PROBLEM 5.58 CALORIMETRY

1
PROBLEM 5.58 CALORIMETRY

• You are given a mass of benzoic acid and its heat
  of combustion. From that get the q ( which is
  also the ?H). Then use the ?T to calculate C
  (heat capacity of the calorimeter). REMEMBER in
  a bomb calorimeter you do not show the mass of
  the water as it never changes for the same
  calorimeter device, Bubbies.
• 1.640 g HC2H5O2 x -26.38kJ - 43.2632
  kJ (for this 1.640 g sample) q
  
• 1 g
  
  

All combustions are exothermic, have a negative
sign for q
qreaction -CBOMB calorimeter?T
The heat lost by combustion of benzoic acid (-
?H) is the heat gained by the calorimeter.
- 43.2632 kJ -CBOMB (27.20-22.25)
- 43.2632 kJ -CBOMB (4.95 CO)
2
PROBLEM 5.58 CALORIMETRY (continued)

• B) Use the heat capacity calculated in part A)
  and the data from the organic sample to calculate
  q. Note it is the same calorimeter and the same
  heat capacity.

- 8.74004 kJ / Co - CBOMB
Rounded to three significant figures, this is the
heat capacity of the calorimeter for the other
parts of this problem.
8.74 kJ / Co CBOMB
The answer must be in kJ per g, so 40.9032kJ
x x 30.98731.0kJ/g 1.320g 1g

qreaction -CBOMB calorimeter?T
qreaction 8.74 kJ / Co (4.68) 40.9032kJ for
1.320g