Wednesday, December 14, 2011
Wednesday, April 23, 2008
Cracking AIEEE Tips from Orkut AIEEE community
http://www.orkut.com/CommMsgs.aspx?cmm=10597861&tid=2593734643528395271
ABHI: Feel the
How can u crack AIEEE
Hi everyone. I am abhishek. I cracked AIEEE last year. Now I would like to tell you all how an average student can crack AIEEE if he plans in a proper way.
Some rules to crack any comp exam..
You must have a deep knowledge of the syllabus.
You must have done deep analysis of the exam
You must have seen the changing pattern of the exam in last few years
You must have a right strategy for the exam
You must be confident to crack it
Most importantly dont panic, No one is perfect. Stay calm on the exam day....
---------
Now talking about AIEEE exam. Cracking AIEEE or not totally depends on time management while giving exam. For it right choice of the questions must be done so that you dont waste time on difficult question and leaving them without getting the answer and wasting 1 to 2 minutes. Remember most of the student dont clear AIEEE b'coz they make this mistake....
If you see the AIEEE 2007 paper you will find that there were 120 questions each carrying 3 marks. The total marks were 360 out of which if you had scored 200+ marks you were always safe to get a good college,. After doing a deep analysis of the last year paper I have found that in physics most of the questions were from electricity, magnetism, modern physics and mechanics.
About 75 to 80% paper was covered from these topics. 35% questions were easy and 60% were medium. So if you attempt 65% questions ie 26 questions with 4 wrong out of 40. This means your score is 76-4=72 marks. Now these 26 questions you had to do in 50 minutes. means 2 minutes for each question which is quite a fair time to solve the questions as some of the questions are conceptual. So if you can attempt your mocks by following this strategy for physics it will help you and try to implement it in your AIEEE exam...
Talking about chemistry, This is the most broad branch but scoring one,
Doing analysis of last year. Physical chemistry had 21 questions, organic 12 and inorganic 7. What this shows that physical chemistry is the most important part to crack AIEEE as the examiners love it to put it in Question paper. student also try to put too much time in doing organic and leaving Physical..
---------
Important topics for Physical chemistry
Atomic structure and chemical bonding 4 questions
Thermodynamics 4 questions
Equilibrium 3 questions
Nuclear chemistry and electro chemistry 2 questions each.
They consist 15 questions out of which if you are doing 12 questions out of which 10 are right.
your score for physical is 28.
Talking about Organic chemistry
Organic chemistry- basic principles 2 questions
Stereochemistry 2 questions
Hydrocarbons 2 questions
If you are attempting 10 questions in this section having 8 right. your score for this section is 22.
Talking about inorganic part. p , d and f block are most important. Still if your are sticking with these three topics, you are able to do 8 questions. Assuming your score for this section is 22.
Lets doing the total of your score for Chemistry 28+22+22=72
---------------
Now comes the most difficult part. MATHS
Doing the analysis. I have found that calculus and algebra are the most coming topics in the previous year papers of AIEEE. Last year 20 questions were there from these two topics. If you had attempted 14 questions with 11 right and 3 wrong from these two topics. Your score was 30 in this part.And if you had spent 30 minutes for these 14 questions. you were still left with 20-25 minutes. You should had gone for 3D, vectors and cordinate geometry. These three topics had 12 questions and if you had done 8 questions in remaining 20 minutes qith 6 right. Your score for these topics was 14 making your total score for Maths 44. This is a rough calculation. Score of 50 can be easily obtained.
------------
So your total score in AIEEE is 72+72+50= 194 which could had easily fetched a seat in a very nice institute.
--------------
One more important thing for you all.......
Never attempt maths first. It will surely ruin your performance in the exam.....
