while calculating the energy do we use reactant minus product or product - reactant and here it is done as product minus reactant but usually it is reactant minus product so what is the usual case and how do I answer any question like this in exam
Solution
It depends on whether energy is releasing or absorbing after reaction.
The difference between the energy of the reactants and the energy of the products is called the enthalpy change (∆H) of the reaction. For an exothermic reaction, the products are at a lower energy than the reactants. In an endothermic reaction, the products are at a higher energy than the reactants.
So
It depends whether energy is absorbing or releasing.
Nuclear fusion requires high temperature for initiation so nuclear-fusion chain initiation is endothermic so here we considered product - reactant for binding energy and we get a positove value.
But generally we follow reactant - product and then you will get negative value of energy which will show that this is endothermic reaction.
It depends on whether energy is releasing or absorbing after reaction.
The difference between the energy of the reactants and the energy of the products is called the enthalpy change (∆H) of the reaction. For an exothermic reaction, the products are at a lower energy than the reactants. In an endothermic reaction, the products are at a higher energy than the reactants.
So
It depends whether energy is absorbing or releasing.
Nuclear fusion requires high temperature for initiation so nuclear-fusion chain initiation is endothermic so here we considered product - reactant for binding energy and we get a positove value.
But generally we follow reactant - product and then you will get negative value of energy which will show that this is endothermic reaction.