the attachments below.
To see the document immediately, click on:
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Thursday, August 25, 2011
Friday, August 19, 2011
Short-sightedness and Long-sightedness
Go to site: https://sites.google.com/site/scienceeport/home/short-sightedness-and-long-sightedness and click on the attachment below.
To see the document immediately, go to https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxzY2llbmNlZXBvcnR8Z3g6MWU1ZWRkMzAyNDc4NmRhMg
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Allomerus decemarticulatus ants
(a) Deforestation is an example for human activities in the Amazon Forest. When building homes, factories etc. land is reclaimed and forests are normally burned down. Between May 2000 and August 2006, over 600,000 square kilometers of Amazon rainforest has been destroyed. Brazilian deforestation is strongly associated to the economic health of the country.
A relatively small percentage of large landowners clear vast sections of the Amazon for cattle pastureland. Large areas of forest are cleared and sometimes planted with African savanna grasses for cattle feeding. In many cases, especially during periods of high inflation, land is simply cleared for investment purposes. When pastureland prices exceed forest land prices, forest clearing is a good hedge against inflation.
Such favorable taxation policies, combined with government subsidized agriculture and colonization programs, encourage the destruction of the Amazon. The practice of low taxes on income derived from agriculture and tax rates that favor pasture over forest overvalues agriculture and pastureland and makes it profitable to convert natural forest for these purposes when it normally would not be so.
Up until at least the mid-1990s this system was worsened by the government policy that allowed each claimant to gain title for an amount of land up to three times the amount of forest cleared. A significant amount of deforestation is caused by the subsistence activities of poor farmers who are encouraged to settle on forest lands by government land policies. Poor farmers use fire for clearing land and every year satellite images pick up tens of thousands of fires burning across the Amazon, which burns the Allomerus decemarticulatus ants to death immediately.
Logging in the Amazon is closely linked with road building. Studies by the Environmental Defense Fund show that areas that have been selectively logged are eight times more likely to be settled and cleared by shifting cultivators than untouched rainforests because of access granted to logging roads. Logging roads give colonists access to rainforest, which they exploit for fuelwood, game, building material, and temporary agricultural lands, further destroying the habitat of the Allomerus decemarticulatus ants.
Furthermore, hydroelectric projects have flooded vast areas of Amazon rainforest. The Balbina dam flooded some 2,400 square kilometers (920 square miles) of rainforest when it was completed. This would drown the Allomeerus decemarticulatus ants.
Therefore, this displaces animals, including the Allomerus decemarticulatus ants. Furthermore, as their food source largely depends on making traps using plants to capture insects, deforestation would also mean the loss of traps; hence the ability to capture its prey also decreases tremendously. This will result in the lack of food source for the Allomerus decemarticulatus ants and cause a decrease in its population eventually. Therefore, with no food, the population figures will drop.
(b) The plant is protected by the ants, since the Allomerus decemarticulatus ants capture the insects which might to eat the plant. The plant provides shelter and a platform for the Allomerus decemarticulatus ants to catch prey. Both party benefits. – Mutualism. ***
Mould would benefit since the Allomerus decemarticulatus ants would provide protection for it and sustain it (place to grow) whereas the Allomerus decemarticulatus ants would also benefit since it could catch its prey effectively – thus, since both parties benefit, this proves to be mutualism instead of commensalism or parasitism. – Mutualism.
Mould grows around structure of the plant, but does not affect it. However, the mould in turn finds a place to inhabit. – Commensalism.
When an insect passes overhead, the ants reach up and grab its free legs, wings and antennae, stretching it against the gallery… Swarms of workers then rush over the hapless prey, stinging it into submission. – Exploitative relationship: Predation.
The host farm provides protein, and it has to be shared between the Allomerus decemarticulatus ants and the mould. – Competition.
*** Though not exactly the same, this is similar to the red weevil ants and the macaranga plants or the senduduk plants in Singapore. The macaranga and senduduk plants provide nutrients for ants, and the ants in turn defend the tree from other harmful organisms. While it seems that it is only ants that protect plants from damage, some plants also protect ants. In Singapore, there are palms filled with thorns, and black-coloured ants inhabit it. Thorns in palms would protect ants from predators since predators could not get close to the ants, whereas the ants would too provide protection from palms, since it defend the palms from organisms such as parasites.
