Question

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

Answer 1

 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