Question

Identify the endothermic and exothermic reaction.

• A. $HCl+NaOH\to NaCl+H_{2}O+$heat
• B. $2KCl{O}_3\left(s\right)\stackrel{\Delta }{\to }2KCl\left(s\right)+3O_2\uparrow$
• C. $CaO+H_{2}O\to Ca(OH{)}_2+$heat
• D. $CaC{O}_3\left(s\right)\stackrel{\Delta }{\to }CaO\left(s\right)+C{O}_2\uparrow$

Answer 1

Answer: (A), (C)

The correct options are
A $HCl+NaOH\to NaCl+H_{2}O+$heat
C $CaO+H_{2}O\to Ca(OH{)}_2+$heat

Exothermic Reaction: In these reactions, energy is transferred from the reaction system into the surroundings. The average kinetic energy of the surroundings increases causing the reaction mixture to increase in temperature and get warmer. Means heat is released. Therefore reactions A and C are Exothermic reactions.

Endothermic Reactions: In these reactions, energy is absorbed from the surroundings. The average kinetic energy of the surrounding decreases causing the reaction mixture to get colder. Therefore energy is absorbed, means reaction B) and D)