Try to attempt chemistry in the first hour as it has some easy questions and if you can solve these question in the first hour, you will feel confident with more accuracy,. this has been proved that if you are confident then your efficiency increases,,,,,,,,,
-----------
inorganic and organic also cover huge part in AIEEE exam. What I think is that most important thing is how can u get through cut off. This can be done alone with organic and inorganic. As you also know that chemistry is the most scoring of all.. Do one thing just read the concepts of thermodynamics and chemical equilibrium. You can see that some questions from these parts are just conceptual type. So just clear your concepts and you can do 40% questions from these two topics.
Believe me those who crack AIEEE are those who does well in chemistry. In these coming days concentrate more on chemistry. If you are studying 10 hours a day. Study atleast 4 hours for chemistry. With in these 4 hours brush up your concepts of organic and inorganic for 3 hours and give 1 hour for physical. If after this you can do 8 questions from physical and as you said you are good in organic and inorganic then you can do better in these sections. Then surely you are clearing your Cut off for Chemistry.
Always do theoretical questions firstly and after this question which require calculation. its a nature of human that if you do few questions in the beginning then positive energy will come inside you and your efficiency will increase.....
Never attempt numerical questions in the first 10 or 15 minutes of your exam.......
-------------------
Talking about mocks. Do 5 mocks before exam. It will help you to know where are you wasting your time in doing the exam. Dude do mocks. They are most important to crack AIEEE
---------------------
Tomorrow is 18th, leaving day before AIEEE you are left with 8 days. Do one thing revise all the formulas and the important points which you have marked within these 8 days. Remember that study all three subjects everyday. I hope that you have marked important points. Make a time table for the coming six days to revise your syllabus. Time table must be like that you are giving max time to your strengths. Like if your strength in Physics is Electrostatics then revise electro giving enough time to it so that you are sure about every concept about it. If you are not sure about modern physics then whatever you have studied about it, study it. Dont study anything new about anything.
Try to cover your syllabus within next 6 days. Now you have revise your syllabus once.
On seventh day, do two mocks before night. Try to analyze where are you making mistakes, I mean where are you wasting your time. Which section you are doing best. Whatever mistakes you make in first paper try to remove in second. In this you will be better prepared for the main exam. What most students do is that they revise whole of the syllabus but never attempt a mock and thus they always make mistake in main exam and thus they loose the track..
After this at night and on 8th day again revise some important points or you can mark some important points on these six days to revise on the 8th day.
After this, on day before AIEEE dont study anything. Calm yourself, Say to yourself I am excited about AIEEE and I can crack it easily. Go to temple and play with your friends. Dont talk anything about AIEEE with others. Dont ask your friend how much they have studied. It will cause much pressure. You can even watch a film on 26th.
Then sleep for atleast 8 hours and go to your center with full confidence.
Cracking any exam depends on two things
How you study
Your attitude....
-----------------
For maths, I would recommend you R.D sharma objective. This is a very good book. Every type of questions are covered in this book.
For Physics H.C verma is best book to clear your concepts. After attempting questions from it you can take any objective book or AIEEE explorer and search for the questions in the net. There are some magzines like Physics Today which will help you in doing mocks and new questions. This is a monthly magzine which must be done. It is a very nice one.
For chemistry study NCERT book. Well I believe that chemistry portion in AIEEE is more conceptual paper than numerical, so I believe that P. Bahadur will not help you upto huge level . But still do short questions from it rather than trying big numerical from it.
----------------------
ABHI: Feel the
How can u crack AIEEE
Hi everyone. I am abhishek. I cracked AIEEE last year. Now I would like to tell you all how an average student can crack AIEEE if he plans in a proper way.
Some rules to crack any comp exam..
You must have a deep knowledge of the syllabus.
You must have done deep analysis of the exam
You must have seen the changing pattern of the exam in last few years
You must have a right strategy for the exam
You must be confident to crack it
Most importantly dont panic, No one is perfect. Stay calm on the exam day....
---------
Now talking about AIEEE exam. Cracking AIEEE or not totally depends on time management while giving exam. For it right choice of the questions must be done so that you dont waste time on difficult question and leaving them without getting the answer and wasting 1 to 2 minutes. Remember most of the student dont clear AIEEE b'coz they make this mistake....
