# AS Salters Chemical Storylines developing fuels assignment 14 and 15 help

Hi, I'm working in the AS Salters Chemical Storylines book, I was wondering if anyone can help me by giving me the method and answers to the developing fuels assignment 14 and 15 to check my answers and method...I'm really confused. Thank you!

Posted Wed 2nd January, 2013 @ 16:50 by K.N

whats the question?

Answered Wed 2nd January, 2013 @ 19:43 by Sakshat

1) calculate the amount of energy released by burning 45 litres of petrol, use the following info to help - assume that petrol is octane (C8H18), the standard enthalpy change of combustion is -5500KJ/mol, the density of octane is 0.70 g/cm3 and 1 litre is 1000cm3

2) calculate the mass and volume of hydrogen needed to provide the same amount of energy as 45 litres of octane - the standard enthalpy change of combustion of H2 is -286 KJ/mol and 1 mole of gas at 20°c and atmospheric pressure has a volume of about 24 litres.

3) H2 engines are 20% more efficient than petrol on the motorway and 50% more efficient than petrol in cities:
What mass and volume of H2 are needed to give the same mileage as 45 litres of petrol in
i) motorway
ii) city?
Thank you for any help!

Answered Wed 2nd January, 2013 @ 20:00 by K.N