pesticides, fertilizers or additives, uses on-site resources such as the manure of livestock as fertilizer and farming crops adapted to the conditions. These farming methods are responsible for the second fastest growing segment in the local food sector having grown 300% from 2004 to 2005. Not only are these methods protecting the natural environment but the initiatives promotes healthier foods that are more nutritious, crops that are more resistant to droughts and the nature of the business has lead to the involvement of previously disadvantaged local farmers.

The chemical fertilizers could, therefore, be said to be diminishing our natural resources. When one factors in the irreversible effect they are having on our ecosystems ones sees that rather than feeding our nation they are causing it to suffer self-inflicted unnecessary destruction of our natural resources with little hope for sustainability. Eco-friendly alternatives do exist that can meet the needs of our environment, economy and growing nation, and need to replace the destructive and careless habits of our past.

(What is organic Farming?), (Fertilizer, 2009), (Perera, 2009), (Sample, 2004),

TOPIC 2: IS THE GAIN IN THE ECONOMIC WEALTH- FOR THE SOUTH AFRICAN CHOR-ALKI INDUSTRIES- WORTH OUR HEALTH?

The industrial production of chlorine, sodium hydroxide and hydrogen

Give schematic diagrams of the three commercial electrolytic cells used to produce chlorine, sodium hydroxide and hydrogen.

For the membrane cell, explain the production process using a flow diagram showing the sequence of the steps of the production process.

(Pillay)

Give the anode and cathode half-reactions, as well as the overall redox reactions. Describe the functions of the membrane in the membrane cell.

Anode half-reaction: 2Cl- → Cl2(g) + 2e-

Cathode half-reaction: 2H2O + 2e- → H2(g) + 2OH-

Overall reaction: 2NaCl + 2H2O → Cl2 + H2 + 2NaOH

The membrane cells allows the cations but not the anions to travel between compartments (half-cells), therefore the sodium ions are able to enter the cathode compartment and react with the pure water.

(Pillay)

Chlorine can be produces industrially by means of three methods. Identify these methods and compare the efficiency of the three cells in terms of power used per metric tonne of chlorine produced.

(Ruth Stringer, 2001)

Identify the risks of operating each of these cells. If you had to advice a chemical company as to which method to use for the production of chlorine, which one would it be.

Both the mercury cell and diaphragm cell are procedures that have risks. While mercury has a low vapour pressure allowing it to be easily evaporated which not only poses a health risk but an environmental one as mercury is a pollutant; asbestos in the diaphragm cell poses health risks to operators who could inhale it. Therefore i would recommend that the membrane cell be utilized because although it as not as energy efficient as the diaphragm and requires very pure brine, it does not pose environmental or health threats.

(CHEMICAL SYSTEMS, 2008), (Chloralkali Industry), (Chlorine Production)

Where in South Africa is chlorine made and what is the name of the manufacturing companies.

NCP manufactures chlorine and operates in Chloorkop Kempton Park Gauteng, getting its electricity from Eskom.

The products of this process

List the benefits of chlorine to human kind (you can also include the product of the chlor-alkali process like PVC). Give special attention to how chlorine safeguard our health despite its dangerous properties.

Chlorine benefits humans in four main areas known as disinfection, pharmaceuticals and medical equipment, public safety as well as crop protection. Chlorine simply cleans. The chlorination of water that removes diseases has increased life expectancy and decreased infant mortality. Chlorine also kills germs such as viruses, bacteria and infections. Not only does chlorine safeguard our health as it is found in or manufactured with 85% of pharmaceuticals, but 96% of crop protection chemicals that ensure low cost nutritious produce contain chlorine. PVC (polyvinyl chloride) is produced using chlorine and is a versatile, lightweight, durable and stain resistant polymer. Other products that use chlorine range from wetsuits to surfboards, golf bags, children’s toys and tennis rackets.

(Howlett, 1995), (Enhancing living standards, 2008)

Describe how soap is made using sodium hydroxide produced in this process. Include the reaction equation.

[image]In industry soap is manufactured by triglycerides (fats if solid at room temperature else oils) which are not soluble in water reacting with sodium hydroxide forming a caustic base. A triglycerides is made up of three carboxylic acids (carbon atom bonded to two oxygen atoms) bonded to glycerol. During the process of saponification the bond between the oxygen atom of the carboxylic acid and carbon atom of the glycerol are broken leaving the oxygen atom to pick up the sodium atom from the sodium hydroxide and result in a fatty acid chain known as soap that is now soluble in water. The reaction is completed once all three fatty acids are removed and the hydroxide has been attached to the glycerol. Ethanol is present during this reaction to lower the activation energy but will evaporate when heated. Salting out then takes place to separate the soap from the glycerol by adding water to improve texture followed by a saturated salt solution such as sodium chloride which glycerol is more soluble in. The soap is then drawn off the top while the glycerol is attained through vacuum distillation.

