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Stuck on Energy Density !!!

hiya, im really stuck on this chemistry question on energy density and i was just wondering if anyone has a clue how to do it!

Butan-2-ol could be used as a fuel. The standard enthalpy of Combustion of butan-2-ol is -2650KJ mol-1, its boiling temp 102c and its density 0.8gcm-3 Calculate energy density in KJ cm-3?

please please help!

Reply 1

initiation

work out how many grams are in a mol of butan-2-ol

Reply 2

meeraspatel

how do u work that out though coz wudnt the grams end up being the same as the Mr because moles = mass/mr n mass= moles x Mr
:s-smilie:

no idea bro sorry

meeraspatel

how do u work that out though coz wudnt the grams end up being the same as the Mr because moles = mass/mr n mass= moles x Mr
:s-smilie:

Look at the units kJ/cm³

1. Calculate the mass of 1 cm³ - to do this you need the density of each substance. Butan-2-ol = 0.8 g/cm³, hence 1 cm³ has a mass of 0.8g

2. Now calculate the moles in 1 cm³.

Relative mass of butan-2-ol = 74. Hence 0.8g = 0.8/74 moles = 0.0108

3. Now multiply by energy per mole

Energy per 0.0108 moles = 0.0108 x (-)2650 = -28.65 kJ cm^-3