Question

In order to determine whether a chemical reaction is exothermic or endothermic, which of the following must be determined?

A.How energy flows
B.The number of products formed
C.The number of reactants used
D.How atoms are rearranged

Answer 1

To determine whether a chemical reaction is endothermic or exothermic one would have to determine how energy flows. In an endothermic reaction, energy flows from the environment into the system where in an exothermic reaction, energy is released from the system into the environment.

Answer 2

Answer: A. How energy flows

Explanation:-

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and
`\Delta H` for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and
`\Delta H` for the reaction comes out to be positive.

Thus in order to determine whether a chemical reaction is exothermic or endothermic , heat energy flow must be determined.