Midterm Examination

 

Date: November 2nd, 1998

Permitted Aids: TI30X calculator, Study Sheet (one sided)

Answer all questions and show all work. Hand in study sheet with this exam.

 

Question 1

A catalytic, gas phase reaction

takes place in an isothermal plug flow reactor. The reactants enter as a stoichiometirc mix, together with an inert species at 55 oC and 5 atm. The mole fraction of the inert in the feed is 0.4

  1. What are the concentrations of A, B, C, and I assuming isobaric operation and a fractional conversion of species A of 0.6?

  2. The specific reaction rate at the operating temperature, written in terms of the consumption of species B, is

Neglecting pressure drop, how much catalyst is needed to convert 10% of the reactants to products?

  1. It turns out that
for this reactor equals 0.01. Taking into account pressure effects, how much catalyst is needed to achieve 10% conversion?

Click here for the solution.

 

 

Question 2

The elementary reaction

takes place in the gas phase of a square duct. The feed to the duct consists of a gas stream of pure A and a liquid stream of pure B. The flowing liquid B covers the bottom of the duct and evaporates into the gas phase, maintaining its equilibrium pressure throughout the system. The gas phase, meanwhile, occurs as a plug flow. The volume of the liquid B is negligible relative to the gas phase.

  1. Express the rate law as a function of conversion, evaluating numerically all possible symbols. (Note the units of k.)
  2. What is the reaction rate,
, when the conversion is 50%?

Additional Data

P0 1 atm

k 106 ft3/lbmol•s

T 540 oF

Pv,B 0.25 atm at 540 oF

FA0 1.5 lbmol/s

Click here for the solution.

Other Useful Information for the Exam

R=0.082 (litre•atm)/(mol•K)=0.73 (ft3•atm)/(lbmol•oR)=8.309 (kPa•litre/mol•K)

oR=oF+459.69 K=oC+273.16