If you see the AIEEE 2007 paper you will find that there were 120 questions each carrying 3 marks. The total marks were 360 out of which if you had scored 200+ marks you were always safe to get a good college,. After doing a deep analysis of the last year paper I have found that in physics most of the questions were from electricity, magnetism, modern physics and mechanics.
About 75 to 80% paper was covered from these topics. 35% questions were easy and 60% were medium. So if you attempt 65% questions ie 26 questions with 4 wrong out of 40. This means your score is 76-4=72 marks. Now these 26 questions you had to do in 50 minutes. means 2 minutes for each question which is quite a fair time to solve the questions as some of the questions are conceptual. So if you can attempt your mocks by following this strategy for physics it will help you and try to implement it in your AIEEE exam...
Talking about chemistry, This is the most broad branch but scoring one,
Doing analysis of last year. Physical chemistry had 21 questions, organic 12 and inorganic 7. What this shows that physical chemistry is the most important part to crack AIEEE as the examiners love it to put it in Question paper. student also try to put too much time in doing organic and leaving Physical..
---------
Important topics for Physical chemistry
Atomic structure and chemical bonding 4 questions
Thermodynamics 4 questions
Equilibrium 3 questions
Nuclear chemistry and electro chemistry 2 questions each.
They consist 15 questions out of which if you are doing 12 questions out of which 10 are right.
your score for physical is 28.
Talking about Organic chemistry
Organic chemistry- basic principles 2 questions
Stereochemistry 2 questions
Hydrocarbons 2 questions
If you are attempting 10 questions in this section having 8 right. your score for this section is 22.
Talking about inorganic part. p , d and f block are most important. Still if your are sticking with these three topics, you are able to do 8 questions. Assuming your score for this section is 22.
Lets doing the total of your score for Chemistry 28+22+22=72
---------------
Now comes the most difficult part. MATHS
Doing the analysis. I have found that calculus and algebra are the most coming topics in the previous year papers of AIEEE. Last year 20 questions were there from these two topics. If you had attempted 14 questions with 11 right and 3 wrong from these two topics. Your score was 30 in this part.And if you had spent 30 minutes for these 14 questions. you were still left with 20-25 minutes. You should had gone for 3D, vectors and cordinate geometry. These three topics had 12 questions and if you had done 8 questions in remaining 20 minutes qith 6 right. Your score for these topics was 14 making your total score for Maths 44. This is a rough calculation. Score of 50 can be easily obtained.
------------
So your total score in AIEEE is 72+72+50= 194 which could had easily fetched a seat in a very nice institute.
--------------
One more important thing for you all.......
Never attempt maths first. It will surely ruin your performance in the exam.....
Try to attempt chemistry in the first hour as it has some easy questions and if you can solve these question in the first hour, you will feel confident with more accuracy,. this has been proved that if you are confident then your efficiency increases,,,,,,,,,
-----------
inorganic and organic also cover huge part in AIEEE exam. What I think is that most important thing is how can u get through cut off. This can be done alone with organic and inorganic. As you also know that chemistry is the most scoring of all.. Do one thing just read the concepts of thermodynamics and chemical equilibrium. You can see that some questions from these parts are just conceptual type. So just clear your concepts and you can do 40% questions from these two topics.
Believe me those who crack AIEEE are those who does well in chemistry. In these coming days concentrate more on chemistry. If you are studying 10 hours a day. Study atleast 4 hours for chemistry. With in these 4 hours brush up your concepts of organic and inorganic for 3 hours and give 1 hour for physical. If after this you can do 8 questions from physical and as you said you are good in organic and inorganic then you can do better in these sections. Then surely you are clearing your Cut off for Chemistry.
Always do theoretical questions firstly and after this question which require calculation. its a nature of human that if you do few questions in the beginning then positive energy will come inside you and your efficiency will increase.....
