Question

The number of litres of air required to burn 8 litres of C2H2 is approximately?

Answer 1

We need a stoichiometric equation, ...................and get an approx. volume of `100*L` air.........

Explanation:

We need a stoichiometric equation to represent the combustion:

`HC-=CH(g) + 5/2O_2(g) rarr2CO_2(g) +H_2O(l)`

And thus given that at constant pressure, and constant temperature (conditions that must be reasonably assumed!), one volume of acetylene gas requires `5/2` volumes of dioxygen for complete combustion..........

And so, if there are `8*L` of acetylene, we requires a volume of `8*Lxx5/2=??L` dioxygen gas.........

But we are not finished there (says he, finally reading the question!). The percentage of oxygen in air BY volume, is approx. `21%`.

And thus we need a volume of ....

`(20*L*O_2)/(0.21*L*O_2*L^-1*"air")~=100*L*"air"`.........