(Chemical Reactions: Soap Making), (Helmenstine)

Explain the difference between a detergent and soap, giving advantages and disadvantages of each.

The differences in detergents and soaps can be recognised through their ingredients and properties. Soaps are made from natural minerals such as sodium hydroxide and fatty acids while detergents are synthetic and originated in WW2 when oils were scarce and therefore are made from petroleum, foaming agents and alcohol and are heavily scented to disguise their odour. Although soaps are not ideal for acidic condition as in hard water they form a insoluble film that is hard to rinse and turns laundry into a hue while detergents aren’t as reactive to minerals and as a result do not leave a residue. When comparing the two a detergents has the advantage that it lathers better, doesn’t really age remaining stable for long periods and doesn’t leave your clothes dull while soaps while soaps are cheaper, biodegradable and do not tend to pollute as they don’t contain phosphates like detergents.

(Pillay)(Soaps vs Detergents)

Evaluate the impact of the use of detergent to the environment.

Detergents contain phosphates and other chemicals that are washed into waterways. The phosphate is a major source of water pollution and is fed off by phytoplankton and algae which grow in massive numbers, begin to block out sunlight, strip the water of oxygen, and along with the other toxic chemicals are fatal for aquatic life. Detergents are also not biodegradable and can therefore not decompose by natural processes.

(Dishwashing detergent environmental impact, 2009)

How would you advice your family to use detergent so as to be more caring for the environment?

You can be more caring to the environment by reducing the amount of detergent you use and by buying eco-friendly detergent. By adding baking soda to your detergents (laundry or dishwasher) you soften the water and in turn increase the potency of the detergent so less is needed. You can also buy brands that are eco-friendly as they contain less toxic chemicals, are phosphate free and are biodegradable.

(Practical Ways to Keep Your House Clean and Safe)

Where does the chlor-alkali industry in South Africa source its raw materials and energy requirements?

The chlor-alkali industry sources the brine needed off Walvis Bay where sea water is processed through solar evaporation facilities, while the energy requirements are met by Eskom coal plants.

Laboratory simulation

Design an experiment you could use to illustrate the electrolysis of brine. Consider how you would identify the three products of this reaction.

Aim:

Demonstrate the electrolysis of brine and distinguish the products of the reaction.

Hypothesis:

Once connected the electrical energy will be converted to chemical energy as the electrolysis of brine occurs and will produce H2 at the cathode, Cl2 at the anode and Sodium Hydroxide will remain in the solution.

Apparatus:

• Beaker
• Brownlee Electrolysis Apparatus
• Splint
• Bunsen Burner
• Sodium Chloride, Water, HCl

Method:

1. Prepare a brine solution by dissolving the sodium chloride in water.
2. Pour solution into the test tubes of the the Brownlee electrolysis apparatus and tip it into the filled beaker trying to let as little air into the test tubes as possible.
3. Turn on the power and observe what occurs.
4. Once you are satisfied with the amount of gas produced turn the power off.
5. To test if H2 has been produced at the cathode, detach the test tube and hold it over the Bunsen burner and listen for a sound.
6. To test if Cl2 has been produced at the anode, detach the test tube, light a splint and observe what happens when you hold the lit splint in contact with the chlorine gas and watch the flame.
7. To test whether Sodium Chloride is present in the solution, add some HCl to the solution Dip a clean piece of platinum wire into and hold it over a Bunsen burner, observing the colour that appears when burning.

Observation:

• Bubbles formed at both electrodes and as gas was produced the solution in the test tubes was displaced.
• When the gas formed at the cathode was held over the Bunsen burner a popping sound was heard.
• When the gas formed at the anode was held over a glowing splint it was put out.
• When the acid present in solution had HCl added and a platinum wire was dipped in it and held over the Bunsen burner it radiated a yellow orange colour.

Conclusion:

During the electrolysis of brine hydrogen, chlorine and sodium hydroxide were in fact produced.

REDOX REACTIONS

Anode half reaction: 2Cl- - 2e- → Cl2

Cathode half reaction: 2H+ + 2e-→ H2

Nett Reaction: 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g)+ H2(g)

(The Alkali Metals), (Hydroxide Identification)

Concluding Essay

The chlor-alkali industry in South Africa has proven to accumulate wealth at a cost. Through this essay it will be established whether the impacts on our deteriorating health is worth this economic gain.

