Question

What mass of oxygen is needed to react with 4.5g of ethane `C_2H_8`?

Answer 1

We need approx. `17*g` of dioxygen.

Explanation:

A balanced chemical equation is required:

`H_3C-CH_3 + 7/2O_2(g) rarr 2CO_2(g) +3H_2O(g)`

And thus each equiv ethane requires `7/2` equiv of dioxygen.

`"Moles of ethane"` `=` `(4.5*g)/(30.07*g*mol^-1)` `=` `0.15*mol`

And thus we need:

`7/2xx0.15*molxx32.00*g*mol^-1" dioxygen gas"` `=` `??g`