Problem Definition: In this we have to compute the stoichiometric coefficients(ar) of alkanes, alkenes and alkynes and build a relationship with number of moles of atoms. And also showing it graphically.
Procedure: First we need to build a relationship between ar and n by comparing number of moles on left and right hand sides for alkanes, alkenes and alkynes. Subsequently we will use different values of n and try solving the value of ar based on the relationship derived.
Theory: The combustion reaction of hydrocarbon is
CxHy +(x + y/4)O2 --> (x)CO2 + (y/2)H2O
For Alkane x = n, y = 2n+2 For Alkene x = n, y = 2n For Alkyne x = n, y = 2n-2
Substituting these in above reaction we get
For Alkane ar = (3n+1)/2
For Alkene ar = (3n)/2
For Alkyne ar = (3n-1)/2
Result: As we can see from the graph that for a particular no. of Carbon atoms the ar value of alkane is higher than that of alkene and alkyne. Thus, we need to have more no. of moles of oxygen for alkanes than alkenes and alkynes