References:
http://peeepl.com/gate/index.html?people_id=73801305&to=http%253A%252F%252F2a2science.blogspot.com%252F2011%252F05%252Fhbl-benedict-chin-2a206.html
http://www.mongabay.com/brazil.html
http://2a2science.blogspot.com/
`Toxin free farming - with friendly insects'
Read the newspaper article below and answer the questions below.
Questions
a. Why is Paul Buxman critical of the way some farmers deal with the control of pests?
Paul Buxman feels that farmers should not monitor pesticides by using chemicals fully, since he himself has used not harmful chemicals for nine years since his son developed leukaemia. He did this also because groundwater tests showed chemical levels is 20 time US health levels, and he wanted to prevent this, by using a healthier method of pest monitoring. Also, soil fertility is built naturally by growing cover crops, spreading manure and compost.
b. What is 'integrated pest management'? Is it labour¬-saving or more labour-intensive?
‘Integrated pest management’ is an integrated approach of crop management to solve ecological problems when applied in agriculture. These methods are performed in three stages: prevention, observation, and intervention. It is an ecological approach with a main goal of significantly reducing or eliminating the use of pesticides while at the same time managing pest populations at an acceptable level. This is more labour-intensive than pure chemical usage, since the involvement organic farming requires manpower to monitor the pests.
c. How do insecticides affect bird and worm numbers?
Insecticides decrease the bird and worm numbers.
d. What is meant by `organic farming'?
‘Organic farming’ is the form of agriculture that relies on techniques such as crop rotation, green manure, compost and biological pest control to maintain soil productivity and control pests on a farm.
e. What 'balance of pests and predators' is the article talking about?
The ‘balance of pests and predators’ means that the number of pests and predators are in proportion to what the pyramid of numbers would be like in the natural environment. For example, spiders, ladybugs, praying mantis and the six-spotted thrips (or the predators) would be there to feed on pests such as aphids and mites, while the lacewing eats larvae four times its weight in pests every week.
f. What is meant by `broad spectrum fertilisers'?
‘Broad spectrum fertilisers’ is meant by fertilisers that are effective against a wide variety of microorganisms.
References:
http://bbe-tech.com/bees/2011/06/14/how-does-integrated-pest-management-work-for-you/
http://en.wikipedia.org/wiki/Organic_farming
http://en.wikipedia.org/wiki/Integrated_pest_management
http://www.yourdictionary.com/broad-spectrum
Reflection: Term 3 test results
The recent result I received was 32.5/40, again, an A1 that barely meet the requirements. The test topics ranged from biology to physics, with ecology and refraction and total internal reflection of light, which is combination of facts and application types of questions.
This time, due to time constraint, I had no choice but to compromise my science revision time for other subjects such as Integrated Humanities. As a matter of fact, because my science test is one day right after my Integrated Humanities, and that Integrated Humanities required much more memorization work, I planned that I should only leave one day for my revision for science – in other works, my revision this time was sort of a last minute kind.
However, I already had quite a sufficient understanding on the physic topics due to listening intently during class time, and also because physics mainly required us to think and draw. Either that or we needed to perform some mathematics functions which required the involvement of trigonometry, or the sine, cosine and tangent, in which I quite good at. Therefore, that leaves me with some memorizing work for ecology. I did not actually had quite enough time for practicing, which to me definitely is not negligible, but I had no choice but to make do with it.
As a matter of fact, the main problems I faced in this test is because I did not have enough time to do the bonus question, which many of my classmates obtained marks from. Perhaps, it is because I did not practice enough for my test, thus being slow and insensitive to the methods used to solve trivial questions, thus wasting unnecessary time. There was again careless mistakes, and another blatant error due to not reading the question properly, thus missing out the naming of symbols in a ray diagram.
It was a low A1, but well, at least I managed to maintain my standard!
