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| Illustration of Stove Fire Source of pictures: www.istockphoto.com |
Thermodynamics Law, as we know, consists of two values. These values are called enthalpy. Enthalpy here is the same with qp (heat). Someday, when I look at a book or in internet, these times I found that several parts of value of enthalpy in the thermodynamics law are wrong. We usually see in literature which contain chemistry lesson the enthalpy of exothermic reaction is minus and endothermic reaction is plus. It is said that exothermic reaction is used to describe joining of matters reactions. Whereas endothermic reaction is used to describe separation of matters reactions.
The examples of them are campfire. When twig of tree is combusted, it will release heat. We can say that its release heat and yield heat at the same time, makes it has positive enthalpy. This thing happens cause the speed of releasing heat and yielding heat is not equal. The calculation of enthalpy (during 32 minutes) according to scientists is (suppose the burned thing is one-kilogram-sized plastic):
1. Calculate the releasing enthalpy
(i) Yellow fire:
q = ρ a6/ λ t2
= (4.97388489447020344381522963 x 1015 x (2,791.775011174)6) /
(28.712543216521435 x 94.165824191576446432888456086 x
(1,919.8532648569332355099046221)2)
= 2.3630878249845387670439256 x 1026 J
(ii) Orange fire:
q = ρ a6/ λ t2
= (
2. Calculate the yielding enthalpy
(i) q = m x ρ x T27/T17
= ((15.214314)2/43.31485) x ((1521)7/(28.214316)7)
= 70,710.8000532131182661874053 J
(ii) qtot = q1 + q2 + q3 + q4
=
Where the a alphabet means amplitude.
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