find the mass of C3H8 required to generate 2.5x10^8 KJ of energy when combusted with O2 gas to produce CO2 gas and water vapor

To find the mass of C3H8 required to generate 2.5x10^8 kJ of energy when combusted with O2 gas, we need to use the concept of stoichiometry and the balanced chemical equation for the combustion reaction. The balanced equation for the combustion of C3H8 (propane) is:

C3H8 + 5O2 -> 3CO2 + 4H2O

From this equation, we can see that one mole of C3H8 reacts with 5 moles of O2 to produce 3 moles of CO2 and 4 moles of H2O.

Now, let's calculate the molar enthalpy change for the combustion of C3H8. The molar enthalpy change is given as -2220 kJ/mol, which means that for every mole of C3H8 burned, 2220 kJ of energy is released.

Next, we will calculate the number of moles of C3H8 required to generate 2.5x10^8 kJ of energy:

Number of moles = Energy / Molar enthalpy change

Number of moles = (2.5x10^8 kJ) / (2220 kJ/mol)

Number of moles ≈ 112613.06 mol

Finally, to find the mass of C3H8 required, we need to multiply the number of moles by its molar mass. The molar mass of C3H8 is:

3(12.01 g/mol) + 8(1.01 g/mol) = 44.11 g/mol

Mass of C3H8 = Number of moles × Molar mass

Mass of C3H8 = (112613.06 mol) × (44.11 g/mol)

Mass of C3H8 ≈ 4.96x10^6 g or 4960 kg

Therefore, approximately 4960 kg of C3H8 is required to generate 2.5x10^8 kJ of energy when combusted with O2 gas.