This time, due to time constraint, I had no choice but to compromise my science revision time for other subjects such as Integrated Humanities. As a matter of fact, because my science test is one day right after my Integrated Humanities, and that Integrated Humanities required much more memorization work, I planned that I should only leave one day for my revision for science – in other works, my revision this time was sort of a last minute kind.
However, I already had quite a sufficient understanding on the physic topics due to listening intently during class time, and also because physics mainly required us to think and draw. Either that or we needed to perform some mathematics functions which required the involvement of trigonometry, or the sine, cosine and tangent, in which I quite good at. Therefore, that leaves me with some memorizing work for ecology. I did not actually had quite enough time for practicing, which to me definitely is not negligible, but I had no choice but to make do with it.
As a matter of fact, the main problems I faced in this test is because I did not have enough time to do the bonus question, which many of my classmates obtained marks from. Perhaps, it is because I did not practice enough for my test, thus being slow and insensitive to the methods used to solve trivial questions, thus wasting unnecessary time. There was again careless mistakes, and another blatant error due to not reading the question properly, thus missing out the naming of symbols in a ray diagram.
It was a low A1, but well, at least I managed to maintain my standard!
Thursday, June 30, 2011
Excursion trip to Nee Soon Swamp Forest
Go to site: https://sites.google.com/site/scienceeport/home/excursion-trip-to-nee-soon-swamp-forest and click on the attachments below to see my excursion trip to Nee Soon Swamp Forest.
Due to some technical difficulties, the alignment of the pictures and words are not in proper. Sorry for the inconvenience caused.
Sulfuric Acid
General background:
Sulfuric acid is a chemical compound H2SO4 that is colorless, odorless, extremely corrosive, oily liquid and is sometimes called oil of vitriol. Balanced equation: H2SO4 H2 + SO42−
Uses of sulfuric acid:
1. Serves as electrolyte in lead-acid storage battery.
a. Acid for this use, containing about 33% H2SO4 and with specific gravity about 1.25, is often called battery acid.
b. Commonly used in motor vehicles.
2. Crucial in the production of fertilizers.
a. Examples: Superphosphate of lime (CaCO3) and ammonium sulfate (NH4)2SO4, which is formed when rock phosphate is treated with sulfuric acid.
3. Used to remove oxides and rusts from iron and steel before plating them with tin or zinc.
4. Dehydrating agent to remove water (only for concentrated sulfuric acid).
a. It has a tendency to form hydrates such as H2SO4.H2O, H2SO4.2H2O, etc.
5. Used to dry neutral and acidic gases.
a. Examples: Nitrogen gas N2, Oxygen gas O2, Carbon dioxide CO2, Sulfur dioxide SO2 etc.
6. Remove water from carbohydrates and some other organic compounds which contain oxygen and hydrogen.
a. Examples: React with sucrose or cane sugar C12H22O11(s) to produce a spongy mass of carbon:
i. C12H22O11(s) + 11H2SO4 12C(s) + 11H2SO4.H2O
7. Used in production of nitroglycerine, an inorganic ester and organic nitrate.
a. Used as an explosive.
b. Used as a vasodilator that is a substance that dilates blood vessels and can be used in the treatment of certain types of heart disease.
8. Used in petroleum refining to wash impurities out of gasoline and other refinery products.
9. Used to make rayon.
10. Use in the manufacturing of other chemicals.
a. Examples: hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes and pigments, explosives, and drugs.
Manufacture of sulfuric acid:
General background: There are two major processes in the manufacturing and production of sulfuric acid, namely the Lead Chamber Process and the Lead Contact Process, with the Lead Chamber Process being the older of the two. The Lead Chamber Process is used to produce much of the acid used to make fertilizers and produces a relatively dilute acid of 62%–78% sulfuric acid whereas the contact process produces a much purer, more concentrated acid but requires purer raw materials and the use of expensive catalysts. Both processes are similar in the oxidized of sulfur dioxide and the dissolving of sulfur dioxide in water.
1. Lead Chamber Process
History
In 1746 John Roebuck developed the Lead Chamber Process for the manufacture of sulfuric acid. Prior to this time, sulfuric acid had been produced in glass bottles several pounds at a time. But the lead chamber process could produce sulfuric acid by the ton. However, this manufacturing process was a batch process and resulted in the consumption of potassium nitrate. In 1835, Joseph Gay-Lussac improved the manufacturing process.
