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Thursday, 6 August 2015

Bomb Calorimeter

Bomb Calorimeter Points : Bomb Calorimeter, experiment, Definition Bomb calorimeter are main components are bomb, bucket, stirrer, crucible or fuel pan, jacket, thermometer and so on. A identified amount of fuel under inquiry is kept in crucible. Crucible has a electric coil by d.c. supply in it. Bomb is charged by oxygen under pressure. Bomb is surrounded through a bucket contain water to soak up heat released as fuel burn. Bomb too has an outer jacket by dead air space surrounding bucket to minimise heat loss to surrounds. As electrical energy is fly into coil fuel gets ignite. Bomb is really a strong shell able of withstand on 100 atmosphere pressure. Inner bomb wall surface is lined by enamel and outside wall surface is plate so as to stop corrosion due to elevated temperature combustion products. Dissimilar operations as by it for calorific value measurement are as certain ahead. First weigh the unfilled calorimeter bucket and fill up it through a exact amount of water at temperature on 2–3°C less than jacket water hotness. Charge bomb by oxygen at high pressure with no troubling the fuel kept in crucible. Make sure that there is no leak in bomb and after ensure it as leak proof place it in bomb jacket. Put in thermometer and stirrer. Initiate stirrer for 3 to 4 minutes for temperature equality in bucket. Obtain temperature readings at exact interval, say after every five minutes.

Active the coil so as to fire fuel. Record temperature every 30 seconds awaiting utmost temperature is reach and after attain utmost temperature read temperature after every 5 minutes. These temperatures are necessary to description for the heat exchange by jacket water. Later on remove bomb as of calorimeter, release the gases and take apart the bomb. Collect and weigh iron fuse wire which remains. For getting precise effect the bomb should be washed by distilled water and washings titrated to get the quantity of nitric acid and sulphuric acid produced.

Amendment are prepared for small quantity of heat transfer which occur. For creation the calculations a curve of temperature is plot by time. Decide the charge of temperature rise before firing. Also, conclude the rate of temperature drop after the utmost temperature is reach. Cooling correction might be added to calculated temperature increase. Heat balance can be apply as, Heat released through fuel through combustion + Heat released with combustion of fuse wire = Heat absorbed through water and calorimeter.

For receiving heat absorbed through calorimeter the water equal of calorimeter is use which can be determined through burning a fuel of known calorific rate. Commonly benzoic acid and napthalene have calorific value of 6325 kcal/kg and 9688 kcal/kg are being use for finding water equal of calorimeter.

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