Stoichiometric Combustion Calculator for Alkane, Alkene and Alkyne fuels.

• I am going to write a program which will save the plot generated using MATLAB for comparing the effect of a number of moles of carbon on stoichiometric coefficient (ar). I will also describe how does this trend change with the fuel type (alkanes, alkenes, alkynes) by looking at the plot generated.

Below is the balanced chemical equation for the complete combustion of a general hydrocarbon fuel `C_aH_b`

`C_aH_b + (a +b/4)O_2 rarr aCO_2 + b/2H_2O`

where stoichiometric coefficient 'ar' = a + b/4 and number of moles of carbon 'n' = a according to the challenge.

Thus, the formula for ar in terms of n for an alkane, alkene, and alkyne fuel respectively is `ar = 1/2(3n + 1)`, `ar = 3/2n`, and `ar = 1/2(3n - 1)`.

• How does the coding in MATLAB look like?

Code:

%Program to generate stoichiometry combustion calculator
clear all
close all
clc

%Ten consecutive number of moles of carbon (from 2 to 11)
n = 2:11;


%Relation between Stoichiometric co-efficient (ar) and number of moles of carbon (n) 
%From the formulas posted above,

% ar for alkanes = 1/2*(3n + 1), using n for alkanes as it starts from 1 (CH4)
alkane_ar = 0.5*(3.*n+ 1);  

% ar for alkenes = 3/2*(n),
alkene_ar = 1.5.*(n);  

% ar for alkynes = 1/2*(3n - 1)
alkyne_ar = 0.5*(3.*(n) -1);  
          
%plotting the above data
figure(1) 
plot(n,alkane_ar,'-rd','markerfacecolor','y','linewidth',2)
hold on
plot(n,alkene_ar,'-bs','markerfacecolor','m','linewidth',2)
plot(n,alkyne_ar,'-ko','markerfacecolor','g','linewidth',2)
title('Comparing the effect of number of moles of carbon on the stoichiometric co-efficient')
xlabel('Number of moles of carbon')
ylabel('Stoichiometric co-efficient')
legend('Alkane','Alkene','Alkyne','Location','southeast');
grid minor
axis([0 12 0 20])

%saving the plot generated in figure 1 as comparing_plots
saveas(gca,'Comparing_plots.png')

Note: I have used ten consecutive number of moles of carbon (from 2 to 11) for an alkane, alkene, and alkyne fuel type as there was no specific domain provided in the challenge interface. As alkane starts from 1 mol of carbon i.e from `CH_4` and alkene and alkyne starts with 2 moles of carbon i.e from `C_2H_4` and `C_2H_2` respectively, while generating the plot there won't be any stoichiometric coefficient at 1 mol of carbon for alkene and alkyne. Thus, to avoid this confusion in any general readers mind I chose that particular domain.

• How does the 'Comparing_plots.png' file look like?

Comparing_plots.png file:

Result:
From the above plot, we can see that the rate of increase of stoichiometric coefficient with respect to the number of moles of carbon is same for all of the fuel type (alkane, alkene, alkyne) i.e `3/2` but for a particular number of mole of a carbon, the respective alkane will have the highest stoichiometric coefficient followed by the respective alkene and alkyne. To be specific at any given value of n, ar for alkane will be 1 + ar of alkyne and ar for alkene will be 0.5 + ar of alkyne.