Need help with MOLES calculation (1 Viewer)

[kittyful]

7. Three fuels commonly used in vehicles are petrol, LPG and ethanol. Some facts about them are given in the table.



(b) Calculate the mass of 1L of each fuel.
(c) Calculate the number of moles in 1L of each fuel.
(d) Calculate the heat produced by the combustion of 1L of each of these fuels.
(e) Fuel is sold by the volume. State two factors you need to consider in using each of these as fuels.

 

[ohexploitable]

(b) 1 mL of petrol will have a mass of 0.70g, 1L will have a mass of 0.7 x 1000 = 700g. Likewise, 1L of LPG will have a mass of 490g and 1L of ethanol will be 785g.

(c) Petrol (octane) is C₈H₁₈, its molar mass is 114.224 g/mol. 1L of petrol will have a mass of 700g, this mass will contain 700 / 114.224 = 6.128 moles. Likewise, 1L of LPG will contain 11.123 moles and 1L of ethanol will contain 17.421 moles.

(d) 1 mole of petrol will liberate 5460 kJ of heat, 6.128 moles (1L) will liberate 5460 x 6.128 = 33458.88 kJ of heat. Likewise, 1L of LPG will liberate 24693.06 kJ and 1L of ethanol will liberate 23814.507 kJ.

 

[Pseudo_Penguin]

(e) You have to take into account that the fuels have different densities, hence they will have a different mole to liter ratio eg/ 1L of ethanol will contain more fuel then 1L of petrol. You must also consider that 1 mole of a certain fuel will produce a different amount of energy compared to other types of fuels eg/ 1 mole of petrol will produce more energy then 1 mole of ethanol.