Jennifer H. answered • 11/04/20

Caring, Experienced Chemistry Teacher Catalyzing Student Success

Here is the plan: You have 82.9 L of oxygen at STP. Since the system is at STP you can use the molar volume of any gas at STP of 22.4L/mole to convert to moles of O_{2}. Next, you can use mole ratio from the coefficients in the balanced equation to convert from moles of O2 to moles of pentane and finally, multiply by molar mass of pentane (use periodic table to calculate) to get grams of pentane. Round answer to correct number of significant digits which would be 3 digits since the measurement given in the problem has 3 digits.

Applying the plan:

82.9 L O2 x (1 mole O_{2}/22.4 L O_{2}) x (1 mole C_{5}H_{12}/8 moles O_{2}) x (72.15 g C_{5}H_{12}/1 mole C_{5}H_{12})= 33.4 g C_{5}H_{12}