3. use the following ratio and proportion formula to determine the mass of butane needed to occupy a volume of 22.4 l at stp.

grams of butane you used “x” grams of butane
ml of butane corrected to stp = 22,400 ml

The molecular formula of butane is C₄H₁₀

Thus the molar mass of butane = 4 X 12 + 10 X 1 = 58 g/mol

According to Avagadro's law: the volume of an ideal gas is directly proportional to the moles of the gas molecules

Or

at STP (standard Temperature and pressure, 298K and 1atm)

The volume occupied by one mole of a gas is 22.4 L

thus the moles of butane occupying 22.4L of volume =1 mol

the mass of each mole of butane = 58g

Thus the mass of butane needed to occupy a volume of 22.4L at STP = 58g