Hello, Seema,
The answer depends somewhat on what you define as "powerful explosion." Do you want the most heat released? Or do you want the largest volume of gas (a bigger bang and more destructive for certain objects)?
The heat of combustion for the two candidates are:
Ethanol: -1,370 kJ/mol
Ethane: -1,559.5 kJ/mol
Adjusting for the masses of each, we convert the masses into moles:
Ethanol: 1.5g/(46 g/mole) = 0.0326 moles ethanol
Ethane: 1 g /(30 g/mole) = 0.0333 moles ethane
Thus each combustion reaction will produce:
Ethanol: (-1,370 kJ/mol)*(0.0326 mol) = -44.6 kJ for ethanol
Ethane: (-1,559.5 kJ/mol)*(0.0333 mol) = -51.9 kJ for ethane
The negative sign indicates that heat evolves from these reactions. We can see that the sample of ethane, although smaller, provides more heat energy that the sample of ethanol.
A key consideration is the state of the reactants. While ethane is likely a gas (under normal conditions), ethanol is likely a liquid. The liquid state will severely impede the speed of the reaction. So not only will ethanol release slightly less energy, it will also be spread over a greater length of time.
Ethanol will provide a glow. Ethane will clear out the audience with a loud, and dangerous, bang. (Use goggles and ear plugs, and let your labmate initiate the reaction).
Bob
