Question

In a chemical reaction, the reactants are substances that undergo the reaction, and the products are substances that are formed during the reaction. The table below shows the reactants and products of several different chemical reactions.

Reactants Products Type of Reaction
4K + O2] [2K2O + heat] Exothermic
2H2O + heat] [2H2 + O2] Endothermic
2CO + O2] [2CO2 + heat] Exothermic
CaCO3 + hea] [CaO + CO2] Endothermic


Based on the information given in the above table, the best definition of an endothermic reaction would be?
A. a reaction that releases heat.
B. a reaction that absorbs heat.
C. a reaction that has one product.
D. a reaction that does not require heat.

Answer 1

(B). a reaction that absorbs heat

Step-by-step explanation:

Like,

In 1st 4 Pottasium with 1 Oxygen molecule gives 2 Pottasium oxide along with heat released .

In the 3rd 2 carbon monoxide compounds react with 1 Oxygen molecule to give 2 Carbon dioxide compound molecule along with heat release .

Thus as both of the reactions are giving out heat in their products they are called exothermic reaction.

While,

In the 2nd reaction 2 water molecules under heat decompose giving out 2 hydrogen and 1 Oxygen molecule .

In the 4th reaction Calcium carbonate compound under heat gives out calcium oxide and carbon dioxide molecule.

Thus as both reaction are absorbing heat and it is given that they are called as endothermic reaction we can infer that the reactions in which heat absorption takes place are referred to as endothermic reaction.