Question

What mass of benzene is required for a combustion reaction that yields a mass of `42*g` with respect to carbon dioxide?

Answer 1

Approx. `13*g` benzene were required.

Explanation:

Given the stoichiometric rxn:

`C_6H_6(l) + 15/2O_2(g) rarr 6CO_2(g) + 3H_2O(l)`

As a product we have `(42.0*g)/(44.01*g*mol^-1)` `~=` `1*mol" carbon dioxide"` gas.

And thus approx. `1/6*mol` benzene were required for the combustion, `=` `1/6molxx78.0*g*mol^-1` `=` `??*g`.

You can of course make a better estimate than I did.