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glycogen
Dec3-04, 09:11 PM
Given: Cl2 = 58 kcal/mole ------> 2cl

1. 58 kcal/mole is the bond dissociation energy T F

2. 58 kcal/mole is an entropy term T F

3. this reactin is endothermic T F

I dont understand get it! Any help woud be appreciated.

Astronuc
Dec3-04, 09:50 PM
Did you mean to write Cl_2+58 kcal/mole \rightarrow 2 Cl?

If so, then think about what it means. What is happening when Cl_2 \rightarrow 2 Cl?

What are you doing with the energy?

Can it be the 'entropy' term?

so-crates
Dec3-04, 10:46 PM
Thats one notation. Most textbooks nowadays would say

Cl_2 \longrightarrow 2 Cl \ \ \ \ \Delta H^0 = +58 \ \ kcal/mol

to avoid confusion about the "energy" change in the system. (At constant pressure, enthalpy = heat added or lost)

A positive enthalphy change corresponds with heat being absorbed by the system. A negative enthalpy change corresponds to heat being released by the system.

glycogen
Dec4-04, 04:42 PM
Thanks for the explanations :). The formula makes sense now!