Question

How many moles are necessary to react completely with four moles of propane in the reaction `C_3H_8 + 5O_2 -> 3CO_2 + 4H_2O`?

Answer 1

`20mol " of "O_2`

Explanation:

I assume that the question is about how many moles of oxygen that will react completely with four moles of propane.

From the balanced equation:

`C_3H_8+5O_2->3CO_2+4H_2O`

Every 1 mole of `C_3H_8` reacts with 5 moles of `O_2` , therefore,

`?molO_2=4cancel(molC_3H_8)xx(5molO_2)/(1cancel(molC_3H_8))=20 molO_2`