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Question:When the heat capacity is in the form J/gK why is the temperature used in celsius not kelvin as seen in http://answers.yahoo.com/question/index;_ylt=AilETqR21jKt4lRe.9N0naIjzKIX;_ylv=3?qid=20081023052422AAFfQ2V
shouldnt you convert your 12.5 degrees celsius to kelvin so the units will cancel? thanks for your help..how do i choose best answer =/ wana give those that helped credit =)
Answers:im sick of doing your homework
you do it
Question:I have heard of a calorimeter. Apparently it is an instrument used to measure calorie content. How does one work? Can you just go buy one of these things? What about when the news goes to check out diet restaurants to see if the food has the calories that the restaurant claims it does, what do they use?
Answers:Ok, here is the gobbledeegook science stuff. No you cannot do it at home unless you are a physicist!
Physicists measure the energy content of food by burning the food. To a physicist, a calorie is the heat flow needed to raise the temperature of one gram of water by one degree Celsius. To measure the calorie content of food accurately, scientists use a bomb calorimeter . The food sample to be measured is dried and ground into a powder (important point all water content eliminated). Then it is placed into the bomb calorimeter, a strong metal container surrounded by a water bath. The metal container is pumped full of pure oxygen at 30 atmospheres pressure and the food is ignited. The resulting energy release is fast and violent, just like a bomb. The steel container holds in the explosion. Pure oxygen promotes combustion, and high-pressure oxygen greatly enhances combustion. All of the burnable parts of the dried and powdered food will burn in a calorimeter, leaving just a touch of ash. The calorimeter turns the energy stored in the food into heat flow. The temperature increase of the water and metal of the calorimeter reveals how many calories the food contained.
Answers:The fact that enthalpy is a state function means that the enthalpy of a chemical system does not depend on the details of how that system came to be. If you determine the enthalpy change for a particular reaction (say, by calorimetry), that number doesn't depend at all on how exactly the reaction took place. This leads to Hess' Law, which says that you can calculate the enthalpy change for any reaction as the sum of enthalpy changes for any arbitrary chain of intermediate reactions (just as long as you start with the same reactants and end with the same products). The consequence of this is that you can calculate enthalpy changes for reactions that have never even been measured by calorimetry, if you can come up with some chain of reactions for which the enthalpy changes are known that lead to the same products.
Question:added to 135 mL of a 1.00 M potassium sulphate solution. The total heat capacity of the calorimeter including all the contents was 1.75 kJ oC-1. The temperature in the calorimeter rose from 24.50oC to 28.70 oC.
Calculate the enthalpy change, in kJ, for the reaction:
Me2+ (aq) + SO42- (aq) = MeSO4 (s).
Me is the alkaline earth metal in question.
Answers:135 mL of 1.00 M MeCl2 = 0.135 mol MeCl2
135 mL of 1.00 M K2SO4 = 0.135 mol K2SO4
So the chemicals may fully react to form 0.135 mol MeSO4:
Me(2+)(aq) + SO4(2-)(aq) = MeSO4 (s).
Heat generated = (28.70 C - 24.50 C)*1.75kJ/ C = 7.35 kJ.
Hence the enthalpy change = 7.35 kJ/0.135 mol = 54.4 kJ/mol.
Footage of Times Square Bomb Test :In the video released by the FBI, the Operational Technology Division sets up tests in a field in Osceola Mills, Pennsylvania, on June 29. The explosive tests involve a 1993 Nissan Pathfinder stuffed with 250 pounds of ammonium nitrate and diesel fuel, along with three 25-pound propane tanks and two five-gallon gasoline containers. These are the same materials allegedly found in the Times Square car bomb. Taken from various angles, using normal and slow-motion cameras, the FBI video reveals that the explosion would have been quite large -- almost certainly enough to kill scores of people in crowded Times Square. In a memorandum urging a federal judge to sentence Shahzad to life in prison, prosecutors today said Shahzad told the FBI that -- had the Times Square bomb been successful -- he planned to build and set off another car bomb somewhere in New York City two weeks later. 'While it is impossible to calculate precisely the impact of Shahzad's bomb had it detonated, the controlled detonation... demonstrated that those effects would be devastating to the surrounding area,' the sentencing document said.
GBU-39 Small Diameter Bomb SDB :Two variants are being developed. One version of the SDB is equipped with a GPS-aided inertial navigation system to attack fixed/stationary targets such as fuel depots, bunkers etc. The second variant (GBU-40) includes a thermal seeker with automatic target recognition features for striking mobile targets such as tanks, vehicles, and mobile command posts. The GBU-39 has a circular error probable (CEP) of only 5-8 meters, which means it has a 50% probability of hitting within 5-8 meters its intended target, which should minimize collateral damage. CEP is reduced by updating differential GPS offsets prior to weapon release. These offsets are calculated using an SDB Accuracy Support Infrastructure, consisting of three or more GPS receivers at fixed locations transmitting calculated location to a correlation station at the Theater Combined Air Operations Center. The corrections are then transmitted by Link 16 to SDB-equipped aircraft. The small size of the bomb allows a single strike aircraft to carry more of the munitions than is possible utilizing currently available bomb units. The SDB carries approximately 38 lb (17 kg) of AFX-757 high explosive, yet because of its design it has the same penetration capabilities as the 2000 lb BLU-109. During demonstrations, the SDB has successfully penetrated more than 8 ft (2.4 m) thick reinforced concrete. It also has integrated "DiamondBack" type wings which deploy after release, increasing the glide time and ...