Never attempt numerical questions in the first 10 or 15 minutes of your exam.......
-------------------
Talking about mocks. Do 5 mocks before exam. It will help you to know where are you wasting your time in doing the exam. Dude do mocks. They are most important to crack AIEEE
---------------------
Tomorrow is 18th, leaving day before AIEEE you are left with 8 days. Do one thing revise all the formulas and the important points which you have marked within these 8 days. Remember that study all three subjects everyday. I hope that you have marked important points. Make a time table for the coming six days to revise your syllabus. Time table must be like that you are giving max time to your strengths. Like if your strength in Physics is Electrostatics then revise electro giving enough time to it so that you are sure about every concept about it. If you are not sure about modern physics then whatever you have studied about it, study it. Dont study anything new about anything.
Try to cover your syllabus within next 6 days. Now you have revise your syllabus once.
On seventh day, do two mocks before night. Try to analyze where are you making mistakes, I mean where are you wasting your time. Which section you are doing best. Whatever mistakes you make in first paper try to remove in second. In this you will be better prepared for the main exam. What most students do is that they revise whole of the syllabus but never attempt a mock and thus they always make mistake in main exam and thus they loose the track..
After this at night and on 8th day again revise some important points or you can mark some important points on these six days to revise on the 8th day.
After this, on day before AIEEE dont study anything. Calm yourself, Say to yourself I am excited about AIEEE and I can crack it easily. Go to temple and play with your friends. Dont talk anything about AIEEE with others. Dont ask your friend how much they have studied. It will cause much pressure. You can even watch a film on 26th.
Then sleep for atleast 8 hours and go to your center with full confidence.
Cracking any exam depends on two things
How you study
Your attitude....
-----------------
For maths, I would recommend you R.D sharma objective. This is a very good book. Every type of questions are covered in this book.
For Physics H.C verma is best book to clear your concepts. After attempting questions from it you can take any objective book or AIEEE explorer and search for the questions in the net. There are some magzines like Physics Today which will help you in doing mocks and new questions. This is a monthly magzine which must be done. It is a very nice one.
For chemistry study NCERT book. Well I believe that chemistry portion in AIEEE is more conceptual paper than numerical, so I believe that P. Bahadur will not help you upto huge level . But still do short questions from it rather than trying big numerical from it.
----------------------
AIEEE Model paper published in eenadu 19 April 2009
http://www.eenadu.net/pratibhaplus/prati03.pdf
http://www.eenadu.net/pratibhaplus/prati04.pdf
http://www.eenadu.net/pratibhaplus/prati05.pdf
http://www.eenadu.net/pratibhaplus/prati08.pdf
http://www.eenadu.net/pratibhaplus/prati09.pdf
http://www.eenadu.net/pratibhaplus/prati10.pdf
http://www.eenadu.net/pratibhaplus/prati11.pdf
Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf
Model Paper II
http://www.eenadu.net/pratibhaplus/prati14.pdf
http://www.eenadu.net/pratibhaplus/prati15.pdf
http://www.eenadu.net/pratibhaplus/prati16.pdf
http://www.eenadu.net/pratibhaplus/prati17.pdf
http://www.eenadu.net/pratibhaplus/prati20.pdf
http://www.eenadu.net/pratibhaplus/prati21.pdf
http://www.eenadu.net/pratibhaplus/prati22.pdf
Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf
http://www.eenadu.net/pratibhaplus/prati04.pdf
http://www.eenadu.net/pratibhaplus/prati05.pdf
http://www.eenadu.net/pratibhaplus/prati08.pdf
http://www.eenadu.net/pratibhaplus/prati09.pdf
http://www.eenadu.net/pratibhaplus/prati10.pdf
http://www.eenadu.net/pratibhaplus/prati11.pdf
Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf
Model Paper II
http://www.eenadu.net/pratibhaplus/prati14.pdf
http://www.eenadu.net/pratibhaplus/prati15.pdf
http://www.eenadu.net/pratibhaplus/prati16.pdf
http://www.eenadu.net/pratibhaplus/prati17.pdf
http://www.eenadu.net/pratibhaplus/prati20.pdf
http://www.eenadu.net/pratibhaplus/prati21.pdf
http://www.eenadu.net/pratibhaplus/prati22.pdf
Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf
Wednesday, February 13, 2008
AIEEE Chemistry Unit 13 Hydrogen
UNIT 13 HYDROGEN
Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen;
----------------
Period 1 Group 1
Atomic Number 1
Symbol H
Atomic Weight 1.0079
Discovery Cavendish, 1766
Hydrogen was prepared for many years before it was recognized as a distinct element.
