Question

When Cao is added to water taker in a beaker, rise in temperature is observed . However when Ba(OH)2is mixed with NH4Cl , a fall in temperature is observed . Why? Write the chemical equation as well.

Answer 1

Case I :-

When CaO is added to water taker in a beaker, rise in temperature is observed because it is an Exothermic reaction. (In Exothermic reaction heat is released during the reaction.)

→CaO + H₂O ⇒ Ca(OH)₂

Case II :-

When Ba(OH)₂ is mixed with NH₄Cl , a fall in temperature is observed because it is an Endothermic Reaction. (In Endothermic Reaction heat is absorbed during the reaction.)

→Ba(OH)₂ + NH₄Cl ⇒ BaCl₂ + 2H₂O + 2NH₃