Energy Balances with Reaction: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

100 mol/h of N2 and 300 mol/h of H2 are fed to an isothermal reactor at 350°C to carry out the following gas-phase reaction:

N2 + 3H2 → 2NH3

Assume the heat capacities for the components are the following:

Cp(N2) = Cp(H2) = 29 J/mol-K

Cp(NH3) = 36 J/mol-K

How much heat must be removed from the reactor if the conversion is 75%? The heat of formation of ammonia at 25°C is -46 kJ/mol.

Example Problem 2

Consider the reaction of n-heptane to form toluene and hydrogen in a vapor-phase reactor. The fractional conversion of n-heptane is 0.7. The reaction requires 150 kW of heat to proceed. What is the outlet temperature? Assume negligible work and kinetic and potential energies.

image for an example problem in the Energy Balances with Reaction module on LearnChemE.com