The heat capacity of a bomb calorimeter was determined by burning6.79 g of metha
ID: 675885 • Letter: T
Question
The heat capacity of a bomb calorimeter was determined by burning6.79 g of methane (energy of combustion = -802 kJ/molCH4) in the bomb. The temperature changed by10.8°C. (a) What is the heat capacity of thebomb?So, E=CT, so they say that the engergy of combustionis -802 kJ/mol CH4, we have 6.79 g, so we can do a quickcalculation to figure out that our energy is -340.35. T isgiven at 10.8 degrees C, so the heat capacity is simply-340.35/10.8 to get -31.5 kJ/degree C. However the answer ispositive 31.5 Now conceptually that makes sense, the heat capacity for aBOMB is not going to be negative. But on the calculations level,what is the problem that makes it negative? I suppose i'm supposedto use positive 340.35 kJ of energy, but why? Its an exothermicreaction, so it would make sense to exert energy, making itnegative. Anyway, any help would be greatly appreciated!!! (a) What is the heat capacity of thebomb?
So, E=CT, so they say that the engergy of combustionis -802 kJ/mol CH4, we have 6.79 g, so we can do a quickcalculation to figure out that our energy is -340.35. T isgiven at 10.8 degrees C, so the heat capacity is simply-340.35/10.8 to get -31.5 kJ/degree C. However the answer ispositive 31.5 Now conceptually that makes sense, the heat capacity for aBOMB is not going to be negative. But on the calculations level,what is the problem that makes it negative? I suppose i'm supposedto use positive 340.35 kJ of energy, but why? Its an exothermicreaction, so it would make sense to exert energy, making itnegative. Anyway, any help would be greatly appreciated!!!
Explanation / Answer
this is very simple. when ever you calculate heat in a bomb,you are calculating the energy or specific heat of anelement or compound (in this case CH4). but thequestion asks for the specific heat of the bomb, the equationis q(element or compound) =-q(bomb) same thing with specificheat.
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