Question

Combustion of which gas gives 7 moles of gaseous product from 6 moles of gaseous reactant?

`1.` `CH_4;`
`2.` `H_2C=CH_2;`
`3.` `HC-=CH;`
`4.` `H_3C-CH_2CH_2`

Answer 1

Propane combustion; `"option 4"`

Explanation:

`underbrace(C_3H_8(g) + 5O_2(g))_"6 moles" rarr underbrace(3CO_2(g) +4 H_2O(g))_"7 moles"`

Because `Vpropn" (T and P constant)"`, the VOLUMES represent the stoichiometric equivalents of hydrocarbon and oxidant.

You should write out all the combustion reactions with each fuel to satisfy yourself that this is the case:

i.e. `C_2H_4(g) +3O_2(g) rarr 2CO_2(g) +2H_2O(g)`, which stoichiometry disagrees with the experimental result.

You can do the rest.