[image]The chlor-alkali industry produces hydrogen, sodium hydroxide and chlorine. The latter falls in the top ten of chemicals produced and has an extensive range of applications in pharmaceuticals, detergents, deodorants, disinfectants, herbicides, pesticides, and plastics. But it is an organochlorine that carries the characteristics of a toxic, cancer producing and environmentally destructive chemical. The 12 most threatening Persistant Organic Polllutants (POPs) was drawn up by the United Nations, of which all are organochlorines. POPs accumulate through the food web and threaten the health of not only the environment but humans and wildlife too. Included in the priority pollutants are pesticides and products of industrial processes such as dioxins which are produced when chlorine and chlorinated chemicals are produced, heated, processes or burned.

Dioxins contaminate surface water through discharge of dioxin-contaminated waste directly into streams. It is also released into the air from industry which contaminates the soil that through run off reaches the surface water. Since the dioxins aren’t easily dissolved and take long to decompose, they settle in water bodies and as they pass into aquatic organisms they enter the food chain in turn increasing the concentrations further up in the food chain. Their half life ranges from 7 to 11 years making them chemically stable and therefore endured by the body for long periods after being absorbed by the fatty tissues and literally contaminating us. Short term exposure has lead to skin lesions, patchy darkening of the skin and altered liver functions while long term exposure has been shown to affect a range of areas and including our reproduction and development as well as provoking allergic reactions, increasing our risk of cancer and damaging our nervous and immune systems. There is evidence of them effecting unborn children in the embryo resulting in lowered intelligence, poor short-term memory, short attention spans and difficulty with reading. Wildlife’s interest to reproduce is also on a decline as a result of estrogen hormones being mimicked by the dioxins.

There is an alternative to chlorine which has recently surfaced and that is the use of ozone. Even though it dissipates faster than chlorine and requires expensive technology; it doesn’t pose threats upon the environment or our health. Ozone is unlikely to be able to fully replace chlorine but has even been found to perform even better than chlorine in terms of bottle washing, disinfection within the fishing industry, in cooling towers, recycling water, processing vegetables (increasing their shelf life) and oxidising germs and algae in mineral water.

Although the chlor-alkali industry poses health risks, its economic benefits are undeniable. The abundance of raw materials makes the product cheap and its diversity is unparallel as it is used in products like antiseptics, dyes, explosives, foods, insecticides, medicines, metals, paints, paper, plastics, refrigerants, solvents, and textiles to name a few as well as its effective virtual eradication of cholera and typhoid through chlorinated water. Consequently it is not only attractive to the manufacturers but consumers too. As a result the local demand for products of the chlor-alkali industry are ever increasing ,leaving sales revenues exceeding 3 billion Rand and allowing for the further production of other products and economic development of further industries.

Wealth does not have the same worth if it is at the very expense of our health and as there are arising alternatives to the use of these toxic chemicals, it would be unethical and detrimental to our very being to continue production of these chemicals. Chlorine is not only a toxic chemical but the production of it uses enormous amounts of energy, in South Africa’s case from coal plants, and is therefore largely responsible for the abuse of fossil fuels and the high emissions of greenhouse gases that are having a permanent affect on our climate. The wealth gained from the chlor-alkali industry is not worth the risk of our health or the environment of future generations, therefore the continued search for other resources is imperative for our survival.

(Persistant Organic Pollutants), (POPs), (Dioxins), (Chlorine - Properties and uses), (Dioxins and their effects on human health, 2007)

Bibliography

(n.d.). Retrieved April 20, 2009, from Enviro Briefs: http://www.ipni.net/ppiweb/ppibase.nsf/b369c6dbe705dd13852568e3000de93d/0ab5d73c304e9a7948256c5400523ebe/$FILE/Enviro-Brief%201.pdf

Haber Process. (n.d.). Retrieved April 20, 2009, from Wikipedia: http://en.wikipedia.org/wiki/Haber_process#The_Process

A Comparison Of Organic vs. (n.d.). Retrieved June 30, 2009, from The Garden Counselor: http://www.garden-counselor-lawn-care.com/organic-vs-non-organic-fertilizer.html

Advantages and Disadvantages Organic Farming: Good Things, Barriers and Environmental Effects. (n.d.). Retrieved June 30, 2009, from Small Farm Permaculture and Sustainable Living: http://www.small-farm-permaculture-and-sustainable-living.com/advantages_and_disadvantages_organic_farming.html

