What volume of oxygen gas at 20.9 c and 750 torr is needed to burn 3.00 liters of propane, C3H8 at the same temprrature and pressure?

Question

I know i use V1/n1=V2/n2, but how do i get n?

Answer 1

write the reaction first.

C3H8 + 5O2 >> 3CO2 + 4H2O

so you need five times the volume of O2, looks like 15 liters.

Remember, in gases, at the same temp, pressure, contain the same number of moles per volume. Gay-Lussac's law of combining volumes applies

Answer 2

Thank you this helped clearify things