Question

A quantity of 1.435g of naphthalene (C1oHs), a pungent-smelling substance used in moth repellents, was burned in a bomb calorimeter (constant volume). Consequently, the temperature of the water rose from 20.17°C to 25.84°C. If the mass of the water surrounding the calorimeter was exactly 2000g and the heat capacity of the bomb calorimeter was 1.80 KJ/°C, calculate the heat of combustion of naphthalene on a molar basis (molar heat of combustion), i.e. KJ/mol naphthalene. CH20 4.184 /g.°C

Answer 1

heat given off is q = mass x specific heat H2O x (Tfinal-Tinitial)
Calculate q (in J). Then
qtotal = qnaph + qcal
You know qtotal. You want qnaph. qcal = [1.80 kJ/C *(Tfinal-Tinitial)]. Change to J from kJ.
Solve for qnaph and that will be in J. Convert to kJ and that will be for 1.435 g, Convert to kJ/mol and you have it. Note C10Hs is a typo.