In B. G. Carl Etnier, Ecological engineering for wastewater treatment (p. 163). CRC Press.

chemguide. (n.d.). Retrieved April 23, 2009, from The Contact Process: http://www.chemguide.co.uk/physical/equilibria/contact.html

Chemical Reactions: Soap Making. (n.d.). Retrieved July 4, 2009, from http://people.cedarville.edu/Employee/gollmers/gsci1020/labs/03g1020lab5.pdf

CHEMICAL SYSTEMS. (2008, July 18). Retrieved July 4, 2009, from http://www.learn.co.za/LC/content/grade12/PHYSICAL%20SCIENCES/LC%20G12%20PHYS%20SC_Lesson28_30.pdf?9062ffa906a3adea3f500f5a7083ca92=126e2aaa03f9d7a698543efdb1d9de46

Chloralkali Industry. (n.d.). Retrieved July 4, 2009, from MLearner: http://www.mlearner.co.za/Chloralkali1.htm

Chlorine - Properties and uses. (n.d.). Retrieved July 7, 2009, from Science Encyclopedia: http://science.jrank.org/pages/1438/Chlorine-Properties-uses-chlorine.html

Chlorine Production. (n.d.). Retrieved July 4, 2009, from Wikipedia: http://en.wikipedia.org/wiki/Chlorine_production#Gas_extraction

Clark, J. (2002). Retrieved April 20, 2009, from chemguide: http://www.chemguide.co.uk/physical/equilibria/haber.html

Cloern, J. E. (2007, December 18). Eutrophication. Retrieved April 23, 2009, from the encyclopedia of earth: http://www.eoearth.org/article/Eutrophication

Cordaro, R. J. (n.d.). Dentrification. Retrieved June 30, 2009, from Wastwater Treatment: http://128.113.2.9/dept/chem-eng/Biotech-Environ/Environmental/denitrification.html

Dioxins. (n.d.). Retrieved July 7, 2009, from Illinois Department of Public Health: http://www.idph.state.il.us/envhealth/factsheets/dioxin.htm

Dioxins and their effects on human health. (2007, November). Retrieved July 7, 2009, from World Health Organization: http://www.who.int/mediacentre/factsheets/fs225/en/index.html

Dishwashing detergent environmental impact. (2009, June). Retrieved July 4, 2009, from Green Living Tips: http://www.greenlivingtips.com/articles/32/1/Dishwashing-detergent-environmental-impact.html

Dredging. (n.d.). Retrieved June 30, 2009, from Wikipedia: http://en.wikipedia.org/wiki/Dredging

Enhancing living standards. (2008, August). Retrieved July 3, 2009, from Chlorine Online: http://www.eurochlor.org/livingstandards

Eutrophication. (2006, May 6). Retrieved April 23, 2009, from New World Encyclopedia: http://www.newworldencyclopedia.org/entry/Eutrophication

Fertilizer. (2009, April 1). Retrieved July 1, 2009, from Chemistry Daily: http://www.chemistrydaily.com/chemistry/Chemical_fertilizers

Foster, N. (n.d.). What is saltpeter. Retrieved April 23, 2009, from Wisegeek: http://www.wisegeek.com/what-is-salt-peter.htm

G.J. van der Linde, M. (2006, February). The South African Fertiliser Industry. Retrieved June 29, 2009, from The Fertilizer Society of South Africa: http://www.fssa.org.za/medialib/Downloads/Home/Articles/THE%20SA%20FERTILISER%20INDUSTRY%20no%202%20Feb06%20AFA%20Conf%20fin.pdf

Helmenstine, A. M. (n.d.). Soap and Saponification . Retrieved July 4, 2009, from About: http://chemistry.about.com/library/weekly/blsapon.htm

Howlett, C. (1995, Septembter 27). Retrieved July 3, 2009, from http://mail.live.com/default.aspx?&ip=10.1.106.216&d=d3980&mf=0&rru=getmsg%3fmsg%3dD482C925%2d4B37%2d46A3%2d9759%2d5B4EF9EAE1E7

Hydroxide Identification. (n.d.). Retrieved July 7, 2009, from ChemBiophys: http://209.85.229.132/search?q=cache:qeTXI22xqtwJ:www.chembiophys.com/Identify%2520chemicals.doc+identify+sodium+hydroxide&cd=8&hl=en&ct=clnk&gl=za

Lucas, J. M. (2008). Physical Science. In J. M. Lucas, The Science Tutor (pp. 108-113,126-131 ). Waterkloof: JNM Publishers.

