Question

Given the equation: 2C8 H18 + 25 O2 --> 16 CO2 + 18 H2O, what is the volume of 02 with 49.5 g of H20?

Answer 1

`"91.7 L O"_2"` will be produced.

Explanation:

1. Divide the mass of water by its molar mass to get moles of water.
2. Multiply the moles of water times the mole ratio between oxygen and water from the balanced equation to get moles oxygen.

3. Multiply the moles oxygen times its molar mass to get mass of oxygen.

4. Divide the mass in grams of oxygen by its density in `"g/cm"^3"` to get its volume. Convert to liters.

`49.5cancel("g H"_2"O")xx(1cancel"mol H"_2"O")/(18.015cancel("g H"_2O))xx(25cancel"mol O"_2)/(18cancel"mol H"_2"O")xx(31.998"g O"_2)/(1cancel"mol O"_2)="122.1 g O"_2"`

The density of `"O"_2"` at room temperature is `"1.331 kg/m"^3=0.001331 "g/cm"^3"`.
http://www.engineeringtoolbox.com/gas-density-d_158.html

`122.1"g O"_2xx(1"cm"^3 "O"_2)/(0.001331"g O"_2)="91700 cm"^3 "O"_2"` (rounded to three significant figures)

Convert volume to liters.

`91700cancel"cm"^3xx(1cancel"mL")/(1cancel"cm"^3)xx(1"L")/(1000cancel"mL")="91.7 L O"_2"` (rounded to three significant figures)