First determine the heat capacity of the calorimeter.
salicylic acid + O2 ==> CO2 + H2O (not balanced) + 21.90 kJ/gram; therefore
q = 21.90 x 0.1182g = ? kJ
q = heat capacity x delta T
Substitute q and delta T and solve for C (heat capacity) if the calorimeter.
E of combustion = mass sample x heat capacity x delta T. Solve for E combustion and that is 0.2086g sample. Convert to 1 gram of the sample. Watch the units.
The complete combustion of salicylic acid releases 21.90 kJ of energy per gram of salicylic acid. In a particular bomb calorimeter (initially at room temperature), the combustion of 0.1182 g of salicylic acid, in the presence of excess oxygen, causes the temperature of the calorimeter to rise by 2.84 °C. When a 0.2086-g sample of an unknown organic substance is similarly burned in the same calorimeter, the temperature rises by 3.50 °C. What is the energy of combustion per unit mass of the unknown substance?
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