Electron Configuration 1s¹
Word Origin Greek: hydro, water; genes, forming
Named by Lavoisier.
Isotopes
Protium (0 neutrons), Deuterium (1 neutron), and Tritium (2 neutrons).
Properties
Hydrogen is the most abundant element in the universe.
Hydrogen is a colorless, odorless, combustible gas.
Hydrogen gas is so light and diffusive that uncombined hydrogen can escape from the atmosphere.
Hydrogen gas ordinarily is a mixture of two molecular forms, ortho- and para-hydrogen, which differ by the spins of their electrons and nuclei.
Normal hydrogen at room temperature consists of 25% of the para form and 75% of the ortho form. The ortho form cannot be prepared in the pure state. Since the two forms of hydrogen differ in energy, their physical properties also differ.
Uses
Hydrogen is important in the proton-proton reaction and carbon-nitrogen cycle. Liquid hydrogen is used in cryogenics and in the study of superconductivity.
Great quantities are used for the fixation of nitrogen from the air in the Haber ammonia process.
Hydrogen is use in welding, for the hydrogenation of fats and oils, in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization.
Other applications include producing rocket fuel, filling balloons, making fuel cells, producing hydrochloric acid, and reducing metallic ores.
Deuterium is used as a moderator to slow down neutrons and as a tracer.
Tritium is used in the production of the hydrogen (fusion) bomb.
Tritium is also used in making luminous paints and as a tracer.
Sources
Hydrogen occurs in the free state in volcanic gases and some natural gases. Hydrogen is prepared by steam on heated carbon, decomposition of certain hydrocarbons with heat, action of sodium or potassium hydroxide on aluminum electrolysis of water, or displacement from acids by certain metals.
Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen;
----------------
Period 1 Group 1
Atomic Number 1
Symbol H
Atomic Weight 1.0079
Discovery Cavendish, 1766
Hydrogen was prepared for many years before it was recognized as a distinct element.
Electron Configuration 1s¹
Word Origin Greek: hydro, water; genes, forming
Named by Lavoisier.
Isotopes
Protium (0 neutrons), Deuterium (1 neutron), and Tritium (2 neutrons).
Properties
Hydrogen is the most abundant element in the universe.
Hydrogen is a colorless, odorless, combustible gas.
Hydrogen gas is so light and diffusive that uncombined hydrogen can escape from the atmosphere.
Hydrogen gas ordinarily is a mixture of two molecular forms, ortho- and para-hydrogen, which differ by the spins of their electrons and nuclei.
Normal hydrogen at room temperature consists of 25% of the para form and 75% of the ortho form. The ortho form cannot be prepared in the pure state. Since the two forms of hydrogen differ in energy, their physical properties also differ.
Uses
Hydrogen is important in the proton-proton reaction and carbon-nitrogen cycle. Liquid hydrogen is used in cryogenics and in the study of superconductivity.
Great quantities are used for the fixation of nitrogen from the air in the Haber ammonia process.
Hydrogen is use in welding, for the hydrogenation of fats and oils, in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization.
Other applications include producing rocket fuel, filling balloons, making fuel cells, producing hydrochloric acid, and reducing metallic ores.
