2.00 g of Benzoic Acid are burned in a bomb calorimeter, and the temperature inc

Question

2.00 g of Benzoic Acid are burned in a bomb calorimeter, and the temperature increase from 17.84 degrees C to 23.34 degrees C.

a) What is the heat capacity of the calorimeter?

b) After conduction the next experiment (which will be described in part c), you realize that for determining the heat capacity of the calorimeter, 1 L of water was used whereas for the experiment in part c, 2 L of water were used. In order to avoid habing to redo the experiment, calculate the heat capacity of the calorimeter containing 2 L of water.

c) You burn 4.08 g of Arginine in the bomb calorimeter (with 2 L of water as described in part b). The temperature increases from 17.49 degrees C to 23.83 degrees C. Determine the enthaply of combustion and the enthalpy of formation of Arginine.

d) Arginine has a standard molar entropy of 250.6 J/molK. Determine the entropy of reaction for the combustion of 4.08 g Arginine.

e) Calculate the entropy change of the surroundings and the universe for the combustion of 4.08 g of Arginine.

f) Calculate the Gibbs energy of reaction fro the combustion of 4.08 g of Arginine.

g.) Predict the enthalpy of combustion for 4.08 g of Arginine at 373 K. Arginine has a heat capacity of 232.8 J/molK which you may assume is constant.

Explanation / Answer

a) 2.00 g benzoic acid
heat of formation for benzoic acid = 26.435 kJ/g
therefore,
26.435kJ/g x 2.00g = 52.87kJ is relased upon benzoic acid combustion.
heat absorbed by calorimeter = heat released upon combustion of benzoic acid.
52.87kJ
heat = heat capacity of the calorimeter x deltaT (difference in temerature)
52.87kJ = heat capacity x 5.5 C
9.61 kJ/C = heat capacity of the calorimeter

b) C = ms

you doubled the mass (m) so just double the heat capacity

9.61 kJ/C X 2 = 19.22 kJ/C

c) Heat(enthaply) of Combustion:

[Heat capacity * deltaT (difference in temerature)] divided by the mass of the sample
Note: use the heat capacity of part b
so: (19.22 kJ/C * 5.5 C) / 4.08 g = 26 kJ/g

For the Heat (enthalpy) of formation I need more information or it could be -26 but i highly doubt that.

and thats all i can do right now but if i come up with something i'll come back to complete it.

sorry...

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