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 H2-H1 is a positive value; since H1 is less than H2.Graphically this can be denoted as follows;-Examples:(i). When NH4NO3 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 H1 is less than H2 giving a positive Δ H1 showing an endothermic reaction.(ii) N2(g)+O2(g)→2NO(g);ΔH=+91KJMol-1