Explain, giving examples from the articles Essay Example for Free

Explain, giving examples from the articles Essay Explain, giving examples from the articles, what is meant by oxidation and show how oxidation reactions are used to cause explosions. Outline reasons why some explosive mixtures oxidise faster than others. [4] An element is oxidised if It gains oxygen. It loses electrons. Its oxidation state increases. Explosives such as gunpowder or black powder contain powdered carbon, sulphur and potassium nitrate. This can be ignited by a fuse where carbon and sulphur will be oxidised. Carbon will form into Carbon Dioxide and Sulphur will form into Sulphur Dioxide. This reaction shows when a pure sample of carbon burns in air. C(s) + O2(g) i CO2(g) This is an oxidation reaction where carbon has gained oxygen and its oxidation state has increased from 0 to +4 The potassium nitrate in the gunpowder acts as an oxidiser and provides oxygen for the reaction. All the oxygen required is available almost instantly; therefore carbon and sulphur burn in a fraction of a second. The reactants and products of this reaction are Reactants: KNO3(s) C(s) S(s) Products: CO2(g) SO2(g) N2(g) + Other solid products The volume of the reactants is very small. The products are mainly hot gases produced suddenly in a confined area. This rapid increase in pressure leads to an explosion. (132 Words) To maximise the force of the reaction, all solids involved are finely divided into powders and the proportions of reactants in the mixture are calculated very accurately. The power of the explosion is made greater by confining the reaction inside a restricted space e. g. Cannon. Fuels used in fireworks; Potassium Chloride (KClO3) and rockets; Hydrogen Peroxide (H2O2) are mixed with oxidisers to produce explosions. Some explosive mixtures oxidise faster than others if the reacting element(s) gains more oxygen and has a greater oxidation state.   Give an account of the development of chemical compounds for use in explosives. Describe the advantages of each new chemical explosive over its predecessors, and describe how the explosives were adapted to make them safer and more effective. [9] The very first discovery of an explosive chemical compound was unintended. In 1846 Dr Christian Schi nobein accidentally spilled concentrated sulphuric and nitric acids; he quickly cleaned the contaminated area with an apron made of cotton. Knowing that the apron would soon be destroyed by the acids, he rinsed it out with water and hung it up to dry in front of the fire. Moments later the cloth burst into flames. Dr Schi nobein was not aware that he had discovered gun cotton otherwise known as Cellulose Nitrate or Nitrocellulose. From 1860s onwards the military began investigating the possibilities of cellulose nitrate as a smoke-free gunpowder. Towards the end of the nineteenth century, black powder had been replaced as a propellant for military purposes by a smokeless powder based on cellulose nitrate. This substance catches fire very quickly and burns without lighting a fuse; produces very little smoke and creates an impulsive impact. Therefore, explosive shells were replaced by cannon balls and bullets replaced musket balls. This smokeless powder used by the British Army is called cordite and was invented in 1880s. It consists of Cellulose Trinitrate and Glycerol Trinitrate amongst other substances. This substance catches fire very easily and burns quickly. The powder was transformed into a jelly-like substance by adding an organic solvent propanone. This smokeless powder is now used worldwide as a military propellant. (253 Words) In 1847 an Italian scientist, Ascanio Sobrero was experimenting with concentrated acids. He combined together nitric, sulphuric acids with glycerine. The new substance formed was a yellowish oil. He had discovered Nitroglycerine. He experimented with a small sample and realised that was extremely unstable. Its behaviour was unpredictable. It could be detonated by the touch of a feather. Immanuel Nobel and his son Alfred Nobel from Sweden were responsible for controlling Nitroglycerine. Nobel made a deliberate explosion by mixing Nitroglycerine with (kieselguhr) which is a silica based mineral. He made a paste which could be shaped into rods. These would only explode when they are intentionally detonated. These are the very first safe high explosives. Nobel developed even safer ways to detonate these explosives. He found out that the most reliable and effective way to set off nitroglycerine was to use small quantities of gunpowder. He also