Process
John Roebuck’s Lead Chamber Process:
a) In the original lead chamber process, sulfur and potassium nitrate are ignited in a room lined with lead foil. Potassium nitrate, or saltpeter is an oxidizing agent oxidizes the sulfur to sulfur trioxide.
a. Chemical equation: 6 KNO3(s) + 7 S(s) -----> 3 K2S + 6 NO(g) + 4 SO3(g)
b) The floor of the room was covered with water. When the sulfur trioxide reacted with the water, sulfuric acid was produced.
a. SO3(g) + H2O(l) -----> H2SO4(aq)
Joseph Gay-Lussac’s improvement:
a) A process for recovering the nitrogen in nitrogen monoxide and recycling it to replace the saltpeter as a source of nitrogen was invented.
a. Chemical equation: 4 NO(g) + O2(g) + 2 H2O(l) -----> 4 HNO2(l)
b. Chemical equation: 4 HNO2(l) + 2 SO2(g) -----> 2 H2SO4(aq) + 4 NO(g)
b) Reduced the dependence on expensive saltpeter and sharply reduced nitrogen monoxide emissions.
Lead Chamber Process after improvements:
a) Hot sulfur dioxide gas enters the bottom of a reactor called a Glover tower where it is washed with nitrous vitriol (sulfuric acid with nitric oxide and nitrogen dioxide dissolved in it) and mixed with nitric oxide and nitrogen dioxide gases.
a. Two functions of the Glover tower:
i. Concentration of the chamber acid (62% to 68% H2SO4) is achieved by the hot gases entering the tower which evaporate water from the acid. Some of the sulfur dioxide is oxidized to sulfur trioxide and dissolved in the acid wash to form tower acid or Glover acid (about 78% H2SO4).
ii. Dissolved nitrogen oxides are stripped from the acid and carried with the gas out of the Glover tower into the lead chambers.
b) From the Glover tower, a mixture of gases – including sulfur dioxide and trioxide, nitrogen oxides, nitrogen, oxygen, and steam – is transferred to a lead-lined chamber where it is reacted with more water.
a. Lead-lined chamber: A large, boxlike room or an enclosure in the form of a truncated cone.
b. Sulfuric acid condenses on the walls and collects on the floor of the chamber.
c. The gases pass through each in succession of the three to twelve chambers in a series.
d. The acid produced in the chambers, often called chamber acid or fertilizer acid, contains 62% to 68% H2SO4.
e. Chemical equation: 2 SO2 + O2 + 2 H2O -----> 2 H2SO4
c) After the gases have passed through the chambers they are passed into a reactor called the Gay-Lussac tower where they are washed with cooled concentrated acid from the Glover tower.
a. The nitrogen oxides and unreacted sulfur dioxide dissolve in the acid to form the nitrous vitriol used in the Glover tower.
b. The waste gases exiting the Guy-Lussac tower are usually discharged into the atmosphere.
d) Product acid at a concentration of 78% H2SO4 is drawn from the cooled acid stream that is circulated from the Glover tower to the Guy-Lussac tower. Nitrogen losses are made up with nitric acid which is added to the Glover tower.
2. Contact Process: A process involving the catalytic oxidation of sulfur dioxide, SO2, to sulfur trioxide, SO3.
History
The first observation of a “contact” or heterogeneous catalytic reaction seems to have been made by Edmund Davy in 1817. He noted that heated platinum wire introduced into a mixture of oxygen or air with hydrogen, carbon monoxide, or ethylene became hotter and finally glowed with rapid combustion of the mixture. In 1831 Peregrine Phillips, a vinegar manufacturer in Bristol, England, patented a new process in British Patent No. 6096. The patent described the instantaneous union of sulfur dioxide with atmospheric oxygen when passing the mixture over platinum which had been heated to a strong yellow heat, with the sulfur trioxide formed rapidly absorbed when contacted with water to form sulfuric acid. In spite of the obvious advantages of the contact process over chamber plants for the production of high strength sulfuric acid and oleum used for dyes and nitrocellulose (smokeless powder), the commercial development of the process was extremely slow. Chemical technology of the time, especially involving catalytic reactions, was limited.
