C3H8 + 5O2 → 3CO2 + 4H2O

What is the mass of O2 needed to produce 31.0 moles of H2O?
(2step)

m= 1240 g O2

Explanation: We will do stoichiometry for this problem to solve for the mass of O2 in grams.

First step is to convert the moles of H2O to moles of O2 using their mole ratio.

31.0 moles H2O x 5 moles O2 / 4 moles H2O

= 38.75 moles O2

Next is to convert the moles of O2 to mass using the molar mass of O2.

38.75 moles O2 x 32 g O2 / 1 mole O2 = 1,240 g O2

i believe that it is a exoplanet

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.

two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.