2 C8H18(l) + 25 O2(g) ----> 16 CO2(g) + 18 H2O(g) If 4.00 moles of gasoline are burned, what volume of oxygen is needed if the pressure is 0.953 atm, and the temperature is 35.0°C?

1 Answer
Jan 31, 2015

Start by looking at the mole ratio between C8H18 and O2; notice that you need 25 moles of O2 for every 2 moles of C8H18. SInce you start with 4 moles of C8H18, the number of O2 moles you'll need is

4.00 moles C8H1825 moles O22 moles C8H18=50.0 moles O2

Now all you need to do is use the ideal gas law equation, PV=nRT, to solve for the volume of O2 needed (don't forget to transform degrees Celsius to Kelvin)

PV=nRTV=nRTP

VO2=50.0 moles0.082LatmmolK(273.15 + 35)K0.953 atm

VO2=1325.7 L, or VO2=1330 L - rounded to three sig figs.