Process
a) Solid sulfur, S(s), is burned in air to form sulfur dioxide gas, SO2.
a. Chemical equation: S(s) + O2(g) SO2(g)
b) The gases are mixed with more air then cleaned by electrostatic precipitation to remove any particulate matter.
c) The mixture of sulfur dioxide and air is heated to 450oC and subjected to a pressure of 101.3 - 202.6 kPa (1 -2 atmospheres) in the presence of a catalyst, which is often platinum on a silica/ asbestos carrier/ vanadium pentoxide on a silica carrier (vanadium oxide) to produce sulfur trioxide, SO3(g), with a yield of 98%.
a. Chemical equation: 2SO2(g) + O2(g) 2SO3(g)
d) Any unreacted gases from the above reaction are recycled back into the above reaction.
e) The sulfur trioxide is cooled and passed through two towers.
a. In the first tower, sulfur trioxide, SO3(g) is dissolved in 98% sulfuric acid, H2SO4, to produce disulfuric acid or pyrosulfuric acid, also known as fuming sulfuric acid or oleum, H2S2O7.
i. Chemical equation: SO3(g) + H2SO4 ------> H2S2O7
ii. This is done because when water is added directly to sulfur trioxide to produce sulfuric acid.
iii. Chemical equation: SO3(g) + H2O(l) -----> H2SO4(l)
iv. The reaction is slow and tends to form a mist in which the particles refuse to coalesce (bond).
v. Note: This cannot be done by simply adding water to the sulphur trioxide – the reaction is too uncontrollable that it creates a fog of sulphuric acid.
b. Water is added to the disulfuric acid, H2S2O7, to produce sulfuric acid, H2SO4
c. Chemical equation: H2S2O7(l) + H2O(l) -----> 2H2SO4(l)
d. Note: This can then be reacted safely with water to produce concentrated sulphuric acid - twice as much as you originally used to make the fuming sulphuric acid.
References:
http://www.ausetute.com.au/sulfacid.html
http://www.infoplease.com/ce6/sci/A0861350.html
http://www.infoplease.com/ce6/sci/A0861351.html
http://www.chemguide.co.uk/physical/equilibria/contact.html
www.aiche-cf.org/Clearwater/2008/Paper2/8.2.7.pdf
http://en.wikipedia.org/wiki/Sulfuric_acid
http://web.fccj.org/~ethall/h2so4/h2so4.htm
http://scifun.chem.wisc.edu/chemweek/sulf&top/sulf&top.html
http://www.factmonster.com/ce6/sci/A0861351.html
http://www.factmonster.com/ce6/sci/A0861350.html
http://www.buzzle.com/articles/sulfuric-acid-uses.html
Sulfuric acid is a chemical compound H2SO4 that is colorless, odorless, extremely corrosive, oily liquid and is sometimes called oil of vitriol. Balanced equation: H2SO4 H2 + SO42−
Uses of sulfuric acid:
1. Serves as electrolyte in lead-acid storage battery.
a. Acid for this use, containing about 33% H2SO4 and with specific gravity about 1.25, is often called battery acid.
b. Commonly used in motor vehicles.
2. Crucial in the production of fertilizers.
a. Examples: Superphosphate of lime (CaCO3) and ammonium sulfate (NH4)2SO4, which is formed when rock phosphate is treated with sulfuric acid.
3. Used to remove oxides and rusts from iron and steel before plating them with tin or zinc.
4. Dehydrating agent to remove water (only for concentrated sulfuric acid).
a. It has a tendency to form hydrates such as H2SO4.H2O, H2SO4.2H2O, etc.
5. Used to dry neutral and acidic gases.
a. Examples: Nitrogen gas N2, Oxygen gas O2, Carbon dioxide CO2, Sulfur dioxide SO2 etc.
