What is the the heat of reaction, delta, in kJ/mol?
a) -26kJ/mol
b) -25kJ/mol
c) -10kJ/mol
d)-35kJ/mol

Answer:
b) -25 kJ/mol.
Explanation:
Hello there!
In this case, since the general definition of the enthalpy of reaction involves the subtraction of the energy of the products and the energy of the reactants:
[tex]\Delta H=H_{prod}-H_{react}[/tex]
Thus, since the graph shows that the energy of the products is 20 kJ/mol and that of reactants 45 kJ/mol, we will obtain:
[tex]\Delta H=20kJ/mol-45kJ/mol\\\\\Delta H=-25kJ/mol[/tex]
Which means it is exothermic.
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