A 4.98g sample of aniline (C6H5NH2, molar mass is 93.13g/mol) was combusted in a bomb calorimeter with a heat capacity of 4.25kJ/°C. If the temperature rose from 29.5°C to 69.8°C, determine the value of delta H°comb for aniline

the value of delta H° for aniline = - 3201. 5 Kj/mol

calculation

Step 1: find heat

Q (heat) = C (specific heat capacity) x ΔT (change in temperature)

C = 4.25 kj/c°

ΔT = 69.8-29.5 = 40.3 c°

Q = 4.25 kj/c x 40.3 c = 171.28 kj

Step 2: find the moles of aniline

moles = mass / molar mass

= 4.98 g / 93.13 g/mol = 0.0535 moles

Step 3 : find delta H

171.28 kj / 0.0535=3201.5 kj/mol

since the reaction is exothermic delta H = - 3201.5 Kj/mol