What is the formula to calculate energy released?

foofighter15

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11 years ago

What is the formula to calculate energy released?

ok so i'm doing a lab now and i only have a few questions left but i'm confused.
It says i have to calculate the energy relaesed
what would the formula be for this?
Is it bascially just asking what the heat is? Is heat the energy released?
thank you, i thought that was what it was, i think i know what to do know, and sry for not giving all the info, but you've helped. Now i can finally finish the lab and hand it in tomorrow(its over a week late) Frowning Face

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Gaga19

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11 years ago

ok..it depends on what u are given. It would have been good if u had stated that in ur question. But when dealing with heat the equation thats used is:

Q = mc (delta T).....where M is the mass of reactants, C is the specific heat capacity and (dela T) is the change in temperature that occured...
MUltiply all these and u get ur answer!

PS: convert degrees celcius to Kelvin by added 273 to the temperatures

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desimaenugent

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11 years ago

Until a ChE comes along and gives you a better one - -
There can be several heats involved (excepting thermal nuclear). There are the latent heats of fusion and evaporation, and the common three heat transfers due to temperature differences.

But then there are the chemical heats of formation or of reactions. This involves these endo or exothermal chemical reactions. The heating value of a oxidized material ( a burning fuel) might be included here or it might be a separate category. (There is also the heat of adsorption of a desiccant.)

Most of these heats of formation can be found in the tables of Perry's (Chemical Engineering) Handbook. I don't have one.
Here is the only example I have. The heats of formation are specific to the compound. The heat of the whole reaction is found be adding and subtracting the heats of formation when plugged into the balanced equation. For instance - -

HCl +NaOH = NaCl + H2O
(-22)+ (-102)= (-98) + ( -68.3)
124= 166
Q = + 42 kCal/Mol
For a Mol of HCL (36.5 MW)
42 (1800)/36.5 = 2100 BTU/ pound of HCl reacted.
(1800 is a conversion factor to get to the US system which I use.)

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