invented the first percussion cap that gives out a small explosion when it is given a sharp impact. The caps were filled with a compound known as fulminate of mercury Hg(CNO)2. This substance is very sensitive that even a finger tap can cause it to detonate. This ignites the gunpowder or other explosives. In 1867 Nobel patented his dynamite. It was called Dynamite No 1. He soon realised that very effective mixtures could be made by replacing the inert kieselguhr by a substance that would itself burn or explode. He combined nitroglycerine with charcoal, barium nitrate and sulphur which led a new explosive product in 1869. It was called Dynamite No 2. This product was suitable for use in quarries and coal mines. Nobel patented another explosive product in 1875. He added 7 to 8 per cent of collodion (nitrated cellulose) to warm nitroglycerine forming a stiff jelly-like substance known as blasting gelatine. This product proved to be more powerful explosive than dynamite, because both nitroglycerine and collodion were explosive. During the Second World War, Trinitrotoluene (TNT) was developed. TNT contains nitro groups (NO2). It doesnt react with metals therefore can be used in metal containers to produce bombs. TNT causes headaches, anaemia and skin irritation. Subsequently, workers in factories often suffered health problems. (280 Words)   Discuss, with reference to high and low explosives, the ideal features of an explosive reaction, explaining, with examples, how chemical reactions produce energy and how they cause increase in pressure. [6] Nitroglycerine is acknowledged as a high explosive. It produces a large volume of hot gas. Its decomposition only takes microseconds at a pressure of 275 000 atmospheres. Black Powder and Cellulose Nitrate are considered as low explosives. They produce a large volume of hot gas. The decomposition takes millisecond at a pressure of 6000 atmospheres. An ideal explosive reaction must take place very quickly. It must be an exothermic reaction where heat is given out. The products formed must mainly be hot gases produced in a confined space. This leads to a big rise in pressure which is the main cause of the explosion. An equation for explosion of nitroglycerine C3H5N3O9 (l) 3CO2 (g) + 21/2H2O (g) +11/2N2 (g) + 1/4O2(g) 1 mol of liquid 7. 25 moles of gas No oxygen supply from air was needed for the reaction. The exact products are based on the actual explosion. In an oxidation reaction oxides of nitrogen such as (NO and NO2) may be produced. The amount of heat energy released from a nitroglycerine explosion is 6275 KJ kgi 1. The increase in pressure will produce greater energy from the explosion. Describe how UK methods of manufacture of propanone have changed since the beginning of the First World War. [3] Before the war propanone was manufactured by dry distillation of wood in a process that excluded air. This method was very inefficient. In 1914 a Russian chemist, Chaim Weizmann, developed a new process that produced propane by bacterial fermentation of starch in maize. This process was capable of producing 30 000 tonne. After the war propanone was manufactured from propan-2-ol by passing the vapour over a copper catalyst at 500i C and 400kPa. Propanone was produced from propene, a product of catalytic cracking of crude oil fractions. (230 Words)   Discuss how attitudes to health and safety in chemical research and industrial chemistry have changed over time. Use examples from the history of development and manufactures of explosives and medicines. [4] The discovery of cellulose nitrate was a hazard of health and safety. The discovery of nitroglycerine was another major hazard as it its behaviour was very unpredictable. Its discoverer Ascanio Sobrero was badly scarred as a result of an unexpected explosion that spattered glass fragments into his hands and face. He said victims killed during nitroglycerine explosions He was ashamed to be the inventor of such a deadly explosive. In Nobels nitroglycerine factory, there was an explosion that killed his young brother Emil and another chemist. However test on animals showed that nitroglycerine causes blood vessels of the brain and heart to flow with blood. Nitroglycerine was considered a possible treatment. Nitroglycerine is effective for treating angina pectoris; intense pain in heart. A medicine known as amyl nitrate similar to nitroglycerine are used as treatments to this day. (110 Words) OCR-AS Chemistry (Salters) Open-Book Paper (2005) 2852/01 1 Name: Mohammad Ahmed Candidate No. 9023 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.

