When propane, C_3H_8, is burned, carbon dioxide and water vapor are produced according to the following reaction: C_3H_8 + 5O_2 -> 3CO_2 + 4H_2O. How much propane is burned if 160.0 g of O2 are used and 132 g of CO2 and 72.0 g of H2O are produced?

1 Answer
Dec 19, 2016

C_3H_8+5O_2 rarr 3CO_2 + 4H_2O

Precisely one mole, 44*g of pentane, were combusted.

Explanation:

"Moles of carbon dioxide:" (132*g)/(44.0*g*mol^-1)=3*mol

"Moles of water:" (72*g)/(18.01*g*mol^-1)=4*mol

"Moles of oxygen:" (160*g)/(32.0*g*mol^-1)=5*mol

Because there were 3 mol carbon dioxide produced, and stoichiometric water, one mole precisely of propane was combusted.

If pentane were burned in excess dioxygen, and 220*g carbon dioxide were produced, what was the starting mass of pentane?

C_5H_12 + 8O_2 rarr 5CO_2 + 6H_2O