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katovenus [111]
3 years ago
9

One gram of liquid benzene is burned in a bomb calorimeter. The temperature before ignition was 20.826 ℃, and the temperature af

ter the combustion was 25.000 ℃. This was an adiabatic calorimeter. The heat capacity of the bomb,the water around it, and the contents of the bomb before the combustion was 10 000 J K-1 . Calculate for C6H6 (l) at 298.15 K from these data. Assume that the water produced in the combustion is in the liquid state and the carbon dioxide produced in the combustion is in the gas state.
Chemistry
1 answer:
gtnhenbr [62]3 years ago
4 0

Answer:fH = - 3,255.7 kJ/mol

Explanation:Because the bomb calorimeter is adiabatic (q =0), there'is no heat inside or outside it, so the heat flow from the combustion plus the heat flow of the system (bomb, water, and the contents) must be 0.

Qsystem + Qcombustion = 0

Qsystem = heat capacity*ΔT

10000*(25.000 - 20.826) + Qc = 0

Qcombustion = - 41,740 J = - 41.74 kJ

So, the enthaply of formation of benzene (fH) at 298.15 K (25.000 ºC) is the heat of the combustion, divided by the number of moles of it. The molar mass od benzene is: 6x12 g/mol of C + 6x1 g/mol of H = 78 g/mol, and:

n = mass/molar mass = 1/ 78

n = 0.01282 mol

fH = -41.74/0.01282

fH = - 3,255.7 kJ/mol

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 The heat that is needed  to raise the   temperature  of 78.4 g of aluminium from 19.4 °c to 98.6°c  is    5600.77 j

 <u><em>calculation</em></u>

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Given :

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