Anonymous asked in Science & MathematicsChemistry · 2 months ago

please help i want to drop chemistry ?

Explain how you would find the pressure of the gases in a 1 L container produced by the combustion of 255 g of octane at 22oC. (4 marks)?

1 Answer

  • 2 months ago
    Favorite Answer

    2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O

    Molar mass of C8H18 is 114.23 g/mol.  So the number of moles of octane was 2.2323.  You will end up with 8 times that many moles of CO2, and 9 times that many moles of H2O.  However, if we are to suppose that the gases are (now) at 22C, the water is liquid and only the CO2 is gaseous.  There are 362 g of water, occupying about 362 mL.  The 17.86 moles of CO2 are confined to 638 mL at 22C, so

    p = nRT/V = (17.86 mol)(0.08206 L*atm/molK)(295.15 K) /

    (0.638 L)

    = 678 atm.  Hmm, well now the water must be somewhat compressible, and the saturation pressure of CO2 at 22C is only 60 atmospheres, so the CO2 won't be gaseous either.

    My answer is, all of the products are in a liquid state under these conditions, so there is no gas and no gas pressure.

Still have questions? Get your answers by asking now.