When 0.7521 g of benzoic acid was burned in a calorimeter containing 1000 g of water, a temperature increase of 3.60 ℃ was observed. What is the heat capacity of the bomb calorimeter, excluding water? The heat of combustion of benzoic acid is -26.42 kJ/g.

The correct answer is 1335.4 J/ °C.

Explanation:

Based on the given information, the amount of benzoic acid burned is 0.7521 grams, the amount of water present within a calorimeter is 1000 grams and there is an elevation in temperature of 3.60 °C. The heat of combustion of benzoic acid given is -26.42 kJ per mole.  

Now the amount of heat discharged in a reaction is:  

= 0.7521 grams × -26.42 kJ / gram = -19.872 kJ or -19870 J

qreaction = - (qwater + qcal)

-19870 J = - (mwatersΔT + CcalΔT

= - [(1000 grams × 4.184 J/g degree C × 3.60 degree C) + (Ccal 3.60 °C)] (The specific heat of water is 4.184 J/gram °C)

(1000 gram × 4.184 J/g °C × 3.60 °C) + (Ccal 3.60 °C) = 19870 J

15062 J + Ccal 3.60 °C = 19870 J

Ccal 3.60 °C = 4807.6 J

Ccal = 4807.6 J / 3.60 °C = 1335.4 J/°C or 1.3 kJ/°C.  

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