6. Remove water from carbohydrates and some other organic compounds which contain oxygen and hydrogen.
a. Examples: React with sucrose or cane sugar C12H22O11(s) to produce a spongy mass of carbon:
i. C12H22O11(s) + 11H2SO4 12C(s) + 11H2SO4.H2O
7. Used in production of nitroglycerine, an inorganic ester and organic nitrate.
a. Used as an explosive.
b. Used as a vasodilator that is a substance that dilates blood vessels and can be used in the treatment of certain types of heart disease.
8. Used in petroleum refining to wash impurities out of gasoline and other refinery products.
9. Used to make rayon.
10. Use in the manufacturing of other chemicals.
a. Examples: hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes and pigments, explosives, and drugs.
Manufacture of sulfuric acid:
General background: There are two major processes in the manufacturing and production of sulfuric acid, namely the Lead Chamber Process and the Lead Contact Process, with the Lead Chamber Process being the older of the two. The Lead Chamber Process is used to produce much of the acid used to make fertilizers and produces a relatively dilute acid of 62%–78% sulfuric acid whereas the contact process produces a much purer, more concentrated acid but requires purer raw materials and the use of expensive catalysts. Both processes are similar in the oxidized of sulfur dioxide and the dissolving of sulfur dioxide in water.
1. Lead Chamber Process
History
In 1746 John Roebuck developed the Lead Chamber Process for the manufacture of sulfuric acid. Prior to this time, sulfuric acid had been produced in glass bottles several pounds at a time. But the lead chamber process could produce sulfuric acid by the ton. However, this manufacturing process was a batch process and resulted in the consumption of potassium nitrate. In 1835, Joseph Gay-Lussac improved the manufacturing process.
Process
John Roebuck’s Lead Chamber Process:
a) In the original lead chamber process, sulfur and potassium nitrate are ignited in a room lined with lead foil. Potassium nitrate, or saltpeter is an oxidizing agent oxidizes the sulfur to sulfur trioxide.
a. Chemical equation: 6 KNO3(s) + 7 S(s) -----> 3 K2S + 6 NO(g) + 4 SO3(g)
b) The floor of the room was covered with water. When the sulfur trioxide reacted with the water, sulfuric acid was produced.
a. SO3(g) + H2O(l) -----> H2SO4(aq)
Joseph Gay-Lussac’s improvement:
a) A process for recovering the nitrogen in nitrogen monoxide and recycling it to replace the saltpeter as a source of nitrogen was invented.
a. Chemical equation: 4 NO(g) + O2(g) + 2 H2O(l) -----> 4 HNO2(l)
b. Chemical equation: 4 HNO2(l) + 2 SO2(g) -----> 2 H2SO4(aq) + 4 NO(g)
b) Reduced the dependence on expensive saltpeter and sharply reduced nitrogen monoxide emissions.
Lead Chamber Process after improvements:
a) Hot sulfur dioxide gas enters the bottom of a reactor called a Glover tower where it is washed with nitrous vitriol (sulfuric acid with nitric oxide and nitrogen dioxide dissolved in it) and mixed with nitric oxide and nitrogen dioxide gases.
a. Two functions of the Glover tower:
i. Concentration of the chamber acid (62% to 68% H2SO4) is achieved by the hot gases entering the tower which evaporate water from the acid. Some of the sulfur dioxide is oxidized to sulfur trioxide and dissolved in the acid wash to form tower acid or Glover acid (about 78% H2SO4).
ii. Dissolved nitrogen oxides are stripped from the acid and carried with the gas out of the Glover tower into the lead chambers.
b) From the Glover tower, a mixture of gases – including sulfur dioxide and trioxide, nitrogen oxides, nitrogen, oxygen, and steam – is transferred to a lead-lined chamber where it is reacted with more water.
a. Lead-lined chamber: A large, boxlike room or an enclosure in the form of a truncated cone.
b. Sulfuric acid condenses on the walls and collects on the floor of the chamber.
c. The gases pass through each in succession of the three to twelve chambers in a series.
d. The acid produced in the chambers, often called chamber acid or fertilizer acid, contains 62% to 68% H2SO4.
e. Chemical equation: 2 SO2 + O2 + 2 H2O -----> 2 H2SO4
c) After the gases have passed through the chambers they are passed into a reactor called the Gay-Lussac tower where they are washed with cooled concentrated acid from the Glover tower.
a. The nitrogen oxides and unreacted sulfur dioxide dissolve in the acid to form the nitrous vitriol used in the Glover tower.
b. The waste gases exiting the Guy-Lussac tower are usually discharged into the atmosphere.
d) Product acid at a concentration of 78% H2SO4 is drawn from the cooled acid stream that is circulated from the Glover tower to the Guy-Lussac tower. Nitrogen losses are made up with nitric acid which is added to the Glover tower.