Deuterium is used as a moderator to slow down neutrons and as a tracer.
Tritium is used in the production of the hydrogen (fusion) bomb.
Tritium is also used in making luminous paints and as a tracer.
Sources
Hydrogen occurs in the free state in volcanic gases and some natural gases. Hydrogen is prepared by steam on heated carbon, decomposition of certain hydrocarbons with heat, action of sodium or potassium hydroxide on aluminum electrolysis of water, or displacement from acids by certain metals.
AIEEE Chemistry Unit 13B Water and Heavy Water
Physical and chemical properties of water and heavy water;
Heavy water is water that contains the heavy isotope of hydrogen called deuterium (chemical symbol D). The deuterium atom weighs about twice as much as ordinary hydrogen atom. Heavy water, also called deuterium oxide, makes up about 1 part in 5000 of ordinary water.
It was first separated from ordinary water in 1932 by G N Lewis, a chemist at the University of California.
Because of the difference between the weights of the two kinds of hydrogen atoms, the physical properties of heavy water differ from those of ordinary water. Heavy water freezes at 3.82oC and boils at 101.42oC.
Ice made from heavy water sinks in normal water.
Heavy water is useful in some kinds of nuclear reactors. It acts as a moderator to control the energy of the neutrons in a chain reaction. Seeds will not germinate in heavy water, and some animals, including tadpoles, cannot live in it.
Heavy water is water that contains the heavy isotope of hydrogen called deuterium (chemical symbol D). The deuterium atom weighs about twice as much as ordinary hydrogen atom. Heavy water, also called deuterium oxide, makes up about 1 part in 5000 of ordinary water.
It was first separated from ordinary water in 1932 by G N Lewis, a chemist at the University of California.
Because of the difference between the weights of the two kinds of hydrogen atoms, the physical properties of heavy water differ from those of ordinary water. Heavy water freezes at 3.82oC and boils at 101.42oC.
Ice made from heavy water sinks in normal water.
Heavy water is useful in some kinds of nuclear reactors. It acts as a moderator to control the energy of the neutrons in a chain reaction. Seeds will not germinate in heavy water, and some animals, including tadpoles, cannot live in it.
Unit 13C Hydrogen Peroxide
Structure, preparation, reactions and uses of hydrogen peroxide;
Hydrogen peroxide, H2O2, was first discovered by Thenard among others in 1818 by reacting acids with barium peroxide, BaO2.
It resembles water in appearance being colourless in small quantities but blue when observed in thick layers.
It decomposes to oxygen and water and this decomposition is promoted by heat and alkalis.
Commercial grade H2O2 usually contains small amounts of stabilizers.
Hydrogen peroxide is a strong oxidising agent and is widely used as a bleaching agent. In dilute solutions it is an efficient antiseptic. The uses of hydrogen peroxide have been changing in recent years.
Uses
Textile bleaching
Chemical production
Wood pulp bleaching - Major user
Environmental uses
Miscellaneous uses
Production process
Hydrogen peroxide is produced by reducing alkylanthraquinone with hydrogen in the presence of a catalyst to the hydroquinone. After the catalyst has been removed to prevent decomposition of the hydrogen peroxide, the hydroquinone is oxidised, usually with air, back to quinone with a resultant co-production of hydrogen peroxide.
The hydrogen peroxide is removed and purified and the quinone is regenerated and returned to the reaction.
The anthraquinone must be dissolved in a suitable solvent for the hydrogenation, oxidation and extraction steps - this is usually referred to as the working solution. The solvent is usually a mixture because quinones dissolve readily in non-polar aromatic solvents, such as alkylbenzene, whereas hydroquinones dissolve well in polar solvents, such as alcohols and esters. A variety of different mixtures are in use but the aim is to satisfy a number of criteria, namely good solubility of both quinone and hydroquinone, good stability in both hydrogenator and oxidiser, low solubility in water and aqueous hydrogen peroxide solutions, sufficiently higher or lower density than water to ensure separation of the two phases during extraction, low volatility, high distribution coefficient for hydrogen peroxide in the solvent-water system and low toxicity. 1
In the hydrogenator, the working solution is reacted with hydrogen in the presence of a catalyst. The process is exothermic and the heat of reaction is removed by cooling the working solution before it enters the hydrogenator, by cooling the reactor during hydrogenation and/or by cooling the hydrogenated working solution.
