Describle the ethanol!!???help (1 Viewer)

[callmetheking]

Descirble chemically the complete combustion of ethanol and provide, in an appropriate way, delta H comb.
thx~

 

[Dreamerish*~]

Complete combustion of ethanol releases only carbon dioxide and water, as shown in the following equation:

C₂H₅OH + 3O₂ →> 2CO₂ + 3H₂O

ΔH = -1360 kJ/mol

("The molar heat of combustion of a substance is the heat liberated when one mole of the substance undergoes complete combustion with oxygen at standard atmospheric pressure with the final products being carbon dioxide gas and liquid water." - Conquering Chemistry, fourth edition.)

 

[Riviet]

Wow 4th edition already, I have the 3rd one.

Just adding on, to obtain accurate values for the molar heat of combustion, a bomb calorimeter is used. It is made of a steel container where the fuel is combusted, surrounded by water where the heat is absorbed. The whole thing is surrounded by an insulated jacket.

An accurate figure for heat of combustion can not be achieved in the school laboratory using a rudimentary calorimeter because there is heat loss to the environment from the flame and also because complete combustion cannot be achieved in air that only contains 20% oxygen.

 

[pLuvia]

When finding the heat of combustion of ethanol, you should have realised that you would have lost a lot of energy when conducting the heat of combustion experiment. But your trend should be similar to the actual results.

 

[Mountain.Dew]

heres my 2 cents...

for ur result to be more accurate, the container (containing the water) should be suspended directly under the hottest part of the flame (is it the middle, or near the top?), AND the container must be a good heat conductor, like metal. i used a copper container for my experiment.

ALSO it is best to repeat ur experiment several times for more consistent results.

 

[mitsui]

Descirble chemically the complete combustion of ethanol and provide, in an appropriate way, delta H comb.
thx~

wat is that "delta H comb"?? o.o

 

[insert-username]

wat is that "delta H comb"?? o.o

The molar heat of combustion - ΔH = mCΔT, where ΔH is heat of combustion, m is the mass of water (or the substance heated), C is the specific heat capacity of water (or the substance heated) and ΔT is the change in temperature.


I_F