When 0.514 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 25.8 0C to 29.4 0C. Find for the combustion of biphenyl in kJ/mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/0C.
Solution 73E: Step 1 of 3 A sample of biphenyl is combusted in a bomb calorimeter. Heat (q) is transferred to a system by absorption which causes a change in temperature (T) of the system. The change in temperature is directly proportional to the heat transferred. Therefore, heat absorbed by the system is given by: q T (Or) q = CT where’C’ is the proportionality constant known as heat capacity of the system. Step 2 of 3 Mass of biphenyl = 0.514 g T = final temperature of biphenyl = 29.4 C final Tinitialinitial temperature of biphenyl = 25.8 C The change in temperature, T = 29.4 C - 25.8 C = 3.6 C The heat capacity of the bomb calorimeter, C = 5.86 kJ/ C 0 Therefore, heat absorbed by the calorimeter is: q = CT