2. Contact Process: A process involving the catalytic oxidation of sulfur dioxide, SO2, to sulfur trioxide, SO3.
History
The first observation of a “contact” or heterogeneous catalytic reaction seems to have been made by Edmund Davy in 1817. He noted that heated platinum wire introduced into a mixture of oxygen or air with hydrogen, carbon monoxide, or ethylene became hotter and finally glowed with rapid combustion of the mixture. In 1831 Peregrine Phillips, a vinegar manufacturer in Bristol, England, patented a new process in British Patent No. 6096. The patent described the instantaneous union of sulfur dioxide with atmospheric oxygen when passing the mixture over platinum which had been heated to a strong yellow heat, with the sulfur trioxide formed rapidly absorbed when contacted with water to form sulfuric acid. In spite of the obvious advantages of the contact process over chamber plants for the production of high strength sulfuric acid and oleum used for dyes and nitrocellulose (smokeless powder), the commercial development of the process was extremely slow. Chemical technology of the time, especially involving catalytic reactions, was limited.
Process
a) Solid sulfur, S(s), is burned in air to form sulfur dioxide gas, SO2.
a. Chemical equation: S(s) + O2(g) SO2(g)
b) The gases are mixed with more air then cleaned by electrostatic precipitation to remove any particulate matter.
c) The mixture of sulfur dioxide and air is heated to 450oC and subjected to a pressure of 101.3 - 202.6 kPa (1 -2 atmospheres) in the presence of a catalyst, which is often platinum on a silica/ asbestos carrier/ vanadium pentoxide on a silica carrier (vanadium oxide) to produce sulfur trioxide, SO3(g), with a yield of 98%.
a. Chemical equation: 2SO2(g) + O2(g) 2SO3(g)
d) Any unreacted gases from the above reaction are recycled back into the above reaction.
e) The sulfur trioxide is cooled and passed through two towers.
a. In the first tower, sulfur trioxide, SO3(g) is dissolved in 98% sulfuric acid, H2SO4, to produce disulfuric acid or pyrosulfuric acid, also known as fuming sulfuric acid or oleum, H2S2O7.
i. Chemical equation: SO3(g) + H2SO4 ------> H2S2O7
ii. This is done because when water is added directly to sulfur trioxide to produce sulfuric acid.
iii. Chemical equation: SO3(g) + H2O(l) -----> H2SO4(l)
iv. The reaction is slow and tends to form a mist in which the particles refuse to coalesce (bond).
v. Note: This cannot be done by simply adding water to the sulphur trioxide – the reaction is too uncontrollable that it creates a fog of sulphuric acid.
b. Water is added to the disulfuric acid, H2S2O7, to produce sulfuric acid, H2SO4
c. Chemical equation: H2S2O7(l) + H2O(l) -----> 2H2SO4(l)
d. Note: This can then be reacted safely with water to produce concentrated sulphuric acid - twice as much as you originally used to make the fuming sulphuric acid.
References:
http://www.ausetute.com.au/sulfacid.html
http://www.infoplease.com/ce6/sci/A0861350.html
http://www.infoplease.com/ce6/sci/A0861351.html
http://www.chemguide.co.uk/physical/equilibria/contact.html
www.aiche-cf.org/Clearwater/2008/Paper2/8.2.7.pdf
http://en.wikipedia.org/wiki/Sulfuric_acid
http://web.fccj.org/~ethall/h2so4/h2so4.htm
http://scifun.chem.wisc.edu/chemweek/sulf&top/sulf&top.html
http://www.factmonster.com/ce6/sci/A0861351.html
http://www.factmonster.com/ce6/sci/A0861350.html
http://www.buzzle.com/articles/sulfuric-acid-uses.html
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