Final answer:
To find the number of grams of carbon dioxide formed when 5.4 liters of hexane is burned in air at STP, we need to use the balanced equation for the combustion of hexane.
Step-by-step explanation:
The balanced equation is: 2 C6H14 + 19 O2 → 12 CO2 + 14 H2O. From the equation, we can see that for every 2 moles of hexane burned, 12 moles of carbon dioxide are formed. To convert liters of hexane to moles, we can use the ideal gas law: PV = nRT, where P is the pressure.
V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. At STP, the pressure is 1 atm and the temperature is 273 K. Using the ideal gas law, we can calculate the number of moles of hexane: n = PV / RT = (1 atm) * (5.4 L) / (0.0821 L * atm/mol * K * 273 K) = 0.235 mol.
So, the number of moles of carbon dioxide formed is 12 * 0.235 = 2.82 mol. The molar mass of carbon dioxide is 44.01 g/mol, so the mass of carbon dioxide formed is 2.82 mol * 44.01 g/mol = 124.63 g. Rounded to two decimal places, the answer is 124.63 grams.