Michelangelo Essay -- essays research papers

Michelangelo Buonarroti is arguably one of the most inspired creators in the history of art and the most potent force in the Italian High Renaissance. As a sculptor, architect, painter, and poet, he exerted a tremendous influence on his contemporaries and on subsequent Western art in general. Michelangelo was born March 6, 1475, in the small village of Caprese near Arezzo. He lived during the Italian High Renaissance. Although he was born in Caprese, he lived in Florentine. There he created some of the most spectacular works of art ever. One in particular was the statue David. Michelangelo had a serious reason for creating this statue. He made this statue to show the people who David, the Old Testament hero who defeated Goliath, actually was. David is shown by Michelangelo as a lithe nude youth, muscular and alert, looking off into the distance as if sizing up the enemy Goliath. The fiery intensity of David’s facial expression is termed terribilità  , a feature characteristic of many of Michelangelo’s figures and of his own personality. David, Michelangelo’s most famous sculpture, became the symbol of Florence and originally was place in the Piazza della Signoria in front of the Palazzo Vecchio, the Florentine town hall. With this statue, Michelangelo proved to his contemporaries that he not only surpassed all modern artists, but also the Greeks and Romans, by infusing formal beauty with powerful expressiveness and meaning. Michelangelo’s David does not make me feel a...

Sci228 Ilab

Carmen Coronado iLab SCI 228 June 12, 2011 BMI Part 1 Define BMI-You must define BMI and not just as a general definition indicating its relationship to height and weight. Please also do not forget to define the actual term BMI! The body mass index (BMI) is of a measurement that was introduced in the early 19th century in order to categorize the entire population’s weight problems. The BMI is a statistic that is used to classify people's weight as underweight, normal weight, overweight or obese. The formula that is used to calculate ones BMI is that the metric system will divide ones weight in kilograms by ones height in squared meters. Then the units call for the physicians to multiply ones weight in pounds by 703 and will then divide the number that was gotten by ones height in inches squared. The body mass index will indicate if one is underweight, normal, overweight, and or obese categories. Part 2 Calculate BMI-Many students use an automated calculator to complete this part of the assignment. I will deduct points if I do not see the actual math calculations. Please include all stages of the math calculations associated with determining your BMI. There is an approximately 1800 calories that should be ingested. As to my BMR (basal metabolic rate) is about 1300 calories, which I should be eating around 700 more calories in order for it to account for the amount of energy I will be expending during the day in both my daily activities. With regards to food, this entails eating adequate portions of carbohydrates, proteins, and fats. A bowl of steel-cut oats with added whole milk, with a handful of almonds, topped with a tablespoon of ground flaxseed and mixed berries equates to around 600 calories. In the mid-morning I would have a snack of a protein shake and an apple that will work out to be about 100 calories. For lunch a tossed salad containing grilled chicken pieces, romaine lettuce, corn, shoestring beets, carrots, soybeans that will work out to be about 500 calories. For dinner I would have a plate with fried rice, some mixed vegetables, mashed potatoes, and a piece of fish seasoned with garlic salt and lemon that would come out to be about 500 calories. So I would be left with 100 calories at the end of my day. Reference -Janiszewski, Peter. Body mass index (BMI) as a measure of obesity and health: a critical appraisal. June 12, 2011. http://scienceblogs. com/obesitypanacea/2010/03/body_mass_index_bmi_as_a_measu. php

The Success Of A Circle Time - 872 Words

Successful Circle Time Circle time is one of the most fun and creative times of the school day. Preschool children, typically ages three to around six, are very hands one and mobile. They want to move about and explore things around them. For any teacher struggling with circle time and keeping the attention of their students I would suggest multiple tips on how to keep students engaged. One is to make circle time interactive and get the students involved in the circle time. An example would be giving each student a part in a song or a story to act out. Another suggestion would be to start each circle time with a song and dance so that students can release some of the energy that they have and be ready to focus during circle time. It is also a great idea to have students move around during circle time so they are not getting restless and moving in anyway they want (). Two very key things for circle time to be a success is to be consistent with circle time and have it daily so that stu dents know what to expect. I have observed activities like reviewing the calendar, weather, and reading a short book. Finally, one must be aware and patient of the disturbances that will pop up during circle time. Know that students are all developing in different ways and not one is like the other. While one student may sit attentively for a prolonged period of time, another may not be at that point yet. Plan circle time around your students needs and it will be a very happy experience forShow MoreRelatedThe Field Of Business Administration Essay1360 Words   |  6 Pagesexecute any given plan is subjective, yet crucial. Starting up your own company takes patience and time; however, a number of entrepreneurs tend to take out huge loans in an attempt to build a flashy-looking business with no business plan whatsoever. 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