Midterm_Exam-CHEM4005-2010-2011(1)

MID SEMESTER EXAMINATION Faculty of Engineering COURSE CODE

:

CHEM4005

LEVEL / SEMESTER

:

4/1

COURSE TITLE

:

Reaction Engineering

ACADEMIC YEAR

:

2010-2011

DATE

:

Monday, 06 December 2010

TIME

:

09:00

DURATION

:

2 Hours

MAXIMUM MARK

:

100

COURSE COORDINATOR :

Ahmed J. Ali Al-Dallal

STUDENT NAME STUDENT ID

GROUP NO

INSTRUCTIONS TO CANDIDATES This question paper consists of 3 pages only. • Answer ALL questions. • Write your ID, NAME and GROUP NUMBER clearly on all of your answer books. • Follow all examination rules. • Do not bring books or other related materials into the examination room. •

Page |2

Question 1:

[40 marks]

The following elementary, reversible, gas-phase reaction takes place in a continuous stirred-tank reactor (CSTR): A + B  C The following information are known: - Forward reaction constant (kf ) = 0.5 L/mol.s @ 50oC - Equilibrium constant based on concentration (Kc) = 1.2 L/mol @ 50oC - Total inlet flowrate is 10 L/min, with initial concentrations of C = 1M & C = 2M. - The reactor is maintained under isothermal conditions at 50oC and at 1 atm. i) Complete the following Stoichiometric Table Q1 for this reaction (fill in shaded areas): AO

BO

Table Q1: Stoichiometric Table

ii) Write each species concentration in terms of conversion, XA. iii) Solve for the equilibrium conversion at 500C. iv)What CSTR volume is required to achieve 80% of the equilibrium conversion?

Question 2:

[30 marks]

Pure gaseous (A) at about 3 atm and 30°C, with initial concentration CA0=120 mmole/liter, is fed into a 1 liter CSTR at various flow rates. Reactant (A) decomposes in the reactor and the exit concentration of A (CA) is measured for each flow rate (v0). The flow rate and concentration data are given in Table Q2. The reaction is: A  3P Table Q2: Flow rate and concentration data v0 (Liter/min) 0.06 0.48 1.5 8.1 CA (mmole /Liter) 30 60 80 105 i) Write the mole balance for the CSTR where a 2nd order reaction is taking place. ii) Show how you will plot the above data to obtain a straight line, and thus determine the reaction rate constant (k).

Question 3:

[30 marks]

The homogeneous gas decomposition of phosphine, 4 PH3(g) → P4(g) +6 H2(g), proceeds at 649°C (rate constant = 10 hr-1) in a plug flow reactor operating at 649°C and 460 kPa which produce 80% conversion of a pure feed consisting of 40 mol/hr of pure phosphine. i) Write the mole balance, rate law and stoichiometry equations for the system. ii) Combine the three equations in (a). iii) Estimate the volume of reactor. Additional Data R (Gas Constant) = 0.0821 atm.L/mol. K

Page |3 = 8.314 Pa.m3/ mol. K

STUDENT NAME STUDENT ID

GROUP NO

Graph Paper for Q2