heat sample A bomb calorimeter, or a constant volume calorimeter, is a device of
ID: 304425 • Letter: H
Question
heat sample A bomb calorimeter, or a constant volume calorimeter, is a device often used to determine the heat of combustion of fue ls and the energy content of foods In an experiment, a 0.5444 g sample of quinizarin (C14HgO4) is burned completely in a bomb calorimeter. The calorimeter is surrounded by 1.169x10 g of water. During the combustion the temperature increases from 28.51 to 30.99 °C. The heat capacity of water is 4.1841 g.??" The heat capacity of the calorimeter was determined in a previous experiment to be 892.2 J/°C. Assuming that no energy is lost to the surroundings, calculate the molar heat of combustion of quinizarin based on these data. Water C14HgO4(s) + 1402(8)>4H20() + 14 Co2(g) + Energy Insulated Sample ng dish Burning Steel sample Molar Heat of Combustion- kJ/mol outside chamber bomb Combustion (bomb) calorimeterExplanation / Answer
Heat absorbed by water = specific heat of water x mass of water x temp change
= 4.184 J/gC x 1.169 x 10^ 3 g x ( 30.99-28.51) C
= 12130 J = 12.13 KJ
Heat absorbed by calorimeter = Heat capacity of calorimeter x temp change
= 892.2 J/C x ( 30.99-28.51) C
= 2213 J = 2.213 KJ
Total heat absorbed by water and calorimeter = 12.13 + 2.213 = 14.343 KJ
This heat was released by reaction
hence heat of combustion = 14.343 KJ
Moles of compound combustion = mass of compound / molar mass of compound
= 0.5444 g / ( 240g/mol) = 0.00227 mol
Now heat of combustion in KJ/mol = ( 14.343 KJ / 0.00227 mol) = - 6319 KJ/mol
( -ve sign indicates heat is released)
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