Meaning of endothermic reactions with examples
Answer Text: Endothermic and exothermic reactions:(a). Endothermic reactions- Is a reaction accompanied by a fall in temperature and energy is absorbed from the surroundings.- The enthalpy change is normally positive since heat of products (H Products) is higher than heat of reactants (H reactants).- Thus #H_2-H_1# is a positive value; since H1 is less than #H_2#.Graphically this can be denoted as follows;-Examples:(i). When #NH_4NO_3# dissolves in water, the temperature of the solution drops.Procedure- A spatula end-full of ammonium nitrate is dropped into a test tube of water.- The bottom of the test tube is felt with the hand.Observations:- The hand feels cold.Reason:- Energy is absorbed by the products, cooling the test tube.Thus #H_1# is less than #H_2# giving a positive Δ #H_1# showing an endothermic reaction.(ii) #N_2(g) + O_2 (g) to 2NO(g); DeltaH=+91KJMol^-1#
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