Step-by-step explanation:
There are two type of reaction possible , i.e. , exothermic and endothermic reaction ,
Exothermic reaction -
The type of reaction in which energy in the form of heat or light is released , is known as exothermic reaction ,
The reaction mixture usually get heated after the reaction .( temperature increases ) .
The sign of ΔH of an exothermic reaction is negative .
Similarly ,
Endothermic reaction -
The type of reaction in which energy is absorbed in the form of heat is known as endothermic reaction .
The reaction mixture usually get cooled after the reaction .( temperature decreases ) .
The sign of ΔH of an Endothermic reaction is positive .
a. dry ice evaporating ,
Endothermic reaction , ΔH = positive .
b. a sparkler burning ,
Exothermic reaction ΔH = negative .
c. the reaction that occurs in a chemical cold pack often used to ice athletic injuries
Endothermic reaction , ΔH = positive .