Manufacturing Nitrates: the Ostwald process. (n.d.). Retrieved April 23, 2009, from http://www.carlton.srsd119.ca/chemical/mtom/contents/chapter3/fritzhaber_2.htm

Mithra, S. (n.d.). What is Guano. Retrieved April 23, 2009, from WiseGeek: http://www.wisegeek.com/what-is-guano.htm

Morgan, D. (n.d.). Retrieved April 20, 2009, from The Orchid House: http://retirees.uwaterloo.ca/~jerry/orchids/nutri.html

Nitric Acid. (n.d.). Retrieved June 30, 2009, from Earth Science from Moorland School: http://www.moorlandschool.co.uk/earth/nitric.htm

Oregon State University. (2008, November 25). Retrieved April 23, 2009, from Human Impacts on Ecosystems: http://oregonstate.edu/~muirp/eutrophi.htm

Ostwald Process. (n.d.). Retrieved June 30, 2009, from Global Oneness: http://www.experiencefestival.com/a/Ostwald_process_-_Description/id/1824492

Perera, Q. (2009, June 26). Replacing chemical fertilizer with organic fertilizer could save millions -Oxfam shows the way. Retrieved July 1, 2009, from Asian Tribune: http://asiantribune.com/06/26/replacing-chemical-fertilizer-with-organic-fertilizer-could-save-millions-oxfam-shows-the-way/

Persistant Organic Pollutants. (n.d.). Retrieved July 7, 2009, from United Nations Environment Project: http://www.chem.unep.ch/pops/

Phytoremediation. (n.d.). Retrieved June 30, 2009, from Wikipedia: http://en.wikipedia.org/wiki/Phytoremediation

POPs. (n.d.). Retrieved July 7, 2009, from United Nations System-Wide Earthwatch: http://earthwatch.unep.ch/emergingissues/toxicchem/pops.php

Potash. (n.d.). Retrieved April 23, 2009, from Wikipedia: http://en.wikipedia.org/wiki/Potash

Practical Ways to Keep Your House Clean and Safe. (n.d.). Retrieved July 4, 2009, from Parenting Bookmark: http://www.parentingbookmark.com/pages/Enviroment01.htm

Ratlabala, M. E. (2003). An Overview of South Africa's Mineral Based Fertilizers. Retrieved June 29, 2009, from Department of Minerals and Energy: http://www.dme.gov.za/pdfs/minerals/r41.pdf

Ruth Stringer, P. J. (2001). Chlorine and the environment . Kluwer Academic Publishers.

Sample, I. (2004, October 9). Global Peril. Guardian .

Sauchelli, V. (1949, July). Industrial and Engineering Chemistry. Retrieved April 23, 2009, from ACS Publications: http://pubs.acs.org/doi/abs/10.1021/ie50475a003

Soaps vs Detergents. (n.d.). Retrieved July 4, 2009, from Detergents and Soaps: http://www.detergentsandsoaps.com/soaps-detergents.html

The advantages and disadvantages of chemical fertilizers. (n.d.). Retrieved June 30, 2009, from WikiAnswers: http://wiki.answers.com/Q/The_advantages_and_disadvantages_of_chemical_fertilizers

The Alkali Metals. (n.d.). Retrieved July 7, 2009, from The Periodic Table: http://www.gcsescience.com/pt12.htm

The Fertilizer Industry. (n.d.). Retrieved April 23, 2009, from Electronic Science Tutor: http://www.physchem.co.za/OB12-sys/fertiliser1.htm

Toxic Substances Hydrology Program . (n.d.). Retrieved April 23, 2009, from USGS: http://toxics.usgs.gov/definitions/eutrophication.html

Troxler, S. (n.d.). Plant Nutrients. Retrieved April 20, 2009, from North Carolina Department of Agriculture and Consumer Servies: http://www.agr.state.nc.us/cyber/kidswrld/plant/nutrient.htm#Nitrogen

What is organic Farming? (n.d.). Retrieved 1 July, 2009, from Organic Farming good for nature good for you: http://ec.europa.eu/agriculture/organic/organic-farming/what-organic_en

Zmaczynski, R. (n.d.). The Effect of the Haber Process on Fertilizers. Retrieved April 23, 2009, from Reading A Machine: http://www.princeton.edu/~hos/mike/texts/readmach/zmaczynski.htm

Sign up and be the first to receive our latest offers: