Question

A 3.10 g sample of methane, CH4, is combusted in a calorimeter. The calorimeter and water combined have a heat capacity of 42.30 kJ/K. The observed temperature rise is 4.05 °C. Calculate the heat of combustion of methane in kJ/mol. The products of the reaction are water and carbon dioxide.

Answer 1

Answer – We are given, mass of methane = 3.10 g , change in temperature, Δt = 4.05^oC

Heat capacity, C = 42.30 kJ/K

We know the heat of this reaction

q = C * Δt

   = 42.30 kJ/K * 4.05 ^oC

   = 171.31 kJ

Now we need to calculate the moles of methane

Moles of methane = 3.10 g / 16.04 g.mol^-1

                              = 0.193 moles

So heat of combustion of methane = 171.3 kJ/0.193 mol

                                                         = 886.4 kJ/mol