REACTIONS: THERMODYNAMIC ASPECTS, KINETICS, AND CATALYSIS - Biomass as a Sustainable Energy Source for the Future - page 157

Materials needed : precision balance (0.01 g accuracy), beaker 250 mL, pipette
10 mL, H 2 O 2 solution (3.3% vol), KI saturated solution, and stopwatch.
How to do : Place the beaker on the precision scale with 100 mL H 2 O 2 and 2 mL
of KI solution. Shake a bit and start reading, every 15 s, the decrease in weight.
Repeat the experiment increasing the concentration of KI and plot the results
(the O 2 in mg as a function of time for the different KI concentrations).
P5.2 Give a Matlab formulation of the minimization of the Gibbs free energy for
calculating the equilibrium composition of Example 5.6.

1. Problem setup

Function main

R = 0.00198588; % kcal/mol//K
T = 1000; % K

% we store the species names in a cell array since they have different
% lengths (i.e. different number of characters in names) .
species = {'CH4' 'C2H4' 'C2H2' 'CO2' 'CO' 'O2' 'H2' 'H2O' 'C2H6'};

%
% $G_ˆ\ circ for each species . These are the heats of formation for each
% species
Gjo = [4. 61 28.249 40.604 -94.61 -47.942 0 0 -46.03 26.13]; % kcal/mol

2. Gibbs free energy of a mixture

function G = func (nj)
Enj = sum (nj ) ;
G = sum(nj.*(Gjo/R/T+log(nj/Enj)));

end

3. Linear equality constraints for atomic mass conservation

Aeq = [0 0 0 2 1 2 0 1 0
4 4 2 0 0 0 2 2 6

% oxygen balacne
% hydrogen balance
% carbon balance

1 2 2 1 1 0 0 0 2];

% the incoming feed was 4 mol H2O and 1 mol ethane
% moles of oxygen atoms coming in
% moles of bydrogen atoms coming in
% moles of oarbon atoms coming in

beq = [4
14
2];

4. Limits on mole number
No mole number can be negative, so we define a lower limit of zero for
each mole number.

LB = [0 0 0 0 0 0 0 0 0]; % no mole numbers less than zero