After the hydrogenation reaction, the working solution must pass through a filtration stage to remove all traces of catalyst. Even small traces of catalyst in the oxidation and extraction stages lead to significant losses of hydrogen peroxide and could present safety problems. During the oxidation stage, air is passed through the hydrogenated working solution to convert the dissolved hydroquinones to quinones and form the hydrogen peroxide. The air outlet is passed over activated carbon adsorbers to recover solvent.
Crude hydrogen peroxide is extracted from the oxidised working solution by treating with water. The working solution is then regenerated and fed back to the front of the process and the crude hydrogen peroxide (15-35 wt%) is fed to a treatment unit where the concentration is increased to 50-70 wt%.
Hydrogen peroxide, H2O2, was first discovered by Thenard among others in 1818 by reacting acids with barium peroxide, BaO2.
It resembles water in appearance being colourless in small quantities but blue when observed in thick layers.
It decomposes to oxygen and water and this decomposition is promoted by heat and alkalis.
Commercial grade H2O2 usually contains small amounts of stabilizers.
Hydrogen peroxide is a strong oxidising agent and is widely used as a bleaching agent. In dilute solutions it is an efficient antiseptic. The uses of hydrogen peroxide have been changing in recent years.
Uses
Textile bleaching
Chemical production
Wood pulp bleaching - Major user
Environmental uses
Miscellaneous uses
Production process
Hydrogen peroxide is produced by reducing alkylanthraquinone with hydrogen in the presence of a catalyst to the hydroquinone. After the catalyst has been removed to prevent decomposition of the hydrogen peroxide, the hydroquinone is oxidised, usually with air, back to quinone with a resultant co-production of hydrogen peroxide.
The hydrogen peroxide is removed and purified and the quinone is regenerated and returned to the reaction.
The anthraquinone must be dissolved in a suitable solvent for the hydrogenation, oxidation and extraction steps - this is usually referred to as the working solution. The solvent is usually a mixture because quinones dissolve readily in non-polar aromatic solvents, such as alkylbenzene, whereas hydroquinones dissolve well in polar solvents, such as alcohols and esters. A variety of different mixtures are in use but the aim is to satisfy a number of criteria, namely good solubility of both quinone and hydroquinone, good stability in both hydrogenator and oxidiser, low solubility in water and aqueous hydrogen peroxide solutions, sufficiently higher or lower density than water to ensure separation of the two phases during extraction, low volatility, high distribution coefficient for hydrogen peroxide in the solvent-water system and low toxicity. 1
In the hydrogenator, the working solution is reacted with hydrogen in the presence of a catalyst. The process is exothermic and the heat of reaction is removed by cooling the working solution before it enters the hydrogenator, by cooling the reactor during hydrogenation and/or by cooling the hydrogenated working solution.
After the hydrogenation reaction, the working solution must pass through a filtration stage to remove all traces of catalyst. Even small traces of catalyst in the oxidation and extraction stages lead to significant losses of hydrogen peroxide and could present safety problems. During the oxidation stage, air is passed through the hydrogenated working solution to convert the dissolved hydroquinones to quinones and form the hydrogen peroxide. The air outlet is passed over activated carbon adsorbers to recover solvent.
Crude hydrogen peroxide is extracted from the oxidised working solution by treating with water. The working solution is then regenerated and fed back to the front of the process and the crude hydrogen peroxide (15-35 wt%) is fed to a treatment unit where the concentration is increased to 50-70 wt%.
Friday, February 1, 2008
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