An oxygen bomb calorimeter was used to measure the internal energy of combustion of sucrose, and then the standard enthalpy of formation of sucrose was determined from this. The formation of sucrose is:
12C_((S))+11H_(2(g))+11/2 O_(2(g))→C_12 H_22 O_(11(s))1
The combustion of sucrose reaction is:
C_12 H_22 O_(11(s))+12O_(2(g))→12CO_(2(g))+11H_2 O_((l))1
The reaction occurs at a constant volume, so the flow of heat corresponds to the internal energy change. The energy supplied as heat remains entirely within the system as solids have small molar volumes, so the molar enthalpy and molar internal energy are almost identical2, so this equates to the internal energy of combustion. The calorimeter was standardised using benzoic acid which has a known energy release on combustion, c = 26.434 kJ g-1 1. A known mass of benzoic acid is burned, and the heat capacity of the calorimeter is found using the equation:
C_cal=mc/ΔT 1
The internal energy change for sucrose can then be found using the same calorimeter constant:
ΔU= -C_cal ΔT1 Experimental
A 990 mg benzoic acid pellet was weighed and used to standardise the bomb calorimeter. The benzoic acid pellet was placed in bomb calorimeter, in contact with an ignition wire, and the bomb was pressurised with 25-30 atmospheres of oxygen gas. The …show more content…
The mean calorimeter constant, 10.3 ±0.0859 kJ K-1, was calculated from the temperature rise and the known mass of benzoic acid. The error in this value was found by standard deviation of the measurements through the mean average value. The error would be due to random error as there may be slight changes to the volume of water in the bomb calorimeter. Table 1 shows the individual runs of the benzoic acid with the heat capacity of the calorimeter being found for each one. The mean average was then determined from the individual
12C_((S))+11H_(2(g))+11/2 O_(2(g))→C_12 H_22 O_(11(s))1
The combustion of sucrose reaction is:
C_12 H_22 O_(11(s))+12O_(2(g))→12CO_(2(g))+11H_2 O_((l))1
The reaction occurs at a constant volume, so the flow of heat corresponds to the internal energy change. The energy supplied as heat remains entirely within the system as solids have small molar volumes, so the molar enthalpy and molar internal energy are almost identical2, so this equates to the internal energy of combustion. The calorimeter was standardised using benzoic acid which has a known energy release on combustion, c = 26.434 kJ g-1 1. A known mass of benzoic acid is burned, and the heat capacity of the calorimeter is found using the equation:
C_cal=mc/ΔT 1
The internal energy change for sucrose can then be found using the same calorimeter constant:
ΔU= -C_cal ΔT1 Experimental
A 990 mg benzoic acid pellet was weighed and used to standardise the bomb calorimeter. The benzoic acid pellet was placed in bomb calorimeter, in contact with an ignition wire, and the bomb was pressurised with 25-30 atmospheres of oxygen gas. The …show more content…
The mean calorimeter constant, 10.3 ±0.0859 kJ K-1, was calculated from the temperature rise and the known mass of benzoic acid. The error in this value was found by standard deviation of the measurements through the mean average value. The error would be due to random error as there may be slight changes to the volume of water in the bomb calorimeter. Table 1 shows the individual runs of the benzoic acid with the heat capacity of the calorimeter being found for each one. The mean average was then determined from the individual