Calorimeter Heat Capacity & Vanillin Combustion Energy
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Calculate the heat capacity of a calorimeter through the combustion of benzoic acid and find the energy of combustion per gram and per mole of vanillin. Understand the calculations involved to determine these values accurately.
Calorimeter Heat Capacity & Vanillin Combustion Energy
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Presentation Transcript
Question 49 • The combustion of .1584g benzoic acid increases the temperature of a bomb calorimeter by 2.54°C.Calculate the heat capacity of this calorimeter. (The energy released by combustion of benzoic acid is 26.42 kJ/g.) A .2130-g sample of vanillin (C8H8O3) is then burned in the same calorimeter, and the temperature increases by 3.25°C. What is the energy of combustion per gram of vanillin? Per mole of vanillin?
To find the kJ of .1584g: 26.42kJ/g x .1584g = 4.18kJ/.1584g Next divide by the change in temp.: 4.18kJ / 2.54°C = 1.65kJ/°C Therefore, the heat capacity of the calorimeter is 1.65kJ/°C
Use the equation: ΔT x heat capacity of calorimeter = Energy released by reaction. 3.25°C x 1.65kJ/°C = 5.3625kJ Then divide by the number of grams to find kJ/g: 5.3625kJ/.2130g = 25.18kJ/g
Next multiply by the molar mass to find the kJ/mol: 25.18kJ/g x 152g/mol = 3830kJ/mol